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Acquisitions (Details) $ in Thousands, SFr in Millions				12 Months Ended
Acquisitions (Details) $ in Thousands, SFr in Millions	Jan. 19, 2023 USD ($)	Jan. 19, 2023 CHF (SFr)	Jul. 21, 2022 USD ($)	Dec. 31, 2023 USD ($)	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)	Sep. 30, 2022 CHF (SFr)
Business Acquisition [Line Items]
Equity securities without readily determinable fair value, amount \| SFr							SFr 8.0
Acquired in-process research and development expenses \| $				$ 78,750	$ 31,039	$ 0
AMF Medical Acquisition
Business Acquisition [Line Items]
Payments of cash \| SFr		SFr 62.4
Additional earnout payment \| SFr		SFr 129.6
Milestone period	2 years	2 years
Acquired in-process research and development expenses \| $	$ 78,800
AMF Medical Acquisition \| Development Milestones
Business Acquisition [Line Items]
Additional earnout payment \| SFr		SFr 38.4
AMF Medical Acquisition \| Regulatory Clearance Milestone
Business Acquisition [Line Items]
Additional earnout payment \| SFr		SFr 91.2
Capillary Biomedical
Business Acquisition [Line Items]
Acquired in-process research and development expenses \| $			$ 31,000
Asset acquisition, purchase price \| $			24,700
Long term debt assumed \| $			$ 4,700	$ 4,700	$ 4,700

Label	Element	Value
Accounting Standards Update [Extensible Enumeration]	us-gaap_AccountingStandardsUpdateExtensibleList	Accounting Standards Update 2020-06 [Member]

- Definition

Indicates amendment to accounting standards.

+ References

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+ Details

Leases - Lease Payments (Details) - USD ($) $ in Thousands	12 Months Ended
Leases - Lease Payments (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Leases [Abstract]
Operating lease payments	$ 13,864	$ 11,960	$ 9,462
Operating lease termination payments	0	4,769	0
Total cash payments	$ 13,864	$ 16,729	$ 9,462

Composition of Certain Financial Statement Items

12 Months Ended

Dec. 31, 2023

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Composition of Certain Financial Statement Items

Accounts Receivable

Accounts receivable, net consisted of the following at December 31, 2023 and 2022 (in thousands):


	December 31,		December 31,
	2023		2022

Accounts receivable	$	110,453	$	119,044
Less: allowance for credit losses	(4,898)		(4,327)
Accounts receivable, net	$	105,555	$	114,717

Allowance for Credit Losses

The following table provides a reconciliation of the changes in the allowance for estimated accounts receivable credit losses for the years ended December 31, 2023, 2022 and 2021 (in thousands):


	Year Ended December 31,
		2023		2022		2021
Balance at beginning of the period		$	4,327	$	4,249	$	3,857
Provision for expected credit losses		5,540		4,782		2,333
Write-offs and adjustments, net of recoveries		(4,969)		(4,704)		(1,941)
Balance at end of the period		$	4,898	$	4,327	$	4,249

Inventories

Inventories consisted of the following at December 31, 2023 and 2022 (in thousands):


	December 31,
	2023		2022

Raw materials	$	42,783	$	39,207
Work-in-process	44,026		18,571
Finished goods	71,128		53,339
Total inventories	$	157,937	$	111,117

Property and Equipment

Property and equipment, net consisted of the following at December 31, 2023 and 2022 (in thousands):


	December 31,
	2023		2022
Leasehold improvements	$	37,565	$	35,828
Office furniture and equipment	11,842		13,772
Computer equipment and software	10,340		12,330
Manufacturing and scientific equipment	69,589		62,797
Total cost	129,336		124,727
Less: accumulated depreciation and amortization	(52,794)		(56,175)
Total property and equipment, net	$	76,542	$	68,552

Depreciation and amortization expense related to property and equipment was $13.8 million, $12.3 million, and $11.7 million for the years ended December 31, 2023, 2022 and 2021, respectively.

Intangible Assets Subject to Amortization

Intangible assets subject to amortization consist of technology-based intangibles related to the Company’s acquisition of Sugarmate, as well as patents purchased or licensed that are related to the Company’s commercialized products. Intangible assets at December 31, 2023 and 2022, which were included in other long-term assets on the consolidated balance sheets, were as follows (in thousands):


	December 31,
	2023		2022
Intangible assets, gross amount	$	12,502	$	12,502
Accumulated amortization	(9,726)		(7,875)
Intangible assets, net	$	2,776	$	4,627
Weighted average remaining amortization period (in months)	18		30

Amortization expense related to intangible assets subject to amortization amounted to $1.9 million, $2.0 million and $2.2 million for the years ended December 31, 2023, 2022 and 2021, respectively. The amortization expense is recorded in cost of sales and selling, general and administrative expense in the consolidated statement of operations. The estimated aggregate future amortization expense is $1.9 million for 2024, and the remaining $0.9 million in 2025, all of which will be recorded in selling, general and administrative expense in the consolidated statement of operations

Fair Value Measurements - Financial Assets and Liabilities Measured at Fair Value on Recurring Basis (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2023	Dec. 31, 2022
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt securities, available for sale	$ 409,044	$ 444,384
Maximum
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash equivalents maturity term	3 months	3 months
U.S. Treasury securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt securities, available for sale	$ 115,004	$ 211,161
Commercial paper
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt securities, available for sale	72,511	112,610
Corporate debt securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt securities, available for sale	39,375	18,114
Supranational bonds
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt securities, available for sale		2,491
Fair Value, Measurements, Recurring
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total assets	457,077	595,126
Fair Value, Measurements, Recurring \| Level 1
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total assets	163,037	361,903
Fair Value, Measurements, Recurring \| Level 2
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total assets	294,040	233,223
Fair Value, Measurements, Recurring \| Level 3
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total assets	0	0
Fair Value, Measurements, Recurring \| Cash equivalents
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash equivalents	48,033	150,742
Fair Value, Measurements, Recurring \| Cash equivalents \| Level 1
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash equivalents	48,033	150,742
Fair Value, Measurements, Recurring \| Cash equivalents \| Level 2
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash equivalents	0	0
Fair Value, Measurements, Recurring \| Cash equivalents \| Level 3
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash equivalents	0	0
Fair Value, Measurements, Recurring \| U.S. Government-sponsored enterprises
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt securities, available for sale	182,154	100,008
Fair Value, Measurements, Recurring \| U.S. Government-sponsored enterprises \| Level 1
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt securities, available for sale	0	0
Fair Value, Measurements, Recurring \| U.S. Government-sponsored enterprises \| Level 2
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt securities, available for sale	182,154	100,008
Fair Value, Measurements, Recurring \| U.S. Government-sponsored enterprises \| Level 3
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt securities, available for sale	0	0
Fair Value, Measurements, Recurring \| U.S. Treasury securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt securities, available for sale	115,004	211,161
Fair Value, Measurements, Recurring \| U.S. Treasury securities \| Level 1
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt securities, available for sale	115,004	211,161
Fair Value, Measurements, Recurring \| U.S. Treasury securities \| Level 2
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt securities, available for sale	0	0
Fair Value, Measurements, Recurring \| U.S. Treasury securities \| Level 3
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt securities, available for sale	0	0
Fair Value, Measurements, Recurring \| Commercial paper
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash equivalents	72,511	112,610
Fair Value, Measurements, Recurring \| Commercial paper \| Level 1
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash equivalents	0	0
Fair Value, Measurements, Recurring \| Commercial paper \| Level 2
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash equivalents	72,511	112,610
Fair Value, Measurements, Recurring \| Commercial paper \| Level 3
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash equivalents	0	0
Fair Value, Measurements, Recurring \| Corporate debt securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt securities, available for sale	39,375	18,114
Fair Value, Measurements, Recurring \| Corporate debt securities \| Level 1
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt securities, available for sale	0	0
Fair Value, Measurements, Recurring \| Corporate debt securities \| Level 2
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt securities, available for sale	39,375	18,114
Fair Value, Measurements, Recurring \| Corporate debt securities \| Level 3
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt securities, available for sale	$ 0	0
Fair Value, Measurements, Recurring \| Supranational bonds
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt securities, available for sale		2,491
Fair Value, Measurements, Recurring \| Supranational bonds \| Level 1
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt securities, available for sale		0
Fair Value, Measurements, Recurring \| Supranational bonds \| Level 2
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt securities, available for sale		2,491
Fair Value, Measurements, Recurring \| Supranational bonds \| Level 3
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt securities, available for sale		$ 0

Leases - Lease Cost, Lease Term Discount Rate, Operating Leases (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Leases [Abstract]
Operating lease cost	$ 15,971	$ 18,432	$ 8,627
Short-term lease cost	108	142	90
Loss on lease termination and right-of-use asset impairment charges	11,224	5,699	0
Total lease cost	$ 27,303	$ 24,273	$ 8,717
Weighted-average remaining lease term (in years)	10 years 2 months 12 days	10 years 9 months 18 days
Weighted-average discount rate used to determine operating lease liabilities	5.40%	5.30%

Income Taxes - Schedule of Unrecognized Tax Benefits (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Gross unrecognized tax benefits at the beginning of the year	$ 16,986	$ 13,589	$ 10,107
Increases related to current year positions	3,961	3,403	3,482
Increases (decreases) related to prior year positions	580		0
Increases (decreases) related to prior year positions		(6)
Gross unrecognized tax benefits at the end of the year	$ 21,527	$ 16,986	$ 13,589

Summary of Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2023

Accounting Policies [Abstract]

Schedule of Customers Accounted for 10% or More

The following table summarizes the percentages of total sales and accounts receivable, net for customers who accounted for 10% or more of the respective amounts for the periods presented:


	Total Sales						Accounts Receivable, net
	Year Ended December 31,						December 31,
	2023		2022		2021		2023		2022
Distributor B	12.2	%	11.6	%	11.9	%	10.0	%	12.8	%
Distributor C	*		*		*		10.5	%	*
Distributor D	*		*		*		10.6	%	10.4	%
Distributor E	10.8	%	14.4	%	14.0	%	11.5	%	16.2	%

* Amount related to the respective customer represented less than 10% for the period presented.

Schedule of Reconciliation of Change in Estimated Warranty Liabilities

The following table provides a reconciliation of the changes in product warranty liabilities for the years ended December 31, 2023, 2022 and 2021 (in thousands):


	Year Ended December 31,
		2023		2022		2021
Balance at beginning of the period		$	36,537	$	30,401	$	22,075
Provision for warranties issued during the period		35,690		32,699		27,604
Settlements made during the period		(32,617)		(25,447)		(18,768)
Decreases in warranty estimates		(2,437)		(1,116)		(510)
Balance at end of the period		$	37,173	$	36,537	$	30,401

As of December 31, 2023 and 2022, total product warranty reserves were included in the following consolidated balance sheet accounts (in thousands):


	December 31, 2023		December 31, 2022

Other current liabilities	$	18,135	$	17,280
Other long-term liabilities	19,038		19,257
Total warranty reserve	$	37,173	$	36,537

Schedule of Earnings (Loss) Per Share, Basic and Diluted

For the years ended December 31, 2023, 2022 and 2021, the numerator and denominator of the diluted net income (loss) per share computation were calculated as follows (in thousands):


	Year Ended December 31,
	2023		2022		2021
Net income (loss) - basic and diluted	$	(222,611)	$	(94,594)	$	15,566



Weighted average shares outstanding - basic	64,969		64,146		63,000
Dilutive common share equivalents:
Options to purchase common stock	—		—		1,129
Unvested restricted stock units	—		—		62
Warrants to purchase common stock	—		—		157
Awards to be granted under the ESPP	—		—		1

Weighted average shares outstanding - diluted	64,969		64,146		64,349

Schedule of Anti-Dilutive Securities

Potentially dilutive securities outstanding and not included in the calculation of diluted net loss per share (because inclusion would be anti-dilutive) are as follows (in thousands, in common stock equivalent shares):


	Year Ended December 31,
		2023	2022	2021
Options to purchase common stock		135	1,138	3,124
Unvested restricted stock units		2,089	1,118	—
Warrants to purchase common stock		194	194	1
Awards granted under the ESPP		14	8	—
Convertible senior notes (if-converted)		2,554	2,554	2,554
		4,986	5,012	5,679

Stockholders' Equity - Restricted Stock Units (RSUs) (Details) - Restricted Stock Units (RSUs) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Total RSUs
Unvested awards outstanding at beginning balance (in shares)	1,833,832	610,731	132,802
RSUs granted (in shares)	2,359,907	1,542,859	564,034
Vested (in shares)	(735,155)	(202,215)	(53,957)
Canceled/forfeited/expired (in shares)	(282,425)	(117,543)	(32,148)
Unvested awards outstanding at ending balance (in shares)	3,176,159	1,833,832	610,731
Weighted-Average Grant Date Fair Value
Unvested awards outstanding at beginning balance (in dollars per share)	$ 72.57	$ 95.08	$ 82.82
Weighted average grant date fair value (in dollars per share)	28.13	67.09	96.37
Vested (in dollars per share)	73.17	91.99	82.74
Canceled/forfeited/expired (in dollars per share)	59.17	84.20	87.21
Unvested awards outstanding at ending balance (in dollars per share)	$ 40.61	$ 72.57	$ 95.08
Aggregate intrinsic value outstanding balance	$ 93,951	$ 82,431	$ 91,927	$ 12,706
Awards expected to vest (in shares)	3,088,745
Awards expected to vest (in dollars per share)	$ 40.50
Awards expected to vest, aggregate intrinsic value	$ 91,365

Income Taxes - Schedule of Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Components of Deferred Tax Assets [Abstract]
Net operating loss (NOL) carryforwards	$ 54,802	$ 54,598
Research and development tax credits carryforwards	27,516	22,400
Capitalized research and development expenses	52,875	29,760
Accrued compensation	32,097	34,378
Lease liabilities	31,037	32,738
Other	20,778	20,927
Total deferred tax assets	219,105	194,801
Components of Deferred Tax Liabilities [Abstract]
Operating lease right-of-use assets	(20,869)	(26,505)
Fixed assets	(6,916)	(4,467)
Other	(656)	(1,103)
Total deferred tax liabilities	(28,441)	(32,075)
Less valuation allowance	(190,664)	(162,726)
Net deferred tax assets	$ 0	$ 0

Debt - Components of Convertible Note (Details) - Convertible senior notes - Convertible senior notes - USD ($)	Dec. 31, 2023	Dec. 31, 2022	May 31, 2020
Debt Instrument [Line Items]
Principal amount	$ 287,500,000	$ 287,500,000	$ 287,500,000
Unamortized debt issuance costs	(2,465,000)	(4,268,000)
Net carrying amount	$ 285,035,000	$ 283,232,000

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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+ Details

- Definition

Amount, after deduction of unamortized premium (discount) and debt issuance cost, of long-term debt. Excludes lease obligation.

+ References + Details

Audit Information	12 Months Ended
Audit Information	Dec. 31, 2023
Audit Information [Abstract]
Auditor Name	Ernst & Young LLP
Auditor Location	San Diego, California
Auditor Firm ID	42

Stockholders' Equity - Allocation of Stock-Based Compensation Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation expense	$ 88,077	$ 84,918	$ 60,752
Cost of sales
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation expense	6,212	7,685	6,434
Selling, general and administrative
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation expense	56,304	57,196	43,567
Research and development
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation expense	$ 25,561	$ 20,037	$ 10,751

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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+ Details

Short-Term Investments - Estimated Fair Value of Short-Term Investments (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Cash Cash Equivalents And Short Term Investments [Line Items]
Amortized Cost	$ 408,295	$ 447,241
Gross Unrealized Gain	1,025	30
Gross Unrealized Loss	(276)	(2,887)
Estimated Fair Value	409,044	444,384
U.S. Government-sponsored enterprises
Cash Cash Equivalents And Short Term Investments [Line Items]
Amortized Cost	181,851	100,602
Gross Unrealized Gain	518	21
Gross Unrealized Loss	(215)	(615)
Estimated Fair Value	182,154	100,008
U.S. Treasury securities
Cash Cash Equivalents And Short Term Investments [Line Items]
Amortized Cost	114,714	213,105
Gross Unrealized Gain	318	3
Gross Unrealized Loss	(28)	(1,947)
Estimated Fair Value	115,004	211,161
Commercial paper
Cash Cash Equivalents And Short Term Investments [Line Items]
Amortized Cost	72,505	112,812
Gross Unrealized Gain	33	6
Gross Unrealized Loss	(27)	(208)
Estimated Fair Value	72,511	112,610
Corporate debt securities
Cash Cash Equivalents And Short Term Investments [Line Items]
Amortized Cost	39,225	18,218
Gross Unrealized Gain	156	0
Gross Unrealized Loss	(6)	(104)
Estimated Fair Value	$ 39,375	18,114
Supranational bonds
Cash Cash Equivalents And Short Term Investments [Line Items]
Amortized Cost		2,504
Gross Unrealized Gain		0
Gross Unrealized Loss		(13)
Estimated Fair Value		$ 2,491

Stockholders' Equity -Shares of Common Stock Reserved for Future Issuance (Details) - shares	Dec. 31, 2023	May 31, 2023
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved for future issuance (in shares)	10,976,000	2,602,184
Shares reserved for issuance upon conversion of Convertible Senior Notes
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved for future issuance (in shares)	2,554,000
Shares underlying outstanding warrants
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved for future issuance (in shares)	194,000
Shares underlying outstanding stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved for future issuance (in shares)	3,896,000
Shares underlying unvested restricted stock units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved for future issuance (in shares)	3,176,000
Shares authorized for issuance pursuant to awards granted under the ESPP
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved for future issuance (in shares)	454,000
Shares authorized for future equity award grants
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved for future issuance (in shares)	702,000

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

+ Details

Summary of Significant Accounting Policies - Customers Accounted for 10% or More (Detail) - Customer Concentration Risk	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Total Sales \| Distributor B
Concentration Risk [Line Items]
Customers accounted for 10% or more	12.20%	11.60%	11.90%
Total Sales \| Distributor E
Concentration Risk [Line Items]
Customers accounted for 10% or more	10.80%	14.40%	14.00%
Accounts Receivable, net \| Distributor B
Concentration Risk [Line Items]
Customers accounted for 10% or more	10.00%	12.80%
Accounts Receivable, net \| Distributor C
Concentration Risk [Line Items]
Customers accounted for 10% or more	10.50%
Accounts Receivable, net \| Distributor D
Concentration Risk [Line Items]
Customers accounted for 10% or more	10.60%	10.40%
Accounts Receivable, net \| Distributor E
Concentration Risk [Line Items]
Customers accounted for 10% or more	11.50%	16.20%

Leases - Additional Information (Details)	1 Months Ended		3 Months Ended		12 Months Ended
Leases - Additional Information (Details)	May 30, 2025 USD ($)	Sep. 30, 2022 USD ($)	Jun. 30, 2023 USD ($) ft²	Dec. 31, 2022 USD ($)	Dec. 31, 2023 USD ($)	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)	Mar. 31, 2022 USD ($) extension	Sep. 30, 2021 ft²
Lessee, Lease, Description [Line Items]
Operating lease right-of-use assets				$ 110,626,000	$ 87,791,000	$ 110,626,000
Operating lease, liability					130,632,000
Operating lease, liability to be paid 2029 through 2035					90,004,000
Impairment of long-lived assets					0	$ 0	$ 0
Operating lease, impairment loss				1,900,000
Operating lease termination and impairment charges				12,400,000
Loss on disposition of assets				6,700,000
Loss on termination of lease				$ 3,800,000
Headquarters Lease
Lessee, Lease, Description [Line Items]
Area of office space leased \| ft²									181,949
Operating lease, number of options to extend \| extension								2
Annual percentage increase in monthly base rent		3.00%
Headquarters Lease Phase I
Lessee, Lease, Description [Line Items]
Area of office space leased \| ft²			77,458						143,850
Operating lease extension period								5 years
Monthly base rent		$ 906,000
Beginning period after initial lease term for which no rent is due				2 months		2 months
Ending period for which no rent is due				9 months		9 months
Operating lease right-of-use assets								$ 107,500,000
Operating lease, liability								$ 107,500,000
Headquarters Lease Phase II
Lessee, Lease, Description [Line Items]
Area of office space leased \| ft²									38,099
Operating lease, liability to be paid 2025 through 2028					2,200,000
Operating lease, liability to be paid 2029 through 2035					$ 23,200,000
Headquarters Lease Phase II \| Forecast
Lessee, Lease, Description [Line Items]
Increase in monthly base rent	$ 255,000
Beginning period after initial lease term for which no rent is due	2 months
Ending period for which no rent is due	5 months
Headquarters Lease, Additional Space
Lessee, Lease, Description [Line Items]
Area of office space leased \| ft²									16,154
Vista Sorrento Lease
Lessee, Lease, Description [Line Items]
Area of office space leased \| ft²			73,929
Vista Sorrento Lease \| Lease Agreements
Lessee, Lease, Description [Line Items]
Impairment of long-lived assets			$ 14,100,000
Operating lease, impairment loss			11,200,000
Write-off of fixed assets			$ 2,900,000
Minimum
Lessee, Lease, Description [Line Items]
Lease term					2 years
Maximum
Lessee, Lease, Description [Line Items]
Lease term					13 years

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Operating Activities
Net income (loss)	$ (222,611)	$ (94,594)	$ 15,566
Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities:
Depreciation and amortization expense	15,715	14,330	13,845
Amortization of debt issuance costs	2,204	1,896	1,727
Provision for expected credit losses	5,540	4,782	2,333
Operating lease termination and impairment charges	14,099	7,567	0
Amortization of premium on short-term investments	3,587	4,187	365
Stock-based compensation expense	88,076	84,918	60,752
Acquired in-process research and development expenses	78,750	31,039	0
Other	515	988	2,399
Changes in operating assets and liabilities:
Accounts receivable, net	4,277	(7,830)	(30,980)
Inventories	(46,053)	(42,452)	(4,954)
Prepaid and other current assets	(9,139)	(58)	(1,570)
Other long-term assets	(3,187)	(1,207)	1,313
Accounts payable	(4,864)	24,493	10,275
Accrued expenses	2,537	(461)	4,640
Employee-related liabilities	5,167	(12,869)	17,399
Deferred revenue	21,525	8,358	10,611
Operating leases and other current liabilities	4,302	25,445	6,217
Other long-term liabilities	7,750	1,932	1,421
Net cash provided by (used in) operating activities	(31,810)	50,464	111,359
Investing Activities
Purchases of short-term investments	(510,859)	(467,652)	(733,388)
Proceeds from maturities and redemptions of short-term investments	546,218	569,492	570,023
Purchases of property and equipment	(26,804)	(34,097)	(14,180)
Acquisitions, including in-process research and development, net of cash acquired	(69,496)	(25,720)	0
Purchases of intangible assets and strategic investments	(24,799)	(8,855)	(9,331)
Net cash used in investing activities	(85,740)	33,168	(186,876)
Financing Activities
Proceeds from issuance of common stock under Company stock plans, net	4,184	17,469	51,340
Proceeds from exercise of common stock warrants	0	83	592
Other financing activities	(71)	(675)	0
Net cash provided by financing activities	4,113	16,877	51,932
Effect of foreign exchange rate changes on cash	(212)	827	153
Net increase (decrease) in cash and cash equivalents	(113,649)	101,336	(23,432)
Cash and cash equivalents at beginning of period	172,517	71,181	94,613
Cash and cash equivalents at end of period	58,868	172,517	71,181
Supplemental disclosures of cash flow information
Interest paid	7,565	4,313	4,313
Income taxes paid	1,923	411	260
Supplemental schedule of non-cash investing and financing activities
Operating lease right-of-use assets obtained in exchange for operating lease obligations	0	114,003	15,191
Purchases of property and equipment included in accounts payable	2,946	4,237	1,034
Intangible costs in accounts payable	$ 0	$ 515	$ 1,029

Composition of Certain Financial Statement Items - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Depreciation and amortization expense related to property and equipment	$ 13.8	$ 12.3	$ 11.7
Amortization expense related to intangible assets	1.9	$ 2.0	$ 2.2
Estimated annual amortization for 2024	1.9
Estimated annual amortization for 2025	$ 0.9

Composition of Certain Financial Statement Items (Tables)

12 Months Ended

Dec. 31, 2023

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Schedule of Accounts Receivable

Accounts receivable, net consisted of the following at December 31, 2023 and 2022 (in thousands):


	December 31,		December 31,
	2023		2022

Accounts receivable	$	110,453	$	119,044
Less: allowance for credit losses	(4,898)		(4,327)
Accounts receivable, net	$	105,555	$	114,717

Schedule of Reconciliation of Change in Estimated Allowance for Doubtful Accounts

The following table provides a reconciliation of the changes in the allowance for estimated accounts receivable credit losses for the years ended December 31, 2023, 2022 and 2021 (in thousands):


	Year Ended December 31,
		2023		2022		2021
Balance at beginning of the period		$	4,327	$	4,249	$	3,857
Provision for expected credit losses		5,540		4,782		2,333
Write-offs and adjustments, net of recoveries		(4,969)		(4,704)		(1,941)
Balance at end of the period		$	4,898	$	4,327	$	4,249

Schedule of Inventory

Inventories consisted of the following at December 31, 2023 and 2022 (in thousands):


	December 31,
	2023		2022

Raw materials	$	42,783	$	39,207
Work-in-process	44,026		18,571
Finished goods	71,128		53,339
Total inventories	$	157,937	$	111,117

Schedule of Property and Equipment

Property and equipment, net consisted of the following at December 31, 2023 and 2022 (in thousands):


	December 31,
	2023		2022
Leasehold improvements	$	37,565	$	35,828
Office furniture and equipment	11,842		13,772
Computer equipment and software	10,340		12,330
Manufacturing and scientific equipment	69,589		62,797
Total cost	129,336		124,727
Less: accumulated depreciation and amortization	(52,794)		(56,175)
Total property and equipment, net	$	76,542	$	68,552

Schedule of Capitalized Patents


	December 31,
	2023		2022
Intangible assets, gross amount	$	12,502	$	12,502
Accumulated amortization	(9,726)		(7,875)
Intangible assets, net	$	2,776	$	4,627
Weighted average remaining amortization period (in months)	18		30

Organization and Basis of Presentation	12 Months Ended
Organization and Basis of Presentation	Dec. 31, 2023
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization and Basis of Presentation	Organization and Basis of Presentation The Company Tandem Diabetes Care, Inc. is a medical device company focused on the design, development and commercialization of technology solutions for people living with diabetes. Tandem Diabetes Care, Inc. is incorporated in the state of Delaware. Unless the context requires otherwise, the terms the “Company” or “Tandem” refer to Tandem Diabetes Care, Inc., together with its wholly-owned subsidiaries. The Company manufactures, sells, and supports insulin pump products that are designed to address the evolving needs and preferences of differentiated segments of the insulin-dependent diabetes market. The Company’s manufacturing, sales and support activities have been principally focused on the t:slim X2 Insulin Delivery System (t:slim X2), which has been the Company’s flagship pump platform and which has an advanced algorithm for managing insulin delivery, and is designed to display continuous glucose monitoring (CGM) sensor information directly on the pump home screen. In February 2024, the Company expanded its pump portfolio with the U.S. launch of Tandem Mobi. The Company’s insulin pump products are compatible with other complementary digital health offerings, such as the mobile application, cloud-based diabetes management applications and the Tandem Device Updater, a Mac- and PC-compatible tool that offers and supports remote updates of the Company’s insulin pump software from a personal computer. The Company’s insulin pump products are generally considered durable medical equipment and have an expected lifespan of at least four years. In addition to insulin pumps, the Company sells single-use products that are used together with the pumps and are replaced every few days, including cartridges for storing and delivering insulin, and infusion sets that connect the insulin pump to a user’s body. Basis of Presentation and Principles of Consolidation The Company has prepared the accompanying consolidated financial statements in accordance with accounting principles generally accepted in the United States of America, or U.S. GAAP. The statements include the accounts of Tandem Diabetes Care, Inc. and its wholly-owned subsidiaries in the United States, Canada, Netherlands, and Switzerland. All significant intercompany balances and transactions have been eliminated in consolidation. The functional currency of the Company’s foreign subsidiaries is their respective local currency. The Company translates the financial statements of its foreign subsidiaries into U.S. dollars using period-end exchange rates for assets and liabilities and average exchange rates for each period for revenue, costs and expenses. Translation related adjustments are included in other comprehensive income (loss), and in accumulated other comprehensive income (loss) in the stockholders’ equity section of the Company’s consolidated balance sheets. Foreign exchange gains or losses resulting from balances denominated in a currency other than the functional currency are recognized in interest income and other, net in the Company’s consolidated statements of operations. Reclassifications Certain prior year balances on the consolidated statements of cash flows have been reclassified to conform to the current year presentation.

CONSOLIDATED BALANCE SHEETS (Parenthetical) - $ / shares	Dec. 31, 2023	Dec. 31, 2022
Statement of Financial Position [Abstract]
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common stock, shares authorized (in shares)	200,000,000	200,000,000
Common stock, shares issued (in shares)	65,552,000	64,513,000
Common stock, shares outstanding (in shares)	65,552,000	64,513,000

Leases (Tables)

12 Months Ended

Dec. 31, 2023

Leases [Abstract]

Schedule of Lease Cost

The Company’s lease costs recorded in the consolidated statements of operations were as follows (in thousands):


	Year Ended December 31,
		2023		2022		2021
Operating lease cost		$	15,971	$	18,432	$	8,627
Short-term lease cost		108		142		90
Loss on lease termination and right-of-use asset impairment charges		11,224		5,699		—
Total lease cost		$	27,303	$	24,273	$	8,717

The weighted-average remaining lease term and weighted-average discount rate for operating leases were as follows:


	December 31, 2023		December 31, 2022
Weighted-average remaining lease term (in years)	10.2		10.8
Weighted-average discount rate used to determine operating lease liabilities	5.4	%	5.3	%

Cash paid for amounts included in the measurement of lease liabilities, representing operating cash flows, were as follows (in thousands):


	Year Ended December 31,
	2023		2022		2021
Operating lease payments	$	13,864	$	11,960	$	9,462
Operating lease termination payments	—		4,769		—
Total cash payments	$	13,864	$	16,729	$	9,462

Schedule of Future Minimum Payments Under Non-cancellable Operating Leases

Maturities of operating lease liabilities at December 31, 2023 were as follows (in thousands):


Years Ending December 31,
2024	$	17,065
2025	17,023
2026	17,068
2027	17,333
2028	13,840
Thereafter	90,004
Total undiscounted lease payments	172,333
Less: amount representing interest	(41,701)
Present value of operating lease liabilities	130,632
Less: current portion of operating lease liabilities	(17,060)
Operating lease liabilities - long-term	$	113,572

Summary of Significant Accounting Policies

12 Months Ended

Dec. 31, 2023

Accounting Policies [Abstract]

Summary of Significant Accounting Policies

There have been no material changes to the Company’s significant accounting policies during the year ended December 31, 2023, except for adding the accounting policy for sales rebates, which is included herein.

Use of Estimates

The preparation of the consolidated financial statements in conformity with U.S. GAAP requires management to make estimates and judgments that affect the reported amounts of assets, liabilities, revenues and expenses and the disclosure of contingent assets and liabilities in the Company’s consolidated financial statements and accompanying notes as of the date of the consolidated financial statements. Some of those judgments can be subjective and complex, and therefore, actual results could differ materially from those estimates under different assumptions or conditions.

Fair Value of Financial Instruments

The carrying amounts of cash and cash equivalents, accounts receivable, accounts payable, accrued expenses, and employee-related liabilities are reasonable estimates of their fair values because of the short-term nature of these assets and liabilities. Short-term investments are carried at fair value.

The Company’s convertible senior notes are carried at amortized cost on the consolidated balance sheets (see Note 7, “Debt”). The Company measures the fair value of its convertible senior notes for disclosure purposes. The Company estimated the fair value of its convertible senior notes to be $271.7 million and $260.5 million at December 31, 2023 and 2022, respectively, based on Level 2 quoted market prices as of those dates.

Cash Equivalents

The Company considers all highly liquid investments with a maturity of three months or less from the date of purchase and that can be liquidated without prior notice or penalty to be cash equivalents.

Short-Term Investments

The Company’s short-term investments are classified as available-for-sale securities. Such securities are carried at fair value as determined by prices for identical or similar securities at the balance sheet date. The Company’s short-term investments consist of Level 1 and Level 2 financial instruments in the fair value hierarchy. The net unrealized gains or losses on available-for-sale securities that are not related to credit factors are reported as a component of other comprehensive income (loss) within the statements of operations and accumulated other comprehensive income (loss) as a separate component of stockholders’ equity on the consolidated balance sheets. The Company determines realized gains or losses on the sale of available-for-sale securities using the specific identification method and includes net realized gains and losses as a component of other income or expense within the consolidated statements of operations.

The Company reviews its available-for-sale debt securities for credit losses quarterly, considering a variety of factors, including the significance of the decline in value as compared to the amortized cost basis; underlying factors contributing to a decline in the prices of securities in a single asset class; the security’s relative performance versus its peers, sector or asset class; the market and economy in general; views of external investment managers; news or financial information that has been released specific to the investee; and the outlook for the overall industry in which the investee operates. Losses on available-for-sale debt securities as a result of credit factors are recognized by recording an impairment loss as a component of other income or expense within the consolidated statements of operations and a corresponding allowance for credit losses. The Company has not recognized any impairment losses related to its short-term investments during the years ended December 31, 2023, 2022 and 2021.

Accounts Receivable

The Company grants credit to various customers in the ordinary course of business and is paid directly by customers who use its products, distributors and third-party insurance payors. The Company maintains an allowance for its current estimate of expected credit losses. Provisions for expected credit losses are estimated based on historical experience, assessment of specific customer-related risks, review of outstanding invoices, forecasts about the future, and various other assumptions and estimates that are believed to be reasonable under the circumstances, including changes to credit risks as a result of recessionary concerns, changes in discretionary spending, increased interest rates, and other macroeconomic factors. Uncollectible accounts are written off against the allowance after appropriate collection efforts have been exhausted and when it is deemed that a balance is uncollectible.

Concentration of Credit Risk

Financial instruments that potentially subject the Company to concentrations of credit risk consist primarily of cash, cash equivalents, short-term investments and accounts receivable. The Company maintains deposit accounts in federally insured financial institutions in excess of federally insured limits. The Company also maintains investments in money market funds that are not federally insured. Additionally, the Company has established guidelines regarding investment instruments and their maturities, which are designed to maintain preservation of principal and liquidity.

The following table summarizes the percentages of total sales and accounts receivable, net for customers who accounted for 10% or more of the respective amounts for the periods presented:


	Total Sales						Accounts Receivable, net
	Year Ended December 31,						December 31,
	2023		2022		2021		2023		2022
Distributor B	12.2	%	11.6	%	11.9	%	10.0	%	12.8	%
Distributor C	*		*		*		10.5	%	*
Distributor D	*		*		*		10.6	%	10.4	%
Distributor E	10.8	%	14.4	%	14.0	%	11.5	%	16.2	%

* Amount related to the respective customer represented less than 10% for the period presented.

Valuation of Inventories

Inventories are valued at the lower of cost or net realizable value, determined by the first-in, first-out method. Inventory is recorded using standard cost, including material, labor and overhead costs. The Company periodically reviews inventories for potential impairment and adjusts inventory for potentially excess or obsolete goods to state inventories at their net realizable value. Factors influencing these adjustments include quantities on hand and firm purchase commitments, expectations of future use, judgments based on quality control testing data and assessments of the likelihood of scrapping or obsoleting certain inventories based on future demand for its products and market conditions.

Long-Lived Assets

Property and Equipment

Property and equipment, which primarily consist of office furniture and equipment, manufacturing equipment, scientific equipment, computer equipment, and leasehold improvements, are stated at cost, less accumulated depreciation. Property and equipment are depreciated over the estimated useful lives of the assets, generally three to seven years, using the straight-line method. Leasehold improvements and related equipment are amortized over the lesser of the estimated useful lives of the assets or the remaining lease term, unless there is a transfer of title or purchase option that is reasonably certain to be exercised. Maintenance and repair costs are expensed as incurred.

Operating Lease Right-of-Use Assets and Liabilities

Operating lease right-of-use assets represent the Company’s right to use an underlying asset for the lease term and lease liabilities represent its obligation to make lease payments arising from the lease. Operating lease right-of-use assets and liabilities are recognized when the Company takes possession of the leased property (Commencement Date) based on the present value of lease payments over the lease term. For lease agreements entered into or reassessed after the adoption of ASC 842 Leases, the Company combines lease and non-lease components. Rent expense on noncancelable leases containing known future scheduled rent increases is recorded on a straight-line basis over the term of the respective leases beginning on the Commencement Date. The difference between rent expense and rent paid is accounted for as a component of operating lease right-of-use assets on the Company’s consolidated balance sheets. Landlord improvement allowances and other similar lease incentives are recorded as a reduction of the right-of-use leased assets, and are amortized on a straight-line basis as a reduction to operating lease costs.

Intangible Assets Subject to Amortization

Finite-lived intangible assets are recorded at cost, net of accumulated amortization and, if applicable, impairment charges. Amortization of finite-lived intangible assets is recognized over their estimated useful lives on a straight-line basis. The Company did not recognize any intangible asset impairment losses during the years ended December 31, 2023, 2022 and 2021.

Impairment of Long-Lived Assets

Long-lived assets, such as property and equipment, right-of-use lease assets, and acquired intangible assets subject to amortization, are reviewed for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable. If circumstances require a long-lived asset or asset group be tested for possible impairment, the Company first compares undiscounted cash flows expected to be generated by that asset or asset group to its carrying amount. If the carrying amount of the long-lived asset or asset group is not recoverable on an undiscounted cash flow basis, an impairment is recognized to the extent that the carrying amount exceeds its fair value. Fair value is determined using unobservable (Level 3) inputs, including discounted cash flow models, future estimated sublease income, and third-party independent appraisals, as considered necessary. There is uncertainty in the projected undiscounted future cash flows used in the Company’s impairment review analysis, which requires the use of estimates and assumptions. If actual performance does not achieve the projections, or if the assumptions used change in the future, the Company may be required to recognize additional impairment charges in future periods. Other than the impairment of operating lease right-of-use assets and related leasehold improvements and furniture and fixtures recognized in 2023 and 2022 (see Note 6, “Leases”), there were no impairments of long-lived assets, including acquired intangible assets, during the years ended December 31, 2023, 2022 and 2021.

Strategic Investments

The Company held equity investments totaling $10.1 million and $16.4 million in two separate private companies at December 31, 2023 and 2022, respectively, each of which represented less than 5% of the outstanding equity of the respective company as of the date of investment. The investments are carried at cost minus impairment, if any, adjusted for changes in observable prices. The Company monitors these investments to evaluate whether any increase or decline in its value has occurred, based on the implied value of recent company financings, public market prices of comparable companies and general market conditions. The investments were included as a component of other long-term assets on the consolidated balance sheets at December 31, 2023 and 2022.

In November 2023, the Company made an additional investment of approximately $22.3 million in subordinated convertible notes of one of its private investee companies. The subordinated notes are convertible into equity of the private company upon certain qualifying events, including at their final maturity in 2024. The subordinated convertible notes are non-interest bearing, and are only repayable before conversion into equity upon a change in control of the private company. At December 31, 2023, the $22.3 million subordinated convertible notes investment was included as a component of other long-term assets on the consolidated balance sheet.

Revenue Recognition

Revenue is generated primarily from sales of insulin pumps, single-use insulin cartridges and infusion sets to individual customers with third-party insurance coverage and through a network of distributors that resell the products to insulin-dependent diabetes customers. The Company recognizes revenue when it transfers control of the promised goods or services to customers in an amount that reflects the consideration to which the Company expects to be entitled in exchange for those goods or services, net of estimated rebates and returns.

Revenue Recognition for Arrangements with Multiple Performance Obligations

The Company considers the individual deliverables in its product offering to be separate performance obligations. The transaction price is determined based on the consideration expected to be received, based either on the stated value in contractual arrangements or the estimated cash to be collected in non-contracted arrangements. The Company allocates the consideration to the individual performance obligations and recognizes the consideration based on when the performance obligation is satisfied, considering whether or not this occurs at a point in time or over time. Generally, insulin pumps, cartridges, infusion sets, and accessories are deemed performance obligations that are satisfied at a point in time when the customer obtains control of the promised good, which typically is upon shipment for our distributor arrangements and upon receipt for sales directly to individual customers. Complementary products, such as t:connect, Tandem Source and the Tandem Device Updater, are considered distinct performance obligations that are satisfied over time, as access and support for these products is provided throughout the typical four-year warranty period of the insulin pumps. Accordingly, revenue related to the complementary products is deferred and recognized over a four-year period. Where there is no standalone value for the complementary product, the Company determines its value by applying the expected cost plus a margin approach and then allocates the residual to the insulin pumps.

Revenue Recognition for Tandem Choice Program

In September 2022, the Company launched a new technology access program referred to as Tandem Choice, that provides eligible, in-warranty t:slim X2 customers in the United States with the flexibility to obtain the newest hardware platform, Tandem Mobi, when it becomes commercially available. Participating customers have the right to purchase the alternative Tandem pump for a fee, referred to as Choice Right. Tandem Choice expires on December 31, 2024. The program was determined to create a material right for which a portion of each t:slim X2 pump transaction price was allocated and deferred.

During the third and fourth quarters of 2023, the Company reduced the fee for the Tandem Choice program. The change in the program resulted in an increase to the amount of the transaction price allocated to the material right as the Company expects more customers to exercise the right as compared to the prior existing program price.

For purposes of evaluating Tandem Choice in accordance with ASC 606, the Company has determined that the ability for a customer to upgrade to a new technology represents a material right because the pricing inherent in such option provides the customer with a discount that is incremental to the range of discounts that would otherwise be granted for the related goods and services to comparable customers. The standalone selling price for the Choice Right was estimated based on the adjusted market assessment approach and contemplated the likelihood that the respective option will be exercised. At December 31, 2023 and 2022, $30.6 million and $6.8 million, respectively, were allocated to the material right provided to customers and recorded in current deferred revenue on the consolidated balance sheets.

Sales Rebates

The Company is subject to certain rebates on pricing programs with managed care organizations, such as governmental and third-party commercial payors. The Company estimates provisions for rebates based on contractual arrangements, estimates of products sold subject to rebate, known events or trends and channel inventory data. At December 31, 2023, estimated sales rebates of $8.5 million were recorded on the consolidated balance sheet, of which $8.0 million was included in other long-term liabilities as the estimated payment due date was beyond twelve months from the balance sheet date. Accordingly, actual rebates paid may differ from estimated amounts recorded in the accompanying consolidated financial statements. The Company did not provide sales rebates before the fourth quarter of 2023.

Warranty Reserve

The Company generally provides a four-year warranty on its insulin pumps to end-user customers and may replace any pumps that do not function as intended in accordance with the product specifications within the warranty period. Additionally, the Company offers a six-month warranty on single-use insulin cartridges and infusion sets. Estimated warranty costs are recorded at the time of shipment, and the Company reevaluates the estimate of the warranty reserve obligation at each reporting period. Warranty costs are estimated primarily based on the current expected product replacement cost and expected replacement rates using historical experience. Insulin pumps returned to the Company may be refurbished and redeployed. Experience has shown that initial data for any given pump version or pump platform may be insufficient; therefore, the Company’s process relies on long-term historical averages until sufficient data are available. As actual experience becomes available, the Company uses the data to update the historical averages. The Company may make further adjustments to the warranty reserve when deemed appropriate, giving additional consideration to revised future expectations of performance based on enhanced hardware components, or new features and capabilities that may become available through Tandem Device Updater. Warranty expense is recorded as a component of cost of sales in the consolidated statements of operations.

The following table provides a reconciliation of the changes in product warranty liabilities for the years ended December 31, 2023, 2022 and 2021 (in thousands):


	Year Ended December 31,
		2023		2022		2021
Balance at beginning of the period		$	36,537	$	30,401	$	22,075
Provision for warranties issued during the period		35,690		32,699		27,604
Settlements made during the period		(32,617)		(25,447)		(18,768)
Decreases in warranty estimates		(2,437)		(1,116)		(510)
Balance at end of the period		$	37,173	$	36,537	$	30,401

As of December 31, 2023 and 2022, total product warranty reserves were included in the following consolidated balance sheet accounts (in thousands):


	December 31, 2023		December 31, 2022

Other current liabilities	$	18,135	$	17,280
Other long-term liabilities	19,038		19,257
Total warranty reserve	$	37,173	$	36,537

Stock-Based Compensation

Stock-based compensation cost is measured at the grant date based on the estimated fair value of the award, and the portion that is ultimately expected to vest is recognized as compensation expense over the requisite service period on a straight-line basis. The Company estimates the fair value of stock options issued under the Company’s stock incentive plans, and the fair value of the employees’ purchase rights under the Company’s Employee Stock Purchase Plan (ESPP), using the Black-Scholes option pricing model on the date of grant. The Black-Scholes option pricing model requires the use of assumptions about a number of variables, including stock price volatility, expected term, dividend yield and risk-free interest rate (see Note 8, “Stockholders’ Equity”). The fair value of restricted stock unit (RSU) awards issued under the Company’s stock incentive plans that vest solely based on service, is estimated based on the fair market value of the underlying stock on the date of grant. The fair value of RSU awards that vest based upon the Company’s actual performance relative to predefined performance metrics, and the awardee’s continuing service through the measurement date, is generally estimated based on the fair market value of the underlying stock on the date of grant and the probability that the specified performance criteria will be met. At each reporting period, the Company reassesses the probability of the achievement of such performance metrics. Any expense change resulting from an adjustment in the estimated shares to be released is recorded in the period of adjustment.

Shipping and Handling Expenses

Shipping and handling expenses associated with product delivery are included within cost of sales in the Company’s statements of operations. Amounts billed to a customer for shipping and handling are reported as revenues.

Research and Development Costs

All research and development costs are charged to expense as incurred. Such costs include personnel-related costs, including stock-based compensation, supplies, license fees, development prototypes, outside design and testing services, depreciation, allocated facilities and information services, clinical trial costs, milestone payments under the Company’s licensing, development and commercialization agreements, and other indirect costs.

Acquired In-Process Research and Development Expenses

Acquired in-process research and development (IPR&D) expenses reflect the costs of externally developed IPR&D projects acquired directly in a transaction other than a business combination that do not have an alternative future use, including the initial costs of rights to IPR&D projects. The acquired IPR&D is expensed on acquisition date. Future costs to develop these IPR&D projects are recorded in research and development expenses on the consolidated statements of operations as incurred.

Income Taxes

The Company uses the asset and liability method of accounting for income taxes. Deferred tax assets or liabilities are recognized based on the temporary differences between financial statement and income tax bases of assets and liabilities using enacted tax rates in effect for the years in which the differences are expected to reverse. Tax law and rate changes are reflected in income in the period such changes are enacted. A valuation allowance is recorded when it is more likely than not that some of the deferred tax assets will not be realized. The evaluation of the need for a valuation allowance is performed on a jurisdiction-by-jurisdiction basis, and includes a review of all available positive and negative evidence. Factors reviewed include projections of pre-tax book income for the foreseeable future, determination of cumulative pre-tax book income after permanent differences, earnings history, and reliability of forecasting. The Company will continue to assess the need for a valuation allowance on its deferred tax assets by evaluating both positive and negative evidence that may exist. Any adjustment to the net deferred tax asset valuation allowance would be recorded in the statement of operations for the period that the adjustment is determined to be required.

The Company’s income tax returns are based on calculations and assumptions that are subject to examination by the Internal Revenue Service and other tax authorities. In addition, the calculation of the Company’s tax liabilities involves dealing with uncertainties in the application of complex tax regulations. The Company recognizes liabilities for uncertain tax positions using a two-step approach. The first step is to evaluate the tax position for recognition by determining if the weight of available evidence indicates that it is more likely than not that the position will be sustained on audit, including resolution of related appeals or litigation processes, if any. The second step is to measure the tax benefit as the largest amount that is more than 50% likely to be realized upon settlement. While the Company believes it has appropriate support for the positions taken on its tax returns, the Company regularly assesses the potential outcomes of examinations by tax authorities in determining the adequacy of its provision for income taxes. The Company continually assesses the likelihood and amount of potential revisions and adjusts the income tax provision, income taxes payable and deferred taxes in the period in which the facts that give rise to a revision become known. The Company includes interest and penalties related to income taxes, including unrecognized tax benefits, within income tax expense.

Comprehensive Income (Loss)

All components of comprehensive income (loss), including net income (loss), are reported in the consolidated financial statements in the period in which they are recognized. Comprehensive income (loss) is defined as the change in equity during a period from transactions and other events and circumstances from non-owner sources, including unrealized gains and losses on marketable securities and foreign currency translation adjustments.

Net Income (Loss) Per Share

Basic net income (loss) per share is calculated by dividing the net income or loss by the weighted average number of common shares outstanding for the period, without consideration for common stock equivalents. Diluted net income (loss) per share reflects the potential dilution that would occur if securities exercisable for or convertible into common stock were exercised for or converted into common stock. Dilutive common share equivalents are comprised of stock options and unvested RSUs outstanding under the Company’s stock incentive plans, potential awards to be granted pursuant to the ESPP, and common stock warrants, each calculated using the treasury stock method; and shares issuable upon conversion of the convertible senior notes calculated using the if-converted method.


	Year Ended December 31,
	2023		2022		2021
Net income (loss) - basic and diluted	$	(222,611)	$	(94,594)	$	15,566



Weighted average shares outstanding - basic	64,969		64,146		63,000
Dilutive common share equivalents:
Options to purchase common stock	—		—		1,129
Unvested restricted stock units	—		—		62
Warrants to purchase common stock	—		—		157
Awards to be granted under the ESPP	—		—		1

Weighted average shares outstanding - diluted	64,969		64,146		64,349


	Year Ended December 31,
		2023	2022	2021
Options to purchase common stock		135	1,138	3,124
Unvested restricted stock units		2,089	1,118	—
Warrants to purchase common stock		194	194	1
Awards granted under the ESPP		14	8	—
Convertible senior notes (if-converted)		2,554	2,554	2,554
		4,986	5,012	5,679

Employee Benefits - Additional Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Retirement Benefits [Abstract]
Minimum age of employees for defined contribution plan	18 years
Contribution by company	$ 4.2	$ 4.2

Stockholders' Equity

12 Months Ended

Dec. 31, 2023

Equity [Abstract]

Stockholders' Equity

Stockholders’ Equity

Shares Reserved for Future Issuance

The following shares of the Company's common stock were reserved for future issuance at December 31, 2023 (in thousands):


Shares reserved for issuance upon conversion of Convertible Senior Notes			2,554
Shares underlying outstanding warrants			194
Shares underlying outstanding stock options			3,896
Shares underlying unvested restricted stock units			3,176
Shares authorized for issuance pursuant to awards granted under the ESPP			454
Shares authorized for future equity award grants			702
Total			10,976

Common Stock Warrants

Warrants outstanding to purchase shares of the Company's common stock as of December 31, 2023 were as follows:

Issue Date

Exercise Price Per Share

Warrants Outstanding

Expiration Date of Warrants Outstanding

March 2017

$23.50

193,788

March 2027

Each warrant allows the holder to purchase one share of common stock at the per share exercise price of the warrant.

Stock Incentive Plans

In May 2023, the Company’s stockholders approved the 2023 Long-Term Incentive Plan (2023 Plan), under which 2,602,184 shares of common stock were initially reserved for issuance. Under the 2023 Plan, the Company may grant stock options, stock appreciation rights, restricted stock and restricted stock units to individuals who are then employees, officers, directors or consultants of the Company. The 2023 Plan replaced the Company’s Amended and Restated 2013 Stock Incentive Plan (2013 Plan), and no further equity awards will be granted under the 2013 Plan.

Stock Options

The maximum term of stock options granted under the Company’s active plans is ten years. Stock options have an exercise price equal to the closing price of the Company's common stock on the applicable award date. Stock options granted before the second quarter of 2022 generally vest over a four-year period as to 25% of the underlying shares on the first anniversary of the grant date, with the balance of the options vesting monthly over the following three years. Stock options granted during the second quarter of 2022 and thereafter vest over a three-year period as to 33% of the underlying shares on the first anniversary of the grant date, with the balance of the options vesting monthly over the following two years.

The following table summarizes stock option activities under the Company’s stock incentive plans:


	Total Stock Options	Weighted- Average Exercise Price Per Share		Weighted- Average Remaining Contractual Life (in years)	Aggregate Intrinsic Value (in thousands)
Outstanding at December 31, 2020	5,803,505	$	52.08	7.90	$	268,649
Granted	355,008	$	86.68
Exercised	(1,128,791)	$	37.05		$	86,149
Canceled/forfeited/expired	(214,876)	$	76.29		$	6,963
Outstanding at December 31, 2021	4,814,846	$	57.08	7.07	$	452,081
Granted	83,008	$	65.28
Exercised	(280,275)	$	32.58		$	13,473
Canceled/forfeited/expired	(175,266)	$	77.93		$	2,143
Outstanding at December 31, 2022	4,442,313	$	57.95	6.12	$	30,236
Granted	—	$	—
Exercised	(72,536)	$	17.86		$	1,400
Canceled/forfeited/expired	(473,773)	$	90.14		$	95
Outstanding at December 31, 2023	3,896,004	$	54.79	5.30	$	11,703
Vested and expected to vest at December 31, 2023	3,890,496	$	54.75	5.30	$	11,703
Exercisable at December 31, 2023	3,675,678	$	53.11	5.19	$	11,703

Restricted Stock Units

Restricted stock units (RSUs) have a grant value equal to the closing price of the Company’s common stock on the award date. RSUs granted before March 2022 generally vest over a four-year period based only on continuous service as to 25% of the underlying shares on the first anniversary of the award, with the balance of the RSUs vesting quarterly over the following three years. RSUs granted in March 2022 and thereafter generally vest over a three-year period based on continuous service to the Company as to 33% of the underlying shares on the first anniversary of the award, with the balance of the RSUs vesting quarterly over the following two years. In addition, the Company granted 110,074, 53,662 and 25,674 performance-based RSUs during the years ended December 31, 2023, 2022 and 2021, respectively. The Company estimated the fair value of performance-based RSUs at the date of grant using the intrinsic value method and the probability that the specified performance metrics will be met. These awards vest upon the Company’s actual performance relative to predefined performance metrics and subject to the awardee’s continuous service through the respective December 31, 2024 and 2025 measurement dates as defined in the award agreements. For certain performance-based RSUs with market-based criteria, the Company used a Monte Carlo methodology to estimate the fair value at the date of grant.

The following table summarizes RSU activities, which includes performance-based RSUs, for the Company’s stock incentive plans:


	Total RSUs	Weighted-Average Grant Date Fair Value		Aggregate Intrinsic Value (in thousands)
Unvested awards outstanding at December 31, 2020	132,802	$	82.82	$	12,706
Granted	564,034	$	96.37
Vested	(53,957)	$	82.74
Canceled/forfeited	(32,148)	$	87.21
Unvested awards outstanding at December 31, 2021	610,731	$	95.08	$	91,927
Granted	1,542,859	$	67.09
Vested	(202,215)	$	91.99
Canceled/forfeited	(117,543)	$	84.20
Unvested awards outstanding at December 31, 2022	1,833,832	$	72.57	$	82,431
Granted	2,359,907	$	28.13
Vested	(735,155)	$	73.17
Canceled/forfeited	(282,425)	$	59.17
Unvested awards outstanding at December 31, 2023	3,176,159	$	40.61	$	93,951
Awards expected to vest at December 31, 2023	3,088,745	$	40.50	$	91,365

The aggregate fair value of RSUs that vested during the years ended December 31, 2023, 2022 and 2021 was $21.2 million, $12.7 million, and $5.1 million, respectively, which represents the market value of the Company’s common stock on the date the RSUs vested. The number of RSUs vested includes shares of common stock the Company withheld on behalf of employees to satisfy the minimum statutory tax withholding requirements. RSUs that are expected to vest are net of estimated future forfeitures.

Employee Stock Purchase Plan

The Company’s Employee Stock Purchase Plan (ESPP) was approved by the Board in October 2013. The ESPP enables eligible employees to purchase shares of the Company’s common stock using their after-tax payroll deductions, subject to certain conditions. The ESPP is intended to qualify as an “employee stock purchase plan” within the meaning of Section 423 of the Code. Eligible employees may contribute, through payroll deductions, up to 15% of their earnings for the purchase of common stock under the ESPP. The purchase price of common stock under the ESPP is the lesser of: (a) 85% of the fair market value of a share of the Company’s common stock on the first date of an offering or (b) 85% of the fair market value of a share of the Company’s common stock on the date of purchase. Generally, offerings under the ESPP consist of a two-year offering period with four six-month purchase periods which begin in May and November of each year.

During the years ended December 31, 2023, 2022 and 2021, 499,431, 262,936 and 172,694 shares of our common stock, respectively, were purchased under the ESPP for proceeds of $10.7 million, $12.7 million and $11.1 million, respectively.

Stock-Based Compensation

The following table summarizes the allocation of stock-based compensation expense included in the consolidated statements of operations for all stock-based compensation arrangements (in thousands):


	Year Ended December 31,
		2023		2022		2021
Cost of sales		$	6,212	$	7,685	$	6,434
Selling, general and administrative		56,304		57,196		43,567
Research and development		25,561		20,037		10,751
Total stock-based compensation expense		$	88,077	$	84,918	$	60,752

The total stock-based compensation expense capitalized as part of the cost of the Company’s inventories was $2.0 million at December 31, 2023, and $1.1 million at December 31, 2022.

At December 31, 2023, the total unamortized stock-based compensation expense of approximately $116.7 million will be recognized over the remaining weighted average vesting term of approximately 1.9 years.

The Company estimates the fair value of stock options using the Black-Scholes option pricing model on the grant date. The assumptions used in the Black-Scholes option pricing model were as follows:


		Stock Options
	Year Ended December 31,
		2023	2022			2021
Weighted average grant date fair value (per share)		N/A	$	42.16		$	56.89
Risk-free interest rate		N/A	2.7		%	1.0		%
Dividend yield		N/A	0.0		%	0.0		%
Expected volatility		N/A	72.0		%	75.1		%
Expected term (in years)		N/A	5.8			6.1

The Company records stock-based compensation expense associated with the ESPP using the Black-Scholes option pricing model. Valuations are performed on the grant date at the beginning of the purchase period, which generally occurs in May and November of each year. The assumptions used in the Black-Scholes option pricing model for the ESPP were as follows:


					ESPP
	Year Ended December 31,
		2023			2022			2021
Weighted average grant date fair value (per share)		$	10.35		$	21.89		$	38.19
Risk-free interest rate		4.9		%	3.4		%	0.2		%
Dividend yield		0.0		%	0.0		%	0.0		%
Expected volatility		63.9		%	56.9		%	44.2		%
Expected term (in years)		1.3			1.3			1.3

Risk-free Interest Rate. The risk-free interest rate assumption was based on the United States Treasury’s rates for U.S. Treasury zero-coupon bonds with maturities similar to those of the expected term of the award being valued.

Expected Dividend Yield. The dividend yield is zero because the Company has never declared or paid any cash dividends and does not presently plan to pay cash dividends in the foreseeable future.

Expected Volatility. The expected volatility was estimated based on a weighted-average of the Company’s actual historical volatility of its common stock measured over the expected term.

Expected Term. The Company utilized the simplified method for estimating the expected term of stock option grants. Under this approach, the weighted-average expected term is presumed to be the average of the vesting term and the contractual term of the option. The Company estimates the expected term of the ESPP using expected life for each tranche during the two-year offering period.

The Company also estimates forfeitures at the time of grant, and revises those estimates in subsequent periods if actual forfeitures differ from its estimates. Historical data was used to estimate pre-vesting option forfeitures and record stock-based compensation expense only for those awards that are expected to vest.

- Definition

The entire disclosure for equity.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481112/505-10-50-13

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Subparagraph (h)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481112/505-10-50-13

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 14
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481112/505-10-50-14

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
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-Name Accounting Standards Codification
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-Subparagraph (a)
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-URI https://asc.fasb.org//1943274/2147481062/946-235-50-2

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 235
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481062/946-235-50-2

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 505
-Name Accounting Standards Codification
-Section 50
-Paragraph 6
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481004/946-505-50-6

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Topic 815
-SubTopic 40
-Name Accounting Standards Codification
-Section 50
-Paragraph 6
-Subparagraph (a)
-Publisher FASB
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Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.3-04)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480008/505-10-S99-1

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Topic 235
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-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08(e)(1))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480678/235-10-S99-1

Reference 10: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 505
-Name Accounting Standards Codification
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-URI https://asc.fasb.org//505/tableOfContent

Reference 11: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
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-Name Accounting Standards Codification
-Section 50
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Reference 12: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
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-Name Accounting Standards Codification
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-Publisher FASB
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Reference 13: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
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-Section 50
-Paragraph 13
-Subparagraph (i)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481112/505-10-50-13

Reference 14: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
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-Name Accounting Standards Codification
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Reference 15: http://www.xbrl.org/2003/role/disclosureRef
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Reference 16: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
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Reference 17: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
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-Publisher FASB
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Reference 18: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
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-Subparagraph (b)
-Publisher FASB
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Reference 19: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
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-Name Accounting Standards Codification
-Section 50
-Paragraph 18
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481112/505-10-50-18

+ Details

Debt (Tables)

12 Months Ended

Dec. 31, 2023

Debt Disclosure [Abstract]

Schedule of Convertible Notes

The net carrying amount of the Notes on the consolidated balance sheets consisted of the following (in thousands):


	December 31, 2023		December 31, 2022
Principal amount	$	287,500	$	287,500
Unamortized debt issuance costs	(2,465)		(4,268)
Net carrying amount	$	285,035	$	283,232

Schedule of Interest Expense Recognized

The following table details interest expense related to the Notes recognized for the years ended December 31, 2023, 2022 and 2021 (in thousands):


	Year Ended December 31,
		2023		2022		2021
Contractual interest expense(1)		$	7,565	$	4,313	$	4,313
Amortization of debt issuance costs		1,803		1,896		1,727

Total interest expense		$	9,368	$	6,209	$	6,040

(1) Contractual interest expense for the year ended December 31, 2023 includes $3.3 million of additional interest as discussed above.

Summary of Significant Accounting Policies - Additional Information (Details)	1 Months Ended	12 Months Ended
	Nov. 30, 2023 USD ($)	Dec. 31, 2023 USD ($) investment	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)
Summary Of Significant Accounting Policies [Line Items]
Operating lease termination and impairment charges		$ 0	$ 0	$ 0
Investment owned at cost		$ 10,100,000	16,400,000
Number of investments held by the company \| investment		2
Ownership interest of investment owned		5.00%
Payments to acquire investments	$ 22,300,000
Other long-term assets		$ 40,336,000	23,631,000
Guarantee liability current		30,600,000	6,800,000
Estimated sales rebates		8,500,000
Estimated sales rebates, noncurrent		8,000,000.0
Notes Receivable
Summary Of Significant Accounting Policies [Line Items]
Other long-term assets		$ 22,300,000
Minimum
Summary Of Significant Accounting Policies [Line Items]
Estimated useful lives of the assets		3 years
Maximum
Summary Of Significant Accounting Policies [Line Items]
Estimated useful lives of the assets		7 years
Insulin Pump
Summary Of Significant Accounting Policies [Line Items]
Warranty period offered		4 years
Slim cartridges and infusion sets
Summary Of Significant Accounting Policies [Line Items]
Warranty period offered		6 months
Convertible senior notes \| Level 2 \| Convertible senior notes
Summary Of Significant Accounting Policies [Line Items]
Convertible senior notes, fair value		$ 271,700,000	$ 260,500,000

Business Segment and Geographic Information

12 Months Ended

Dec. 31, 2023

Segment Reporting [Abstract]

Business Segment and Geographic Information

Segment Reporting

Operating segments are identified as components of an enterprise about which discrete financial information is available for evaluation by the chief operating decision-maker (CODM) in making decisions regarding resource allocation and assessing performance. The Company is organized based on its current product portfolio, which consists primarily of insulin pumps, single-use insulin cartridges and infusion sets for the storage and delivery of insulin. The Company views its operations and manages its business as one segment and a single reporting unit because key operating decisions and resource allocations are made by the CODM using consolidated financial data.

Disaggregation of Revenue

The Company primarily sells its products through national and regional distributors in the United States on a non-exclusive basis, and through distribution partners outside the United States. In the United States and Canada, the Company also uses a direct sales force. The Company disaggregates its revenue by geography and by major sales channel as management believes these categories best depict how the nature, amount and timing of revenues and cash flows are affected by economic factors.

Revenues by Geographic Region and Customer Sales Channel

During the years ended December 31, 2023, 2022 and 2021, no individual country outside the United States generated revenue that represented more than 10% of total revenue. The table below sets forth revenues for the Company’s two primary geographical markets, based on the geographic location to which its products are shipped (in thousands):


	Year Ended December 31,
		2023		2022		2021
United States		$	554,878	$	588,765	$	524,907
Outside the United States		192,840		212,452		177,892
Total Sales		$	747,718	$	801,217	$	702,799

Sales to distributors accounted for 64%, 65%, and 67% of the Company’s total United States sales for the years ended December 31, 2023, 2022 and 2021, respectively. Sales to distributors accounted for 99%, 96%, and 95% of the Company’s total sales outside the United States for the years ended December 31, 2023, 2022 and 2021, respectively.

- Definition

The entire disclosure for reporting segments including data and tables. Reportable segments include those that meet any of the following quantitative thresholds a) it's reported revenue, including sales to external customers and intersegment sales or transfers is 10 percent or more of the combined revenue, internal and external, of all operating segments b) the absolute amount of its reported profit or loss is 10 percent or more of the greater, in absolute amount of 1) the combined reported profit of all operating segments that did not report a loss or 2) the combined reported loss of all operating segments that did report a loss c) its assets are 10 percent or more of the combined assets of all operating segments.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 22
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-22

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 15
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-15

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
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-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-31

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
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-Section 50
-Paragraph 32
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-32

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
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-Name Accounting Standards Codification
-Section 50
-Paragraph 42
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-42

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
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-Section 50
-Paragraph 32
-Subparagraph (f)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-32

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 40
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-40

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-Name Accounting Standards Codification
-Publisher FASB
-URI https://asc.fasb.org//280/tableOfContent

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 26
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-26

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 34
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-34

Reference 11: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
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-Section 50
-Paragraph 41
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-41

Reference 12: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
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-Name Accounting Standards Codification
-Section 50
-Paragraph 21
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-21

Reference 13: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 21
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-21

Reference 14: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 32
-Subparagraph (e)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-32

+ Details

Fair Value Measurements (Tables)

12 Months Ended

Dec. 31, 2023

Fair Value Disclosures [Abstract]

Schedule of Financial Assets and Liabilities Measured at Fair Value on Recurring Basis

The following table presents information about the Company’s financial assets and liabilities measured at fair value on a recurring basis as of December 31, 2023 and 2022, and indicates the fair value hierarchy of the valuation techniques used by the Company to determine such fair value (in thousands):


	Fair Value Measurements at December 31, 2023
	Total		Level 1		Level 2		Level 3
Assets
Cash equivalents(1)	$	48,033	$	48,033	$	—	$	—
U.S. Government-sponsored enterprises	182,154		—		182,154		—
U.S. Treasury securities	115,004		115,004		—		—
Commercial paper	72,511		—		72,511		—
Corporate debt securities	39,375		—		39,375		—

Total assets	$	457,077	$	163,037	$	294,040	$	—


	Fair Value Measurements at December 31, 2022
	Total		Level 1		Level 2		Level 3
Assets
Cash equivalents(1)	$	150,742	$	150,742	$	—	$	—
U.S. Government-sponsored enterprises	100,008		—		100,008		—
U.S. Treasury securities	211,161		211,161		—		—
Commercial paper	112,610		—		112,610		—
Corporate debt securities	18,114		—		18,114		—
Supranational bonds	2,491		—		2,491		—
Total assets	$	595,126	$	361,903	$	233,223	$	—

(1)Generally, cash equivalents include money market funds and investments with a maturity of three months or less from the date of purchase.

Income Taxes - Income Tax Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Income Tax Disclosure [Abstract]
Income tax benefit at federal statutory rate	$ (46,253)	$ (19,499)	$ 3,339
State income tax, net of federal benefit	(1,313)	(926)	(254)
Warrants revaluation	0	(31)	356
Research and development credits	(6,283)	(6,263)	(5,703)
Section 382 limitation	(5)	0	(97)
Stock-based compensation	14,904	2,282	(7,609)
Officers' compensation	1,547	2,931	4,024
Recognition of acquired deferred tax assets	(5,048)	0	0
Acquired IPR&D expenses	14,938	6,518	0
Other	1,074	962	124
Change in valuation allowance	28,796	15,768	6,155
Income tax expense	$ 2,357	$ 1,742	$ 335

Organization and Basis of Presentation (Policies)	12 Months Ended
Organization and Basis of Presentation (Policies)	Dec. 31, 2023
Organization, Consolidation and Presentation of Financial Statements [Abstract]
The Company	The Company Tandem Diabetes Care, Inc. is a medical device company focused on the design, development and commercialization of technology solutions for people living with diabetes. Tandem Diabetes Care, Inc. is incorporated in the state of Delaware. Unless the context requires otherwise, the terms the “Company” or “Tandem” refer to Tandem Diabetes Care, Inc., together with its wholly-owned subsidiaries. The Company manufactures, sells, and supports insulin pump products that are designed to address the evolving needs and preferences of differentiated segments of the insulin-dependent diabetes market. The Company’s manufacturing, sales and support activities have been principally focused on the t:slim X2 Insulin Delivery System (t:slim X2), which has been the Company’s flagship pump platform and which has an advanced algorithm for managing insulin delivery, and is designed to display continuous glucose monitoring (CGM) sensor information directly on the pump home screen. In February 2024, the Company expanded its pump portfolio with the U.S. launch of Tandem Mobi. The Company’s insulin pump products are compatible with other complementary digital health offerings, such as the mobile application, cloud-based diabetes management applications and the Tandem Device Updater, a Mac- and PC-compatible tool that offers and supports remote updates of the Company’s insulin pump software from a personal computer. The Company’s insulin pump products are generally considered durable medical equipment and have an expected lifespan of at least four years. In addition to insulin pumps, the Company sells single-use products that are used together with the pumps and are replaced every few days, including cartridges for storing and delivering insulin, and infusion sets that connect the insulin pump to a user’s body.
Basis of Presentation and Principles of Consolidation	Basis of Presentation and Principles of Consolidation The Company has prepared the accompanying consolidated financial statements in accordance with accounting principles generally accepted in the United States of America, or U.S. GAAP. The statements include the accounts of Tandem Diabetes Care, Inc. and its wholly-owned subsidiaries in the United States, Canada, Netherlands, and Switzerland. All significant intercompany balances and transactions have been eliminated in consolidation. The functional currency of the Company’s foreign subsidiaries is their respective local currency. The Company translates the financial statements of its foreign subsidiaries into U.S. dollars using period-end exchange rates for assets and liabilities and average exchange rates for each period for revenue, costs and expenses. Translation related adjustments are included in other comprehensive income (loss), and in accumulated other comprehensive income (loss) in the stockholders’ equity section of the Company’s consolidated balance sheets. Foreign exchange gains or losses resulting from balances denominated in a currency other than the functional currency are recognized in interest income and other, net in the Company’s consolidated statements of operations.
Reclassifications	Reclassifications Certain prior year balances on the consolidated statements of cash flows have been reclassified to conform to the current year presentation.
Use of Estimates	Use of Estimates The preparation of the consolidated financial statements in conformity with U.S. GAAP requires management to make estimates and judgments that affect the reported amounts of assets, liabilities, revenues and expenses and the disclosure of contingent assets and liabilities in the Company’s consolidated financial statements and accompanying notes as of the date of the consolidated financial statements. Some of those judgments can be subjective and complex, and therefore, actual results could differ materially from those estimates under different assumptions or conditions.
Accounts Receivable	Accounts Receivable The Company grants credit to various customers in the ordinary course of business and is paid directly by customers who use its products, distributors and third-party insurance payors. The Company maintains an allowance for its current estimate of expected credit losses. Provisions for expected credit losses are estimated based on historical experience, assessment of specific customer-related risks, review of outstanding invoices, forecasts about the future, and various other assumptions and estimates that are believed to be reasonable under the circumstances, including changes to credit risks as a result of recessionary concerns, changes in discretionary spending, increased interest rates, and other macroeconomic factors. Uncollectible accounts are written off against the allowance after appropriate collection efforts have been exhausted and when it is deemed that a balance is uncollectible.
Fair Value of Financial Instruments	Fair Value of Financial Instruments The carrying amounts of cash and cash equivalents, accounts receivable, accounts payable, accrued expenses, and employee-related liabilities are reasonable estimates of their fair values because of the short-term nature of these assets and liabilities. Short-term investments are carried at fair value. The Company’s convertible senior notes are carried at amortized cost on the consolidated balance sheets (see Note 7, “Debt”). The Company measures the fair value of its convertible senior notes for disclosure purposes. The Company estimated the fair value of its convertible senior notes to be $271.7 million and $260.5 million at December 31, 2023 and 2022, respectively, based on Level 2 quoted market prices as of those dates.
Cash Equivalents	Cash Equivalents The Company considers all highly liquid investments with a maturity of three months or less from the date of purchase and that can be liquidated without prior notice or penalty to be cash equivalents.
Short-Term Investments	Short-Term Investments The Company’s short-term investments are classified as available-for-sale securities. Such securities are carried at fair value as determined by prices for identical or similar securities at the balance sheet date. The Company’s short-term investments consist of Level 1 and Level 2 financial instruments in the fair value hierarchy. The net unrealized gains or losses on available-for-sale securities that are not related to credit factors are reported as a component of other comprehensive income (loss) within the statements of operations and accumulated other comprehensive income (loss) as a separate component of stockholders’ equity on the consolidated balance sheets. The Company determines realized gains or losses on the sale of available-for-sale securities using the specific identification method and includes net realized gains and losses as a component of other income or expense within the consolidated statements of operations. The Company reviews its available-for-sale debt securities for credit losses quarterly, considering a variety of factors, including the significance of the decline in value as compared to the amortized cost basis; underlying factors contributing to a decline in the prices of securities in a single asset class; the security’s relative performance versus its peers, sector or asset class; the market and economy in general; views of external investment managers; news or financial information that has been released specific to the investee; and the outlook for the overall industry in which the investee operates. Losses on available-for-sale debt securities as a result of credit factors are recognized by recording an impairment loss as a component of other income or expense within the consolidated statements of operations and a corresponding allowance for credit losses. The Company has not recognized any impairment losses related to its short-term investments during the years ended December 31, 2023, 2022 and 2021.
Concentration of Credit Risk	Concentration of Credit Risk Financial instruments that potentially subject the Company to concentrations of credit risk consist primarily of cash, cash equivalents, short-term investments and accounts receivable. The Company maintains deposit accounts in federally insured financial institutions in excess of federally insured limits. The Company also maintains investments in money market funds that are not federally insured. Additionally, the Company has established guidelines regarding investment instruments and their maturities, which are designed to maintain preservation of principal and liquidity.
Valuation of Inventories	Valuation of Inventories Inventories are valued at the lower of cost or net realizable value, determined by the first-in, first-out method. Inventory is recorded using standard cost, including material, labor and overhead costs. The Company periodically reviews inventories for potential impairment and adjusts inventory for potentially excess or obsolete goods to state inventories at their net realizable value. Factors influencing these adjustments include quantities on hand and firm purchase commitments, expectations of future use, judgments based on quality control testing data and assessments of the likelihood of scrapping or obsoleting certain inventories based on future demand for its products and market conditions.
Long-Lived Assets	Long-Lived Assets Property and Equipment Property and equipment, which primarily consist of office furniture and equipment, manufacturing equipment, scientific equipment, computer equipment, and leasehold improvements, are stated at cost, less accumulated depreciation. Property and equipment are depreciated over the estimated useful lives of the assets, generally three to seven years, using the straight-line method. Leasehold improvements and related equipment are amortized over the lesser of the estimated useful lives of the assets or the remaining lease term, unless there is a transfer of title or purchase option that is reasonably certain to be exercised. Maintenance and repair costs are expensed as incurred.
Operating Lease Right-of-Use Assets and Liabilities	Operating Lease Right-of-Use Assets and Liabilities Operating lease right-of-use assets represent the Company’s right to use an underlying asset for the lease term and lease liabilities represent its obligation to make lease payments arising from the lease. Operating lease right-of-use assets and liabilities are recognized when the Company takes possession of the leased property (Commencement Date) based on the present value of lease payments over the lease term. For lease agreements entered into or reassessed after the adoption of ASC 842 Leases, the Company combines lease and non-lease components. Rent expense on noncancelable leases containing known future scheduled rent increases is recorded on a straight-line basis over the term of the respective leases beginning on the Commencement Date. The difference between rent expense and rent paid is accounted for as a component of operating lease right-of-use assets on the Company’s consolidated balance sheets. Landlord improvement allowances and other similar lease incentives are recorded as a reduction of the right-of-use leased assets, and are amortized on a straight-line basis as a reduction to operating lease costs.
Intangible Assets Subject to Amortization	Intangible Assets Subject to Amortization Finite-lived intangible assets are recorded at cost, net of accumulated amortization and, if applicable, impairment charges. Amortization of finite-lived intangible assets is recognized over their estimated useful lives on a straight-line basis. The Company did not recognize any intangible asset impairment losses during the years ended December 31, 2023, 2022 and 2021.
Impairment of Long-Lived Assets	Impairment of Long-Lived Assets Long-lived assets, such as property and equipment, right-of-use lease assets, and acquired intangible assets subject to amortization, are reviewed for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable. If circumstances require a long-lived asset or asset group be tested for possible impairment, the Company first compares undiscounted cash flows expected to be generated by that asset or asset group to its carrying amount. If the carrying amount of the long-lived asset or asset group is not recoverable on an undiscounted cash flow basis, an impairment is recognized to the extent that the carrying amount exceeds its fair value. Fair value is determined using unobservable (Level 3) inputs, including discounted cash flow models, future estimated sublease income, and third-party independent appraisals, as considered necessary. There is uncertainty in the projected undiscounted future cash flows used in the Company’s impairment review analysis, which requires the use of estimates and assumptions. If actual performance does not achieve the projections, or if the assumptions used change in the future, the Company may be required to recognize additional impairment charges in future periods. Other than the impairment of operating lease right-of-use assets and related leasehold improvements and furniture and fixtures recognized in 2023 and 2022 (see Note 6, “Leases”), there were no impairments of long-lived assets, including acquired intangible assets, during the years ended December 31, 2023, 2022 and 2021.
Strategic Investments	Strategic Investments The Company held equity investments totaling $10.1 million and $16.4 million in two separate private companies at December 31, 2023 and 2022, respectively, each of which represented less than 5% of the outstanding equity of the respective company as of the date of investment. The investments are carried at cost minus impairment, if any, adjusted for changes in observable prices. The Company monitors these investments to evaluate whether any increase or decline in its value has occurred, based on the implied value of recent company financings, public market prices of comparable companies and general market conditions. The investments were included as a component of other long-term assets on the consolidated balance sheets at December 31, 2023 and 2022. In November 2023, the Company made an additional investment of approximately $22.3 million in subordinated convertible notes of one of its private investee companies. The subordinated notes are convertible into equity of the private company upon certain qualifying events, including at their final maturity in 2024. The subordinated convertible notes are non-interest bearing, and are only repayable before conversion into equity upon a change in control of the private company. At December 31, 2023, the $22.3 million subordinated convertible notes investment was included as a component of other long-term assets on the consolidated balance sheet.
Revenue Recognition	Revenue Recognition Revenue is generated primarily from sales of insulin pumps, single-use insulin cartridges and infusion sets to individual customers with third-party insurance coverage and through a network of distributors that resell the products to insulin-dependent diabetes customers. The Company recognizes revenue when it transfers control of the promised goods or services to customers in an amount that reflects the consideration to which the Company expects to be entitled in exchange for those goods or services, net of estimated rebates and returns. Revenue Recognition for Arrangements with Multiple Performance Obligations The Company considers the individual deliverables in its product offering to be separate performance obligations. The transaction price is determined based on the consideration expected to be received, based either on the stated value in contractual arrangements or the estimated cash to be collected in non-contracted arrangements. The Company allocates the consideration to the individual performance obligations and recognizes the consideration based on when the performance obligation is satisfied, considering whether or not this occurs at a point in time or over time. Generally, insulin pumps, cartridges, infusion sets, and accessories are deemed performance obligations that are satisfied at a point in time when the customer obtains control of the promised good, which typically is upon shipment for our distributor arrangements and upon receipt for sales directly to individual customers. Complementary products, such as t:connect, Tandem Source and the Tandem Device Updater, are considered distinct performance obligations that are satisfied over time, as access and support for these products is provided throughout the typical four-year warranty period of the insulin pumps. Accordingly, revenue related to the complementary products is deferred and recognized over a four-year period. Where there is no standalone value for the complementary product, the Company determines its value by applying the expected cost plus a margin approach and then allocates the residual to the insulin pumps. Revenue Recognition for Tandem Choice Program In September 2022, the Company launched a new technology access program referred to as Tandem Choice, that provides eligible, in-warranty t:slim X2 customers in the United States with the flexibility to obtain the newest hardware platform, Tandem Mobi, when it becomes commercially available. Participating customers have the right to purchase the alternative Tandem pump for a fee, referred to as Choice Right. Tandem Choice expires on December 31, 2024. The program was determined to create a material right for which a portion of each t:slim X2 pump transaction price was allocated and deferred. During the third and fourth quarters of 2023, the Company reduced the fee for the Tandem Choice program. The change in the program resulted in an increase to the amount of the transaction price allocated to the material right as the Company expects more customers to exercise the right as compared to the prior existing program price. For purposes of evaluating Tandem Choice in accordance with ASC 606, the Company has determined that the ability for a customer to upgrade to a new technology represents a material right because the pricing inherent in such option provides the customer with a discount that is incremental to the range of discounts that would otherwise be granted for the related goods and services to comparable customers. The standalone selling price for the Choice Right was estimated based on the adjusted market assessment approach and contemplated the likelihood that the respective option will be exercised. Sales Rebates The Company is subject to certain rebates on pricing programs with managed care organizations, such as governmental and third-party commercial payors. The Company estimates provisions for rebates based on contractual arrangements, estimates of products sold subject to rebate, known events or trends and channel inventory data. At December 31, 2023, estimated sales rebates of $8.5 million were recorded on the consolidated balance sheet, of which $8.0 million was included in other long-term liabilities as the estimated payment due date was beyond twelve months from the balance sheet date. Accordingly, actual rebates paid may differ from estimated amounts recorded in the accompanying consolidated financial statements. Shipping and Handling Expenses Shipping and handling expenses associated with product delivery are included within cost of sales in the Company’s statements of operations. Amounts billed to a customer for shipping and handling are reported as revenues.
Warranty Reserve	Warranty Reserve The Company generally provides a four-year warranty on its insulin pumps to end-user customers and may replace any pumps that do not function as intended in accordance with the product specifications within the warranty period. Additionally, the Company offers a six-month warranty on single-use insulin cartridges and infusion sets. Estimated warranty costs are recorded at the time of shipment, and the Company reevaluates the estimate of the warranty reserve obligation at each reporting period. Warranty costs are estimated primarily based on the current expected product replacement cost and expected replacement rates using historical experience. Insulin pumps returned to the Company may be refurbished and redeployed. Experience has shown that initial data for any given pump version or pump platform may be insufficient; therefore, the Company’s process relies on long-term historical averages until sufficient data are available. As actual experience becomes available, the Company uses the data to update the historical averages. The Company may make further adjustments to the warranty reserve when deemed appropriate, giving additional consideration to revised future expectations of performance based on enhanced hardware components, or new features and capabilities that may become available through Tandem Device Updater. Warranty expense is recorded as a component of cost of sales in the consolidated statements of operations.
Stock-Based Compensation	Stock-Based Compensation Stock-based compensation cost is measured at the grant date based on the estimated fair value of the award, and the portion that is ultimately expected to vest is recognized as compensation expense over the requisite service period on a straight-line basis. The Company estimates the fair value of stock options issued under the Company’s stock incentive plans, and the fair value of the employees’ purchase rights under the Company’s Employee Stock Purchase Plan (ESPP), using the Black-Scholes option pricing model on the date of grant. The Black-Scholes option pricing model requires the use of assumptions about a number of variables, including stock price volatility, expected term, dividend yield and risk-free interest rate (see Note 8, “Stockholders’ Equity”). The fair value of restricted stock unit (RSU) awards issued under the Company’s stock incentive plans that vest solely based on service, is estimated based on the fair market value of the underlying stock on the date of grant. The fair value of RSU awards that vest based upon the Company’s actual performance relative to predefined performance metrics, and the awardee’s continuing service through the measurement date, is generally estimated based on the fair market value of the underlying stock on the date of grant and the probability that the specified performance criteria will be met. At each reporting period, the Company reassesses the probability of the achievement of such performance metrics. Any expense change resulting from an adjustment in the estimated shares to be released is recorded in the period of adjustment.
Research and Development Costs	Research and Development Costs All research and development costs are charged to expense as incurred. Such costs include personnel-related costs, including stock-based compensation, supplies, license fees, development prototypes, outside design and testing services, depreciation, allocated facilities and information services, clinical trial costs, milestone payments under the Company’s licensing, development and commercialization agreements, and other indirect costs. Acquired In-Process Research and Development Expenses Acquired in-process research and development (IPR&D) expenses reflect the costs of externally developed IPR&D projects acquired directly in a transaction other than a business combination that do not have an alternative future use, including the initial costs of rights to IPR&D projects. The acquired IPR&D is expensed on acquisition date. Future costs to develop these IPR&D projects are recorded in research and development expenses on the consolidated statements of operations as incurred.
Income Taxes	Income Taxes The Company uses the asset and liability method of accounting for income taxes. Deferred tax assets or liabilities are recognized based on the temporary differences between financial statement and income tax bases of assets and liabilities using enacted tax rates in effect for the years in which the differences are expected to reverse. Tax law and rate changes are reflected in income in the period such changes are enacted. A valuation allowance is recorded when it is more likely than not that some of the deferred tax assets will not be realized. The evaluation of the need for a valuation allowance is performed on a jurisdiction-by-jurisdiction basis, and includes a review of all available positive and negative evidence. Factors reviewed include projections of pre-tax book income for the foreseeable future, determination of cumulative pre-tax book income after permanent differences, earnings history, and reliability of forecasting. The Company will continue to assess the need for a valuation allowance on its deferred tax assets by evaluating both positive and negative evidence that may exist. Any adjustment to the net deferred tax asset valuation allowance would be recorded in the statement of operations for the period that the adjustment is determined to be required. The Company’s income tax returns are based on calculations and assumptions that are subject to examination by the Internal Revenue Service and other tax authorities. In addition, the calculation of the Company’s tax liabilities involves dealing with uncertainties in the application of complex tax regulations. The Company recognizes liabilities for uncertain tax positions using a two-step approach. The first step is to evaluate the tax position for recognition by determining if the weight of available evidence indicates that it is more likely than not that the position will be sustained on audit, including resolution of related appeals or litigation processes, if any. The second step is to measure the tax benefit as the largest amount that is more than 50% likely to be realized upon settlement. While the Company believes it has appropriate support for the positions taken on its tax returns, the Company regularly assesses the potential outcomes of examinations by tax authorities in determining the adequacy of its provision for income taxes. The Company continually assesses the likelihood and amount of potential revisions and adjusts the income tax provision, income taxes payable and deferred taxes in the period in which the facts that give rise to a revision become known. The Company includes interest and penalties related to income taxes, including unrecognized tax benefits, within income tax expense.
Comprehensive Income (Loss)	Comprehensive Income (Loss) All components of comprehensive income (loss), including net income (loss), are reported in the consolidated financial statements in the period in which they are recognized. Comprehensive income (loss) is defined as the change in equity during a period from transactions and other events and circumstances from non-owner sources, including unrealized gains and losses on marketable securities and foreign currency translation adjustments.
Net Income (Loss) Per Share	Net Income (Loss) Per Share Basic net income (loss) per share is calculated by dividing the net income or loss by the weighted average number of common shares outstanding for the period, without consideration for common stock equivalents. Diluted net income (loss) per share reflects the potential dilution that would occur if securities exercisable for or convertible into common stock were exercised for or converted into common stock. Dilutive common share equivalents are comprised of stock options and unvested RSUs outstanding under the Company’s stock incentive plans, potential awards to be granted pursuant to the ESPP, and common stock warrants, each calculated using the treasury stock method; and shares issuable upon conversion of the convertible senior notes calculated using the if-converted method.
Segment Reporting	Segment Reporting Operating segments are identified as components of an enterprise about which discrete financial information is available for evaluation by the chief operating decision-maker (CODM) in making decisions regarding resource allocation and assessing performance. The Company is organized based on its current product portfolio, which consists primarily of insulin pumps, single-use insulin cartridges and infusion sets for the storage and delivery of insulin. The Company views its operations and manages its business as one segment and a single reporting unit because key operating decisions and resource allocations are made by the CODM using consolidated financial data.

Fourth Quarter Financial Data (Unaudited) (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Quarterly Financial Information Disclosure [Abstract]
Sales	$ 196,796	$ 220,502	$ 747,718	$ 801,217	$ 702,799
Gross profit	93,295	115,523	367,690	412,986	376,215
Operating expenses	128,355	133,300	600,920	505,834	353,562
Operating loss	(35,060)	(17,777)	(233,230)	(92,848)	22,653
Net loss	$ (30,002)	$ (15,852)	$ (222,611)	$ (94,594)	$ 15,566
Net loss per share, basic (in dollars per share)	$ (0.46)	$ (0.25)	$ (3.43)	$ (1.47)	$ 0.25
Net loss per share diluted (in dollars per share)	$ (0.46)	$ (0.25)	$ (3.43)	$ (1.47)	$ 0.24
Weighted average shares used to compute basic net loss per share (in shares)	65,369,000	64,384,000	64,969,000	64,146,000	63,000,000
Weighted average shares used to compute diluted net loss per share (in shares)	65,369,000	64,384,000	64,969,000	64,146,000	64,349,000

Employee Benefits	12 Months Ended
Employee Benefits	Dec. 31, 2023
Retirement Benefits [Abstract]
Employee Benefits	Employee Benefits Employee 401(k) Plan The Company has a defined contribution 401(k) plan for employees in the United States who are at least 18 years of age. Employees are eligible to participate in the plan beginning on the first day of the calendar month following their date of hire. Unless they affirmatively elect otherwise, employees are automatically enrolled in the plan following 30 days from date of rehire or entry date. Under the terms of the plan, employees may make voluntary contributions as a percent of compensation and the Company may elect to match a discretionary percentage of employee contributions. The total cost recognized by the Company for the 401(k) plan was $4.2 million and $4.2 million, respectively, for the years ended December 31, 2023 and 2022. The Company did not provide a matching contribution prior to 2022.

Short-Term Investments - Contractual Maturities of Available - For- Sale Debt Securities (Details) $ in Thousands	Dec. 31, 2023 USD ($)
Cash Cash Equivalents And Short Term Investments [Line Items]
Within One Year	$ 246,220
One to Two Years	124,192
Two to Three Years	38,632
Estimated Fair Value	409,044
U.S. Government-sponsored enterprises
Cash Cash Equivalents And Short Term Investments [Line Items]
Within One Year	86,875
One to Two Years	56,647
Two to Three Years	38,632
Estimated Fair Value	182,154
U.S. Treasury securities
Cash Cash Equivalents And Short Term Investments [Line Items]
Within One Year	74,214
One to Two Years	40,790
Two to Three Years	0
Estimated Fair Value	115,004
Commercial paper
Cash Cash Equivalents And Short Term Investments [Line Items]
Within One Year	72,511
One to Two Years	0
Two to Three Years	0
Estimated Fair Value	72,511
Corporate debt securities
Cash Cash Equivalents And Short Term Investments [Line Items]
Within One Year	12,620
One to Two Years	26,755
Two to Three Years	0
Estimated Fair Value	$ 39,375

CONDENSED CONSOLIDATED STATEMENTS OF STOCKHOLDERS’ EQUITY - USD ($)
$ in Thousands

Total

Cumulative Effect, Period of Adoption, Adjustment

^[1]

Common Stock

Additional Paid-in Capital

Cumulative Effect, Period of Adoption, Adjustment

^[1]

Accumulated Other Comprehensive Income (Loss)

Accumulated Deficit

Cumulative Effect, Period of Adoption, Adjustment

^[1]

Beginning balance (in shares) at Dec. 31, 2020

62,335,000

Beginning balance at Dec. 31, 2020

$ 366,305

$ (76,754)

$ 62

$ 1,025,233

$ (85,803)

$ 220

$ (659,210)

$ 9,049

Increase (Decrease) in Stockholders' Equity

Exercise of stock options (in shares)

1,128,791

1,129,000

Exercise of stock options

$ 41,823

$ 2

41,821

Vesting of restricted stock units, net of shares withheld for taxes (in shares)

38,000

Vesting of restricted stock units, net of shares withheld for taxes

(1,551)

Issuance of common stock under Employee Stock Purchase Plan (in shares)

173,000

Issuance of common stock under Employee Stock Purchase Plan

11,069

Exercise of common stock warrants (in shares)

158,000

Exercise of common stock warrants

899

Fair value of common stock warrants at time of exercise

15,500

Stock-based compensation expense

61,091

Unrealized gain (loss) on short-term investments

(693)

Foreign currency translation gain (losses)

(143)

Net income (loss)

15,566

Ending balance (in shares) at Dec. 31, 2021

63,833,000

Ending Balance at Dec. 31, 2021

$ 433,112

$ 64

1,068,259

(616)

(634,595)

Increase (Decrease) in Stockholders' Equity

Exercise of stock options (in shares)

280,275

280,000

Exercise of stock options

$ 9,131

$ 1

9,130

Vesting of restricted stock units, net of shares withheld for taxes (in shares)

131,000

Vesting of restricted stock units, net of shares withheld for taxes

(4,374)

Issuance of common stock under Employee Stock Purchase Plan (in shares)

263,000

Issuance of common stock under Employee Stock Purchase Plan

12,713

Exercise of common stock warrants (in shares)

6,000

Exercise of common stock warrants

Stock-based compensation expense

85,077

Unrealized gain (loss) on short-term investments

(2,233)

Foreign currency translation gain (losses)

1,032

Net income (loss)

(94,594)

Ending balance (in shares) at Dec. 31, 2022

64,513,000

Ending Balance at Dec. 31, 2022

$ 439,947

$ 65

1,170,888

(1,817)

(729,189)

Increase (Decrease) in Stockholders' Equity

Exercise of stock options (in shares)

72,536

73,000

Exercise of stock options

$ 1,295

1,295

Vesting of restricted stock units, net of shares withheld for taxes (in shares)

467,000

Vesting of restricted stock units, net of shares withheld for taxes

(7,790)

Issuance of common stock under Employee Stock Purchase Plan (in shares)

499,000

Issuance of common stock under Employee Stock Purchase Plan

10,679

$ 1

10,678

Stock-based compensation expense

88,926

Unrealized gain (loss) on short-term investments

3,606

Foreign currency translation gain (losses)

(420)

Net income (loss)

(222,611)

Ending balance (in shares) at Dec. 31, 2023

65,552,000

Ending Balance at Dec. 31, 2023

$ 313,632

$ 66

$ 1,263,997

$ 1,369

$ (951,800)

[1]	The Company adopted ASU No. 2020-06, Accounting for Convertible Instruments and Contracts in an Entity’s Own Equity, effective January 1, 2021 (see Note 7, “Debt”).

CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE INCOME (LOSS) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Income Statement [Abstract]
Sales	$ 747,718	$ 801,217	$ 702,799
Cost of sales	380,028	388,231	326,584
Gross profit	367,690	412,986	376,215
Operating expenses:
Selling, general and administrative	352,503	335,681	261,508
Research and development	169,667	139,114	92,054
Acquired in-process research and development expenses	78,750	31,039	0
Total operating expenses	600,920	505,834	353,562
Operating income (loss)	(233,230)	(92,848)	22,653
Other income (expense), net:
Interest income and other, net	22,858	6,057	674
Interest expense	(9,882)	(6,208)	(6,040)
Less: change in fair value of common stock warrants	0	147	(1,386)
Total other income (expense), net	12,976	(4)	(6,752)
Income (loss) before income taxes	(220,254)	(92,852)	15,901
Income tax expense	2,357	1,742	335
Net income (loss)	(222,611)	(94,594)	15,566
Other comprehensive income (loss):
Unrealized gain (loss) on short-term investments	3,606	(2,233)	(693)
Foreign currency translation gains (losses)	(420)	1,032	(143)
Comprehensive income (loss)	$ (219,425)	$ (95,795)	$ 14,730
Net income (loss) per share - basic (in dollars per share)	$ (3.43)	$ (1.47)	$ 0.25
Net income (loss) per share - diluted (in dollars per share)	$ (3.43)	$ (1.47)	$ 0.24
Weighted average shares used to compute basic net income (loss) per share (in shares)	64,969,000	64,146,000	63,000,000
Weighted average shares used to compute diluted net income (loss) per share (in shares)	64,969,000	64,146,000	64,349,000

Debt - Additional Information (Details)		1 Months Ended	3 Months Ended	12 Months Ended
Debt - Additional Information (Details)	Jul. 21, 2022 USD ($)	May 31, 2020 USD ($) trading_day $ / shares	Jun. 30, 2022 USD ($)	Dec. 31, 2023 USD ($)	Dec. 31, 2022 USD ($)	Aug. 02, 2023 USD ($)	Jan. 01, 2021 USD ($)	May 12, 2020 $ / shares
Debt Instrument [Line Items]
Accumulated deficit				$ (951,800,000)	$ (729,189,000)
Convertible senior notes, net - long-term				$ 285,035,000	283,232,000
Cumulative Effect, Period of Adoption, Adjustment \| Accounting Standards Update 2020-06
Debt Instrument [Line Items]
Accumulated deficit							$ 9,000,000
Additional paid in capital							(85,800,000)
Convertible senior notes, net - long-term							$ 76,800,000
Capillary Biomedical
Debt Instrument [Line Items]
Interest rate				5.00%
Long term debt assumed	$ 4,700,000			$ 4,700,000	4,700,000
Line of Credit \| Revolving Credit Facility
Debt Instrument [Line Items]
Debt instrument, term			3 years
Line of credit facility, maximum borrowing capacity			$ 100,000,000			$ 50,000,000
Line of Credit \| Letter of Credit
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity			$ 15,000,000
Convertible senior notes \| Convertible senior notes
Debt Instrument [Line Items]
Principal		$ 287,500,000		287,500,000	287,500,000
Interest rate		1.50%
Net proceeds from issuance of convertible notes		$ 244,600,000
Debt instrument, convertible, conversion ratio		0.0088836
Conversion price (in dollars per share) \| $ / shares		$ 112.57
Debt instrument, convertible, threshold trading days \| trading_day		20
Debt instrument, convertible, threshold trading days consecutive trading days \| trading_day		30
Redemption price percentage		100.00%
Principal amount				0	0
Unamortized debt issuance costs				$ 2,465,000	$ 4,268,000
Effective interest rate				2.20%
Remaining debt term				1 year 3 months 18 days
Additional interest accrual rate		0.50%
Unpaid interest accrual rate		2.50%
Additional interest				$ 3,300,000
Capped call transactions net cost		$ 34,100,000
Debt instrument, initial cap price per share (in dollars per share) \| $ / shares		$ 173.18
Stock price per share (in dollars per share) \| $ / shares								$ 86.59
Convertible senior notes \| Convertible senior notes \| Conversion Instance, 130%
Debt Instrument [Line Items]
Debt instrument, convertible, threshold trading days \| trading_day		20
Debt instrument, convertible, threshold trading days consecutive trading days \| trading_day		30
Convertible senior notes \| Convertible senior notes \| Conversion Instance, 98%
Debt Instrument [Line Items]
Debt instrument, convertible, threshold trading days \| trading_day		5
Debt instrument, convertible, threshold trading days consecutive trading days \| trading_day		5
Convertible senior notes \| Convertible senior notes \| Minimum
Debt Instrument [Line Items]
Conversion price (in dollars per share) \| $ / shares		$ 112.57
Debt instrument, convertible, threshold percentage of stock price trigger		130.00%
Convertible senior notes \| Convertible senior notes \| Minimum \| Conversion Instance, 130%
Debt Instrument [Line Items]
Debt instrument, convertible, threshold percentage of stock price trigger		130.00%
Convertible senior notes \| Convertible senior notes \| Minimum \| Conversion Instance, 98%
Debt Instrument [Line Items]
Debt instrument, convertible, threshold percentage of stock price trigger		98.00%
Convertible senior notes \| Convertible senior notes \| Maximum
Debt Instrument [Line Items]
Conversion price (in dollars per share) \| $ / shares		$ 173.18

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Current assets:
Cash and cash equivalents	$ 58,868	$ 172,517
Short-term investments	409,044	444,384
Accounts receivable, net	105,555	114,717
Inventories	157,937	111,117
Prepaid and other current assets	16,585	7,241
Total current assets	747,989	849,976
Property and equipment, net	76,542	68,552
Operating lease right-of-use assets	87,791	110,626
Other long-term assets	40,336	23,631
Total assets	952,658	1,052,785
Current liabilities:
Accounts payable	49,586	55,730
Accrued expenses	12,726	9,595
Employee-related liabilities	43,430	38,682
Operating lease liabilities	17,060	13,121
Deferred revenue	43,994	18,837
Other current liabilities	28,462	29,325
Total current liabilities	195,258	165,290
Convertible senior notes, net - long-term	285,035	283,232
Operating lease liabilities - long-term	113,572	123,524
Deferred revenue - long-term	13,331	16,874
Other long-term liabilities	31,830	23,918
Total liabilities	639,026	612,838
Commitments and contingencies (Note 13)	0	0
Stockholders’ equity:
Common stock, $0.001 par value; 200,000 shares authorized, 65,552 and 64,513 shares issued and outstanding at December 31, 2023 and 2022, respectively.	66	65
Additional paid-in capital	1,263,997	1,170,888
Accumulated other comprehensive income (loss)	1,369	(1,817)
Accumulated deficit	(951,800)	(729,189)
Total stockholders’ equity	313,632	439,947
Total liabilities and stockholders’ equity	$ 952,658	$ 1,052,785

Leases

12 Months Ended

Dec. 31, 2023

Leases [Abstract]

Leases

The Company's leases consist of operating leases for general office space, research and development, manufacturing and warehouse facilities, and equipment. These noncancellable operating leases have initial lease terms from two years to thirteen years. Leases with an initial term of 12 months or less (Short-term Lease) are expensed as incurred, and are not recorded as right-of-use leased assets and lease liabilities on the Company’s consolidated balance sheets. The Company is required to recognize operating lease right-of-use assets and liabilities, and begin recording lease expense when the Company takes possession of the leased property (Commencement Date). The Company recognizes lease expense for these leases on a straight-line basis over the lease term. Because the Company’s leases do not provide an implicit interest rate, the Company uses its incremental borrowing rate based on the information available at the lease Commencement Date to determine the operating lease right-of-use assets and liabilities based on the present value of future lease payments over the lease term.

Certain leases include an option to renew, with renewal terms that can extend the lease term for additional periods. The exercise of lease renewal options is at the Company’s sole discretion. For renewal options that are reasonably certain at the lease Commencement Date of being exercised, the Company includes the renewal option period in the lease term.

Headquarters Lease

In September 2021, the Company entered into a lease agreement for 181,949 square feet of general administrative, laboratory, and research and development office space (the Premises) located on High Bluff Drive in San Diego, California (Headquarters Lease). Possession of the Premises will be tendered to the Company by the landlord in two phases, with Phase I consisting of 143,850 rentable square feet, and Phase II consisting of 38,099 rentable square feet. The Headquarters Lease also includes a first right of offer with respect to an additional 16,154 rentable square feet of general office space at December 31, 2023, should the space become available.

The Phase I Commencement Date occurred in March 2022 when the Company was tendered possession of the Phase I portion of the Premises, and rent payments commenced in September 2022 (Phase I Rent Commencement Date). The Phase II Commencement Date is expected to occur upon the earlier of (i) the date upon which the Company first commences business in the Phase II portion of the Premises, and (ii) May 1, 2025 (Phase II Rent Commencement Date). The Headquarters Lease term expires in April 2035. The Company has two options to extend the term of the lease, with each option providing for an additional period of five years. The Headquarters Lease term was determined assuming the renewal options would not be exercised.

The initial base rent for the Headquarters Lease is approximately $906,000 per month beginning on the Phase I Rent Commencement Date, and the base rent increases by approximately $255,000 per month on the Phase II Rent Commencement Date. The monthly base rent will increase by 3.0% on each annual anniversary of the respective Rent Commencement Date. In addition to the monthly base rent, the Company is required to pay its proportionate share of certain ongoing operating expenses throughout the duration of the lease. No base rent, other than the proportionate share of operating expenses, will be due for the Phase I portion of the Premises for months two through nine following the Phase I Rent Commencement Date, and for the Phase II portion of the Premises for months two through five following the Phase II Rent Commencement Date. The Company recognized operating lease right-of-use assets and corresponding operating lease liabilities of $107.5 million on the consolidated balance sheet on the Phase I Commencement Date in the first quarter of 2022.

In December 2023, the Company entered into an agreement to sublease the Phase II portion of the Premises under its Headquarters Lease from January 2025 through March 2029. Future minimum payments for base rent due under Phase II of the Headquarters Lease, net of sublease rent, are estimated to be $2.2 million in total for 2025 through 2028, and $23.2 million in total for 2029 through 2035.

Operating Lease Termination and Impairment Charges

In the second quarter of 2023, the Company began using Phase I of the Headquarters Lease for operations that previously occupied 77,458 square feet of leased space located on Roselle Street (Roselle leases) in San Diego, California. The Roselle leases expired in May 2023. Also in the second quarter of 2023, the Company relocated operations that occupied 73,929 square feet of leased space on Vista Sorrento Parkway in San Diego, California (Vista Sorrento Lease) to the new Headquarters Lease location.

During the second quarter of 2023, in connection with permanently ceasing use of the Vista Sorrento facility, the Company recorded a $14.1 million impairment charge as the carrying amount of the assets related to the Vista Sorrento Lease exceeded its fair value based on the Company’s estimate of future discounted cash flows related to the leased facility. Estimates used to determine the present value of future cash flows over the remaining lease term included projected sublease income and a discount rate. The $14.1 million charge was comprised of an $11.2 million impairment of operating lease right-of-use assets and a $2.9 million write-off of fixed assets consisting primarily of leasehold improvements, and was recorded as a component of selling, general and administrative expenses in the consolidated statement of operations.

During the fourth quarter of 2022, the Company recorded $12.4 million of lease termination and impairment charges primarily related to its customer and technical support office space in Boise, Idaho. The $12.4 million charge consisted of a $6.7 million loss on disposal of fixed assets, including leasehold improvements, furniture and fixtures, $3.8 million net loss on lease termination, and $1.9 million impairment of operating lease right-of-use assets, and was recorded as a component of selling, general and administrative expenses in the consolidated statement of operations.

Lease Costs

The Company’s lease costs recorded in the consolidated statements of operations were as follows (in thousands):


	Year Ended December 31,
		2023		2022		2021
Operating lease cost		$	15,971	$	18,432	$	8,627
Short-term lease cost		108		142		90
Loss on lease termination and right-of-use asset impairment charges		11,224		5,699		—
Total lease cost		$	27,303	$	24,273	$	8,717

Lease Liabilities

Maturities of operating lease liabilities at December 31, 2023 were as follows (in thousands):


Years Ending December 31,
2024	$	17,065
2025	17,023
2026	17,068
2027	17,333
2028	13,840
Thereafter	90,004
Total undiscounted lease payments	172,333
Less: amount representing interest	(41,701)
Present value of operating lease liabilities	130,632
Less: current portion of operating lease liabilities	(17,060)
Operating lease liabilities - long-term	$	113,572

The weighted-average remaining lease term and weighted-average discount rate for operating leases were as follows:


	December 31, 2023		December 31, 2022
Weighted-average remaining lease term (in years)	10.2		10.8
Weighted-average discount rate used to determine operating lease liabilities	5.4	%	5.3	%

Lease Payments

Cash paid for amounts included in the measurement of lease liabilities, representing operating cash flows, were as follows (in thousands):


	Year Ended December 31,
	2023		2022		2021
Operating lease payments	$	13,864	$	11,960	$	9,462
Operating lease termination payments	—		4,769		—
Total cash payments	$	13,864	$	16,729	$	9,462

Leases For Which Accounting Has Not Yet Commenced

As of December 31, 2023, the Phase II Commencement Date for the Headquarters Lease had not yet occurred. Accordingly, the consolidated balance sheet at December 31, 2023 does not include operating lease right-of-use assets and operating lease liabilities, and the consolidated statements of operations for the years ended December 31, 2023, 2022 and 2021 do not include any lease costs, related to Phase II of the Headquarters Lease. In addition, the above disclosures of the Company’s lease costs, maturities of operating lease liabilities, weighted-average remaining lease term, and weighted-average discount rate do not include any amounts related to Phase II of the Headquarters Lease. Because the incremental borrowing rate will not be available until the Phase II Commencement Date, which is currently estimated to occur in the first quarter of 2025, we are not yet able to determine the Phase II operating lease right-of-use assets and liabilities.

Fourth Quarter Financial Data (Unaudited)

12 Months Ended

Dec. 31, 2023

Quarterly Financial Information Disclosure [Abstract]

Fourth Quarter Financial Data (Unaudited)

The financial information for the three months ended December 31, 2023 and 2022 presented in the following table reflects all normal recurring adjustments that are, in the opinion of management, necessary for a fair statement of the results of the interim periods (in thousands, except per share data):


	For the Quarter Ended
	December 31, 2023		December 31, 2022
Sales	$	196,796	$	220,502
Gross profit	$	93,295	$	115,523
Operating expenses	$	128,355	$	133,300
Operating loss	$	(35,060)	$	(17,777)
Net loss	$	(30,002)	$	(15,852)
Net loss per share, basic and diluted	$	(0.46)	$	(0.25)
Weighted average shares used to compute basic and diluted net loss per share	65,369		64,384

For the three months ended December 31, 2023 and 2022, there was no difference in the weighted average number of shares used to calculate basic and diluted net loss per share due to the Company’s net loss position for each of the periods presented.

Income Taxes - Schedule of Components of Income Tax (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Current:
Federal	$ 308	$ 216	$ 0
State	345	1,228	174
Foreign	1,704	298	161
Total current tax expense	2,357	1,742	335
Deferred:
Federal	0	0	0
State	0	0	0
Foreign	0	0	0
Total deferred income tax benefit	0	0	0
Income tax expense	$ 2,357	$ 1,742	$ 335

Cover Page - USD ($) $ in Billions	12 Months Ended
Cover Page - USD ($) $ in Billions	Dec. 31, 2023	Feb. 16, 2024	Jun. 30, 2023
Cover [Abstract]
Document Type	10-K
Document Annual Report	true
Document Period End Date	Dec. 31, 2023
Current Fiscal Year End Date	--12-31
Document Transition Report	false
Entity File Number	001-36189
Entity Registrant Name	Tandem Diabetes Care, Inc.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	20-4327508
Entity Address, Address Line One	12400 High Bluff Drive
Entity Address, City or Town	San Diego
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	92130
City Area Code	858
Local Phone Number	366-6900
Title of 12(b) Security	Common Stock, par value $0.001 per share
Trading Symbol	TNDM
Security Exchange Name	NASDAQ
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
ICFR Auditor Attestation Flag	true
Document Financial Statement Error Correction [Flag]	false
Entity Shell Company	false
Entity Public Float			$ 1.6
Entity Common Stock, Shares Outstanding (in shares)		65,631,041
Documents Incorporated by Reference	Portions of the registrant’s definitive Proxy Statement on Schedule 14A for the 2024 Annual Meeting of Stockholders to be filed with the Securities and Exchange Commission not later than 120 days after the end of the fiscal year covered by this Form 10-K, are incorporated by reference in Part III, Items 10-14 of this Form 10-K.
Amendment Flag	false
Document Fiscal Year Focus	2023
Document Fiscal Period Focus	FY
Entity Central Index Key	0001438133

Stockholders' Equity - Assumptions Used in Black-Scholes Option-Pricing Model (Details) - $ / shares	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Share-based Payment Arrangement, Option
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average grant date fair value - options (in dollars per share)		$ 42.16	$ 56.89
Risk-free interest rate		2.70%	1.00%
Dividend yield		0.00%	0.00%
Expected volatility		72.00%	75.10%
Expected term (in years)		5 years 9 months 18 days	6 years 1 month 6 days
Awards to be granted under the ESPP
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average grant date fair value (in dollars per share)	$ 10.35	$ 21.89	$ 38.19
Risk-free interest rate	4.90%	3.40%	0.20%
Dividend yield	0.00%	0.00%	0.00%
Expected volatility	63.90%	56.90%	44.20%
Expected term (in years)	1 year 3 months 18 days	1 year 3 months 18 days	1 year 3 months 18 days

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

+ Details

Income Taxes - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Operating Loss Carryforwards [Line Items]
Valuation allowance	$ 190,664,000	$ 162,726,000
Net deferred tax assets	0	0
Unrecognized tax benefits	19,200,000	15,000,000
Accrual interest and penalties	0	0	$ 0
Capillary Biomedical
Operating Loss Carryforwards [Line Items]
Deferred tax assets acquired		$ 7,800,000
Net deferred tax assets	$ 5,000,000
Minimum
Operating Loss Carryforwards [Line Items]
Income tax realization	50.00%
California
Operating Loss Carryforwards [Line Items]
NOL carryforwards subject to expiration	$ 177,600,000
Federal
Operating Loss Carryforwards [Line Items]
NOL carry forwards amount	168,000,000.0
NOL carryforwards not subject to expiration	78,400,000
NOL carryforwards subject to expiration	89,600,000
Federal \| Research Tax Credit Carryforward
Operating Loss Carryforwards [Line Items]
Tax credit carryforward, amount	24,200,000
State and Local
Operating Loss Carryforwards [Line Items]
NOL carry forwards amount	262,400,000
California \| Research Tax Credit Carryforward
Operating Loss Carryforwards [Line Items]
Tax credit carryforward, amount	24,200,000
Foreign
Operating Loss Carryforwards [Line Items]
NOL carryforwards subject to expiration	$ 19,900,000

Composition of Certain Financial Statement Items - Reconciliation of Change in Estimated Allowance for Doubtful Accounts (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Allowance for doubtful accounts
Balance at beginning of the period	$ 4,327	$ 4,249	$ 3,857
Provision for expected credit losses	5,540	4,782	2,333
Write-offs and adjustments, net of recoveries	(4,969)	(4,704)	(1,941)
Balance at end of the period	$ 4,898	$ 4,327	$ 4,249

Stockholders' Equity (Tables)

12 Months Ended

Dec. 31, 2023

Equity [Abstract]

Schedule of Shares of Common Stock Reserved for Future Issuance

The following shares of the Company's common stock were reserved for future issuance at December 31, 2023 (in thousands):


Shares reserved for issuance upon conversion of Convertible Senior Notes			2,554
Shares underlying outstanding warrants			194
Shares underlying outstanding stock options			3,896
Shares underlying unvested restricted stock units			3,176
Shares authorized for issuance pursuant to awards granted under the ESPP			454
Shares authorized for future equity award grants			702
Total			10,976

Schedule of Stockholders' Equity Common Stock Warrants

Warrants outstanding to purchase shares of the Company's common stock as of December 31, 2023 were as follows:

Issue Date

Exercise Price Per Share

Warrants Outstanding

Expiration Date of Warrants Outstanding

March 2017

$23.50

193,788

March 2027

Schedule of Stock Option Activities for 2006 Plan and 2013 Plan

The following table summarizes stock option activities under the Company’s stock incentive plans:


	Total Stock Options	Weighted- Average Exercise Price Per Share		Weighted- Average Remaining Contractual Life (in years)	Aggregate Intrinsic Value (in thousands)
Outstanding at December 31, 2020	5,803,505	$	52.08	7.90	$	268,649
Granted	355,008	$	86.68
Exercised	(1,128,791)	$	37.05		$	86,149
Canceled/forfeited/expired	(214,876)	$	76.29		$	6,963
Outstanding at December 31, 2021	4,814,846	$	57.08	7.07	$	452,081
Granted	83,008	$	65.28
Exercised	(280,275)	$	32.58		$	13,473
Canceled/forfeited/expired	(175,266)	$	77.93		$	2,143
Outstanding at December 31, 2022	4,442,313	$	57.95	6.12	$	30,236
Granted	—	$	—
Exercised	(72,536)	$	17.86		$	1,400
Canceled/forfeited/expired	(473,773)	$	90.14		$	95
Outstanding at December 31, 2023	3,896,004	$	54.79	5.30	$	11,703
Vested and expected to vest at December 31, 2023	3,890,496	$	54.75	5.30	$	11,703
Exercisable at December 31, 2023	3,675,678	$	53.11	5.19	$	11,703

Schedule of Restricted Stock Units

The following table summarizes RSU activities, which includes performance-based RSUs, for the Company’s stock incentive plans:


	Total RSUs	Weighted-Average Grant Date Fair Value		Aggregate Intrinsic Value (in thousands)
Unvested awards outstanding at December 31, 2020	132,802	$	82.82	$	12,706
Granted	564,034	$	96.37
Vested	(53,957)	$	82.74
Canceled/forfeited	(32,148)	$	87.21
Unvested awards outstanding at December 31, 2021	610,731	$	95.08	$	91,927
Granted	1,542,859	$	67.09
Vested	(202,215)	$	91.99
Canceled/forfeited	(117,543)	$	84.20
Unvested awards outstanding at December 31, 2022	1,833,832	$	72.57	$	82,431
Granted	2,359,907	$	28.13
Vested	(735,155)	$	73.17
Canceled/forfeited	(282,425)	$	59.17
Unvested awards outstanding at December 31, 2023	3,176,159	$	40.61	$	93,951
Awards expected to vest at December 31, 2023	3,088,745	$	40.50	$	91,365

Schedule of Assumptions Used in Black-Scholes Option-Pricing Model

The Company estimates the fair value of stock options using the Black-Scholes option pricing model on the grant date. The assumptions used in the Black-Scholes option pricing model were as follows:


		Stock Options
	Year Ended December 31,
		2023	2022			2021
Weighted average grant date fair value (per share)		N/A	$	42.16		$	56.89
Risk-free interest rate		N/A	2.7		%	1.0		%
Dividend yield		N/A	0.0		%	0.0		%
Expected volatility		N/A	72.0		%	75.1		%
Expected term (in years)		N/A	5.8			6.1

Schedule of Share-Based Payment Award, Employee Stock Purchase Plan, Valuation Assumptions

The assumptions used in the Black-Scholes option pricing model for the ESPP were as follows:


					ESPP
	Year Ended December 31,
		2023			2022			2021
Weighted average grant date fair value (per share)		$	10.35		$	21.89		$	38.19
Risk-free interest rate		4.9		%	3.4		%	0.2		%
Dividend yield		0.0		%	0.0		%	0.0		%
Expected volatility		63.9		%	56.9		%	44.2		%
Expected term (in years)		1.3			1.3			1.3

Schedule of Compensation Cost Included in Consolidated Statement of Operations

The following table summarizes the allocation of stock-based compensation expense included in the consolidated statements of operations for all stock-based compensation arrangements (in thousands):


	Year Ended December 31,
		2023		2022		2021
Cost of sales		$	6,212	$	7,685	$	6,434
Selling, general and administrative		56,304		57,196		43,567
Research and development		25,561		20,037		10,751
Total stock-based compensation expense		$	88,077	$	84,918	$	60,752

Summary of Significant Accounting Policies - Anti-Dilutive Securities (Details) - shares shares in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share, amount (in shares)	4,986	5,012	5,679
Options to purchase common stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share, amount (in shares)	135	1,138	3,124
Unvested restricted stock units
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share, amount (in shares)	2,089	1,118	0
Warrants to purchase common stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share, amount (in shares)	194	194	1
Awards granted under the ESPP
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share, amount (in shares)	14	8	0
Convertible senior notes (if-converted)
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share, amount (in shares)	2,554	2,554	2,554

Composition of Certain Financial Statement Items - Summary of Property and Equipment (Detail) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Property, Plant and Equipment [Line Items]
Total cost	$ 129,336	$ 124,727
Less: accumulated depreciation and amortization	(52,794)	(56,175)
Total property and equipment, net	76,542	68,552
Leasehold improvements
Property, Plant and Equipment [Line Items]
Total cost	37,565	35,828
Office furniture and equipment
Property, Plant and Equipment [Line Items]
Total cost	11,842	13,772
Computer equipment and software
Property, Plant and Equipment [Line Items]
Total cost	10,340	12,330
Manufacturing and scientific equipment
Property, Plant and Equipment [Line Items]
Total cost	$ 69,589	$ 62,797

Organization and Basis of Presentation (Details)	12 Months Ended
Organization and Basis of Presentation (Details)	Dec. 31, 2023
Insulin Pump \| Minimum
Organization And Basis Of Presentation [Line Items]
Expected life span term	4 years

Composition of Certain Financial Statement Items - Intangible Assets Subject to Amortization (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Intangible assets, gross amount	$ 12,502	$ 12,502
Accumulated amortization	(9,726)	(7,875)
Intangible assets, net	$ 2,776	$ 4,627
Weighted average remaining amortization period (in months)	18 months	30 months

Stockholders' Equity - Additional Information (Details) $ in Millions	1 Months Ended			3 Months Ended		12 Months Ended
	Mar. 31, 2022	Feb. 28, 2022	Oct. 31, 2013	Jun. 30, 2022	Mar. 31, 2022	Dec. 31, 2023 USD ($) purchase_period shares	Dec. 31, 2022 USD ($) shares	Dec. 31, 2021 USD ($) shares	May 31, 2023 shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares issued by each warrant (in shares)						1
Common stock reserved for future issuance (in shares)						10,976,000			2,602,184
Total stock-based compensation expense capitalized as part of cost of inventory \| $						$ 2.0	$ 1.1
Unrecognized compensation expense \| $						$ 116.7
Share-based payment arrangement, cost not yet recognized, period for recognition						1 year 10 months 24 days
Share-based Payment Arrangement, Option
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Maximum term of stock options (in years)						10 years
Vesting period				3 years	4 years
Vesting period of remaining stock (in years)				2 years	3 years
Share-based Payment Arrangement, Option \| Tranche One
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock vested percentage				33.00%	25.00%
Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	3 years	4 years
Granted (in shares)						2,359,907	1,542,859	564,034
RSU vested in period, fair value \| $						$ 21.2	$ 12.7	$ 5.1
Restricted Stock Units (RSUs) \| Tranche One
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock vested percentage	33.00%	25.00%
Restricted Stock Units (RSUs) \| Tranche Two
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	2 years	3 years
Performance-Based Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted (in shares)						110,074	53,662	25,674
Awards to be granted under the ESPP
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period						2 years
Maximum percentage that employee can contribute for purchase of common stock			15.00%
Offering period						2 years
Number of purchase periods \| purchase_period						4
Purchase period						6 months
Purchase of common stock under ESPP (in shares)						499,431	262,936	172,694
Proceeds from stock plans \| $						$ 10.7	$ 12.7	$ 11.1
Date of Offering \| Awards to be granted under the ESPP
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Purchase price of common stock on date of purchase			85.00%
Date of Purchase \| Awards to be granted under the ESPP
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Purchase price of common stock on date of purchase			85.00%

Income Taxes

12 Months Ended

Dec. 31, 2023

Income Tax Disclosure [Abstract]

Income Taxes

The income (loss) before provision for income taxes for the Company’s operations was as follows (in thousands):


	Year Ended December 31,
	2023		2022		2021
United States	$	(135,411)	$	(94,033)	$	15,211
Foreign	(84,843)		1,181		690
Income (loss) before provision for income taxes	$	(220,254)	$	(92,852)	$	15,901

The components of income tax expense were as follows (in thousands):


	Year Ended December 31,
	2023		2022		2021
Current:
Federal	$	308	$	216	$	—
State	345		1,228		174
Foreign	1,704		298		161
Total current tax expense	2,357		1,742		335
Deferred:
Federal	—		—		—
State	—		—		—
Foreign	—		—		—
Total deferred income tax benefit	—		—		—
Income tax expense	$	2,357	$	1,742	$	335

The expense for income taxes reconciles to the amount computed by applying the federal statutory rate to loss before taxes as follows (in thousands):


	Year Ended December 31,
	2023		2022		2021
Income tax expense (benefit) at federal statutory rate (1)	$	(46,253)	$	(19,499)	$	3,339
State income tax, net of federal benefit	(1,313)		(926)		(254)
Warrants revaluation	—		(31)		356
Research and development credits	(6,283)		(6,263)		(5,703)
Section 382 limitation	(5)		—		(97)
Stock-based compensation	14,904		2,282		(7,609)
Officers' compensation	1,547		2,931		4,024
Recognition of acquired deferred tax assets	(5,048)		—		—
Acquired IPR&D expenses	14,938		6,518		—
Other	1,074		962		124
Change in valuation allowance	28,796		15,768		6,155
Income tax expense	$	2,357	$	1,742	$	335

(1)For the years ended December 31, 2023, 2022 and 2021, the federal statutory tax rate was 21%.

Significant components of the Company’s net deferred income tax assets at December 31, 2023 and 2022 are shown in the table below (in thousands). The Company assesses all available positive and negative evidence to estimate whether sufficient future taxable income will be generated to permit use of the existing deferred tax assets. A significant piece of objective negative evidence evaluated was the cumulative book loss incurred over the three-year period ended December 31, 2023. Such objective evidence limits the ability to consider other subjective evidence, such as projections for future growth. On the basis of this analysis, a valuation allowance of $190.7 million and $162.7 million at December 31, 2023 and 2022, respectively, was recorded to offset the net deferred tax asset as realization of such asset is uncertain. However, the amount of the deferred tax asset considered realizable could be adjusted if estimates of future taxable income during the carryforward period are increased, or if objective negative evidence in the form of cumulative losses is no longer present and additional weight is given to subjective evidence such as the Company’s projections for future growth.


	December 31,
	2023		2022
Deferred tax assets:
Net operating loss (NOL) carryforwards	$	54,802	$	54,598
Research and development tax credits carryforwards	27,516		22,400
Capitalized research and development expenses	52,875		29,760
Accrued compensation	32,097		34,378
Lease liabilities	31,037		32,738
Other	20,778		20,927
Total deferred tax assets	219,105		194,801
Deferred tax liabilities:
Operating lease right-of-use assets	(20,869)		(26,505)
Fixed assets	(6,916)		(4,467)
Other	(656)		(1,103)
Total deferred tax liabilities	(28,441)		(32,075)
Less valuation allowance	(190,664)		(162,726)
Net deferred tax assets	$	—	$	—

As of December 31, 2023, the Company had accumulated federal and state NOL carryforwards of approximately $168.0 million, and $262.4 million, respectively. Of the total federal net operating loss carryforwards, approximately $78.4 million were generated after January 1, 2018, and therefore do not expire. NOL generated after January 1, 2018, is subject to 80% limitation in accordance with the Tax Cuts and Jobs Act of 2017. The remaining federal net operating loss carryforwards of $89.6 million will begin to expire in 2033, and state tax loss carryforwards continue to expire in 2024, unless previously utilized. The remaining California NOL carryforwards of $177.6 million will begin expiring in 2031. The Company had approximately $19.9 million of foreign tax loss carryforwards as of December 31, 2023. The foreign tax loss carryforwards begin to expire in 2024, unless previously utilized.

The Company also has federal and California research credit carryforwards of approximately $24.2 million and $24.2 million, respectively, as of December 31, 2023. The federal research credit carryforwards will begin expiring in 2039, unless previously utilized. The California research credit will carry forward indefinitely.

Utilization of the Company's net operating loss and research credit carryforwards may be subject to a substantial annual limitation due to ownership change limitations provided by Section 382 of the Internal Revenue Code of 1986, as amended, and similar state provisions. The annual limitations may result in the expiration of net operating loss carryforwards before utilization. The Company has completed analyses through December 31, 2022 to determine whether its net operating losses and credits are likely to be limited by Section 382. Based on this study, the Company determined that an ownership change, as defined under Section 382, occurred in 2018 and the resulting limitation significantly reduced the Company’s ability to utilize its net operating loss and credit carryovers before they expire. As a result, in 2019 the Company reduced its deferred tax assets for the net operating loss and research credit carryforwards that were projected to expire unused with a corresponding offset to the valuation allowance recorded against such assets. Additionally, future ownership changes under Section 382 may also limit the Company's ability to fully utilize any remaining tax benefits.

In 2022, as part of the Capillary Biomedical, Inc. transaction, the Company acquired deferred tax assets consisting of federal and state net operation loss carryovers, research tax credit carryovers, and other tax attributes of approximately $7.8 million. These deferred tax assets are subject to limitations on future use under Section 382 and some of the attributes may expire unused. The Company completed an analysis under Section 382. As a result, the Company recognized deferred tax assets, net of contra reserve, of approximately $5.0 million in 2023. The Company included these deferred tax assets in its components of deferred tax assets in the table above, to the extent that such deferred tax assets are available for future utilization, and the balances are fully offset by valuation allowance as of December 31, 2023.

The evaluation of uncertainty in a tax position is a two-step process. The first step involves recognition. The Company determines whether it is more likely than not that a tax position will be sustained upon tax examination, including resolution of any related appeals or litigation, based on only the technical merits of the position. The technical merits of a tax position are derived from both statutory and judicial authority (legislation and statutes, legislative intent, regulations, rulings, and case law) and their applicability to the facts and circumstances of the tax position. If a tax position does not meet the more-likely-than-not recognition threshold, the benefit of that position is not recognized in the financial statements. The second step is measurement. A tax position that meets the more-likely-than-not recognition threshold is measured to determine the amount of benefit to recognize in the financial statements. The tax position is measured as the largest amount of benefit that is greater than 50% likely of being realized upon ultimate resolution with a taxing authority.

The following table summarizes the activity related to the Company’s gross unrecognized tax benefits at the beginning and end of the years ended December 31, 2023, 2022 and 2021 (in thousands):


	Year Ended December 31,
	2023		2022		2021
Gross unrecognized tax benefits at the beginning of the year	$	16,986	$	13,589	$	10,107
Increases related to current year positions	3,961		3,403		3,482
Increases (decreases) related to prior year positions	580		(6)		—
Gross unrecognized tax benefits at the end of the year	$	21,527	$	16,986	$	13,589

As of December 31, 2023 and December 31, 2022, the Company had $19.2 million and $15.0 million of unrecognized tax benefits, respectively, that, if recognized and realized would impact the effective tax rate, subject to the valuation allowance.

The Company’s practice is to recognize interest and penalties related to income tax matters in income tax expense. The Company had no accrual for interest and penalties on the Company’s consolidated balance sheets and has not recognized interest and penalties in the consolidated statements of operations for the years ended December 31, 2023, 2022 and 2021. The Company does not expect any significant increases or decreases, other than the potential reduction as a result of the Section 382 limitation, to its unrecognized tax benefits within the next 12 months.

The Company is subject to taxation in the United States and various foreign and state jurisdictions. Before 2018, the losses were all attributable to the United States. The Company’s tax years from 2006 (inception) are subject to examination by the United States and state authorities due to the carry forward of unutilized NOLs and research and development credits.

- Definition

The entire disclosure for income taxes. Disclosures may include net deferred tax liability or asset recognized in an enterprise's statement of financial position, net change during the year in the total valuation allowance, approximate tax effect of each type of temporary difference and carryforward that gives rise to a significant portion of deferred tax liabilities and deferred tax assets, utilization of a tax carryback, and tax uncertainties information.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480990/946-20-50-13

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 235
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-Name Accounting Standards Codification
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-Paragraph 1
-Subparagraph (SX 210.4-08(h)(2))
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Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-Name Accounting Standards Codification
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Reference 4: http://www.xbrl.org/2003/role/disclosureRef
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-Name Accounting Standards Codification
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Reference 5: http://www.xbrl.org/2003/role/disclosureRef
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Reference 6: http://www.xbrl.org/2003/role/disclosureRef
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Reference 7: http://www.xbrl.org/2003/role/disclosureRef
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Reference 10: http://www.xbrl.org/2003/role/disclosureRef
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-Paragraph 2
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482603/740-30-50-2

+ Details

Income Taxes (Tables)

12 Months Ended

Dec. 31, 2023

Income Tax Disclosure [Abstract]

Schedule of Income (Loss) Before Provision for Income Taxes

The income (loss) before provision for income taxes for the Company’s operations was as follows (in thousands):


	Year Ended December 31,
	2023		2022		2021
United States	$	(135,411)	$	(94,033)	$	15,211
Foreign	(84,843)		1,181		690
Income (loss) before provision for income taxes	$	(220,254)	$	(92,852)	$	15,901

Schedule of Components of Income Tax Expense

The components of income tax expense were as follows (in thousands):


	Year Ended December 31,
	2023		2022		2021
Current:
Federal	$	308	$	216	$	—
State	345		1,228		174
Foreign	1,704		298		161
Total current tax expense	2,357		1,742		335
Deferred:
Federal	—		—		—
State	—		—		—
Foreign	—		—		—
Total deferred income tax benefit	—		—		—
Income tax expense	$	2,357	$	1,742	$	335

Schedule of Effective Income Tax Rate Reconciliation

The expense for income taxes reconciles to the amount computed by applying the federal statutory rate to loss before taxes as follows (in thousands):


	Year Ended December 31,
	2023		2022		2021
Income tax expense (benefit) at federal statutory rate (1)	$	(46,253)	$	(19,499)	$	3,339
State income tax, net of federal benefit	(1,313)		(926)		(254)
Warrants revaluation	—		(31)		356
Research and development credits	(6,283)		(6,263)		(5,703)
Section 382 limitation	(5)		—		(97)
Stock-based compensation	14,904		2,282		(7,609)
Officers' compensation	1,547		2,931		4,024
Recognition of acquired deferred tax assets	(5,048)		—		—
Acquired IPR&D expenses	14,938		6,518		—
Other	1,074		962		124
Change in valuation allowance	28,796		15,768		6,155
Income tax expense	$	2,357	$	1,742	$	335

(1)For the years ended December 31, 2023, 2022 and 2021, the federal statutory tax rate was 21%.

Schedule of Deferred Tax Assets and Liabilities


	December 31,
	2023		2022
Deferred tax assets:
Net operating loss (NOL) carryforwards	$	54,802	$	54,598
Research and development tax credits carryforwards	27,516		22,400
Capitalized research and development expenses	52,875		29,760
Accrued compensation	32,097		34,378
Lease liabilities	31,037		32,738
Other	20,778		20,927
Total deferred tax assets	219,105		194,801
Deferred tax liabilities:
Operating lease right-of-use assets	(20,869)		(26,505)
Fixed assets	(6,916)		(4,467)
Other	(656)		(1,103)
Total deferred tax liabilities	(28,441)		(32,075)
Less valuation allowance	(190,664)		(162,726)
Net deferred tax assets	$	—	$	—

Schedule of Unrecognized Tax Benefits

The following table summarizes the activity related to the Company’s gross unrecognized tax benefits at the beginning and end of the years ended December 31, 2023, 2022 and 2021 (in thousands):


	Year Ended December 31,
	2023		2022		2021
Gross unrecognized tax benefits at the beginning of the year	$	16,986	$	13,589	$	10,107
Increases related to current year positions	3,961		3,403		3,482
Increases (decreases) related to prior year positions	580		(6)		—
Gross unrecognized tax benefits at the end of the year	$	21,527	$	16,986	$	13,589

Debt - Interest Expense Recognized (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Debt Instrument [Line Items]
Amortization of debt issuance costs	$ 2,204	$ 1,896	$ 1,727
Convertible senior notes \| Convertible senior notes
Debt Instrument [Line Items]
Contractual interest expense	7,565	4,313	4,313
Amortization of debt issuance costs	1,803	1,896	1,727
Total interest expense	9,368	$ 6,209	$ 6,040
Additional interest	$ 3,300

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

+ Details

Debt

12 Months Ended

Dec. 31, 2023

Debt Disclosure [Abstract]

Debt

Convertible Senior Notes

In May 2020, the Company completed an offering of $287.5 million aggregate principal amount of unsecured Convertible Senior Notes with a stated interest rate of 1.50% and a maturity date of May 1, 2025 (Notes). The proceeds from the issuance of the Notes were $244.6 million, net of debt issuance costs and cash used to pay the cost of the capped call transactions (Capped Call Transactions) discussed below.

Interest is payable in cash semi-annually in arrears beginning on November 1, 2020 at a rate of 1.50% per year. The Notes mature on May 1, 2025 unless repurchased, redeemed, or converted in accordance with their terms before the maturity date.

The Notes are convertible into cash, shares of the Company’s common stock, or a combination of cash and shares of the Company’s common stock, at the Company’s election, at an initial conversion rate of 8.8836 shares of common stock per $1,000 principal amount of the Notes, which is equivalent to an initial conversion price of $112.57 (Conversion Price) per share of the Company’s common stock. The conversion rate is subject to customary adjustments for certain events as described in the Indenture governing the Notes.

The Company has the option to redeem for cash all or any portion of the Notes on or after May 6, 2023 if the last reported sale price of the Company’s common stock has been at least 130% of the Conversion Price then in effect for at least 20 trading days (whether or not consecutive), including the trading day immediately preceding the date on which the Company provides notice of redemption, during any 30 consecutive trading day period, at a redemption price equal to 100% of the principal amount of the Notes to be redeemed, plus accrued and unpaid interest. No sinking fund is provided for the Notes.

Holders of the Notes may convert all or a portion of their Notes at their option before November 1, 2024, in multiples of $1,000 principal amounts, only under the following circumstances:

•if the last reported sale price of the Company’s common stock for at least 20 trading days (whether or not consecutive) during the period of 30 consecutive trading days ending on the last trading day of the immediately preceding calendar quarter is greater than or equal to 130% of the applicable conversion price of the Notes on each such trading day;

•during the five business day period after any five consecutive trading day period in which the trading price per $1,000 principal amount of the Notes for each day of that five consecutive trading day period was less than 98% of the product of the last reported sale price of the Company’s common stock and the applicable conversion rate of the Notes on such trading day;

•if the Company calls any or all of the Notes for redemption, at any time before the close of business on the scheduled trading day immediately preceding the redemption date; or

•on the occurrence of specified corporate events.

On or after November 1, 2024, until the close of business on the second scheduled trading day immediately preceding the maturity date, holders may convert their Notes at any time, regardless of the foregoing circumstances.

Holders of the Notes who convert in connection with a make-whole fundamental change or in connection with a redemption are entitled to an increase in the conversion rate. Additionally, in the event of a fundamental change, holders of the Notes may require us to repurchase all or a portion of the Notes at a price equal to 100% of the principal amount of the Notes, plus any accrued and unpaid interest.

In accounting for the issuance of the Notes in 2020, the Company separated the Notes into liability and equity components. The carrying amount of the liability component was calculated by measuring the fair value of similar debt instruments, which do not have an associated convertible feature. The carrying amount of the equity component representing the conversion option for the Notes was recorded as a debt discount, which was being amortized to interest expense. On January 1, 2021, the Company early adopted ASU No. 2020-06, Accounting for Convertible Instruments and Contracts in an Entity’s Own Equity, which is intended to simplify the accounting for convertible instruments. The Company adopted the new standard using the modified retrospective method, and accordingly, recorded a net reduction to accumulated deficit of $9.0 million, a decrease to additional paid-in capital of $85.8 million, and an increase to convertible senior notes, net - long-term of $76.8 million to reflect the impact of the accounting change. Beginning January 1, 2021, the Notes have been accounted for as a single liability measured at amortized cost, as no other embedded features require bifurcation and recognition as derivatives.

The net carrying amount of the Notes on the consolidated balance sheets consisted of the following (in thousands):


	December 31, 2023		December 31, 2022
Principal amount	$	287,500	$	287,500
Unamortized debt issuance costs	(2,465)		(4,268)
Net carrying amount	$	285,035	$	283,232

The Notes will have a dilutive effect to the extent the average market price per share of common stock for a given reporting period exceeds the conversion price of $112.57. As of December 31, 2023 and 2022, the if-converted value of the Notes did not exceed the principal amount.

As of December 31, 2023, the unamortized debt issuance costs of $2.5 million associated with the Notes will be amortized to interest expense, at an effective interest rate of 2.2% over the remaining period of approximately 1.3 years.

In October 2023, the Company was notified that additional interest beyond the 1.50% per annum had been accruing on the Notes since May 2021, pursuant to the terms of the indenture. This additional interest continued to accrue at a rate of 0.50% per annum on the outstanding principal amount of the Notes until November 2, 2023. The overdue unpaid interest itself accrued interest at a rate of 2.50% per annum. The Company paid all overdue amounts related to this matter in November 2023.

The following table details interest expense related to the Notes recognized for the years ended December 31, 2023, 2022 and 2021 (in thousands):


	Year Ended December 31,
		2023		2022		2021
Contractual interest expense(1)		$	7,565	$	4,313	$	4,313
Amortization of debt issuance costs		1,803		1,896		1,727

Total interest expense		$	9,368	$	6,209	$	6,040

(1) Contractual interest expense for the year ended December 31, 2023 includes $3.3 million of additional interest as discussed above.

Capped Call Transactions

In connection with the issuance of the Notes, the Company entered into Capped Call Transactions in May 2020 with certain counterparties at a net cost of $34.1 million. The Capped Call Transactions are intended to reduce potential dilution to holders of the Company’s common stock beyond the conversion price of $112.57, up to a conversion price of $173.18 on any conversion of the Notes, or to offset any cash payments the Company is required to make in excess of the principal amount of such converted Notes, as the case may be, with such reduction or offset subject to a cap. The cap price of the Capped Call Transactions is initially $173.18 per share of the Company’s common stock, representing a premium of 100% above the last reported sale price of $86.59 per share of the Company’s common stock on May 12, 2020, and is subject to certain adjustments under the terms of the Capped Call Transactions. Conditions that cause adjustments to the initial strike price of the Capped Call Transactions mirror conditions that result in corresponding adjustments for the Notes.

For accounting purposes, the Capped Call Transactions are separate transactions, and not part of the terms of the Notes, while they are integrated for federal tax purposes. As these transactions met certain criteria under the applicable accounting guidance, the Capped Call Transactions were recorded in stockholders' equity and were not accounted for as derivatives. The cost of the Capped Call Transactions was recorded as a reduction of the Company’s additional paid-in capital in the Company’s consolidated balance sheet and will not be remeasured.

Line of Credit

In the second quarter of 2022, the Company entered into a three-year Revolving Line of Credit Agreement that provided the Company with a maximum principal borrowing amount of $100.0 million (Line of Credit), reduced by any letters of credit issued and outstanding under a $15.0 million letter of credit sub-limit. On August 2, 2023, the Revolving Line of Credit Agreement was amended to reduce the maximum principal borrowing amount to $50.0 million for the remainder of the term, limited to a percentage of eligible accounts receivable during the third quarter of 2023.

The Company terminated the Revolving Line of Credit Agreement in January 2024, with no borrowings made thereunder.

Promissory Note Payable

In connection with the acquisition of Capillary Biomedical, Inc. (see Note 12, “Acquisitions”), the Company assumed a $4.7 million promissory note payable. The promissory note accrues interest at the rate of 5.0% per year, and becomes due and payable upon the first sale or license of the commercialized product. At December 31, 2023 and 2022, the loan balance of $4.7 million was included as a component of other long-term liabilities on the consolidated balance sheets.

- Definition

The entire disclosure for information about short-term and long-term debt arrangements, which includes amounts of borrowings under each line of credit, note payable, commercial paper issue, bonds indenture, debenture issue, own-share lending arrangements and any other contractual agreement to repay funds, and about the underlying arrangements, rationale for a classification as long-term, including repayment terms, interest rates, collateral provided, restrictions on use of assets and activities, whether or not in compliance with debt covenants, and other matters important to users of the financial statements, such as the effects of refinancing and noncompliance with debt covenants.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 470
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1B
-Subparagraph (h)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481139/470-20-50-1B

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 235
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-Name Accounting Standards Codification
-Section S99
-Paragraph 1
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Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
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-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481139/470-20-50-1I

+ Details

Business Segment and Geographic Information - Geographical Markets (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Disaggregation of Revenue [Line Items]
Total Sales	$ 196,796	$ 220,502	$ 747,718	$ 801,217	$ 702,799
United States
Disaggregation of Revenue [Line Items]
Total Sales			554,878	588,765	524,907
Outside the United States
Disaggregation of Revenue [Line Items]
Total Sales			$ 192,840	$ 212,452	$ 177,892

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References + Details

- Definition

Amount, excluding tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value added and excise.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 924
-SubTopic 10
-Name Accounting Standards Codification
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Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 32
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-32

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
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Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
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-Paragraph 22
-Subparagraph (a)
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Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
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-Section 50
-Paragraph 32
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-32

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
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-Name Accounting Standards Codification
-Section 50
-Paragraph 41
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-41

Reference 11: http://www.xbrl.org/2003/role/disclosureRef
-Topic 606
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 4
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479806/606-10-50-4

+ Details

Short-Term Investments (Tables)

12 Months Ended

Dec. 31, 2023

Investments, Debt and Equity Securities [Abstract]

Schedule of Estimated Fair Value of Short-Term Investments

The following represents a summary of the estimated fair value of short-term investments at December 31, 2023 and 2022 (in thousands):


At December 31, 2023	Amortized Cost		Gross Unrealized Gain		Gross Unrealized Loss		Estimated Fair Value
Available-for-sale securities:
U.S. Government-sponsored enterprises	$	181,851	$	518	$	(215)	$	182,154
U.S. Treasury securities	114,714		318		(28)		115,004
Commercial paper	72,505		33		(27)		72,511
Corporate debt securities	39,225		156		(6)		39,375

Total	$	408,295	$	1,025	$	(276)	$	409,044


At December 31, 2022	Amortized Cost		Gross Unrealized Gain		Gross Unrealized Loss		Estimated Fair Value
Available-for-sale securities:
U.S. Government-sponsored enterprises	$	100,602	$	21	$	(615)	$	100,008
U.S. Treasury securities	213,105		3		(1,947)		211,161
Commercial paper	112,812		6		(208)		112,610
Corporate debt securities	18,218		—		(104)		18,114
Supranational bonds	2,504		—		(13)		2,491
Total	$	447,241	$	30	$	(2,887)	$	444,384

Schedule of Contractual Maturities of Available -For-Sale Debt Securities

The contractual maturities of available-for-sale debt securities as of December 31, 2023, were as follows (in thousands):


	Years to Maturity
At December 31, 2023	Within One Year		One to Two Years		Two to Three Years		Estimated Fair Value
U.S. Government-sponsored enterprises	$	86,875	$	56,647	$	38,632	$	182,154
U.S. Treasury securities	74,214		40,790		—		115,004
Commercial paper	72,511		—		—		72,511
Corporate debt securities	12,620		26,755		—		39,375

Total	$	246,220	$	124,192	$	38,632	$	409,044

Stockholders' Equity - Common Stock Warrants (Details) - Common Stock Warrant Expiring March 2027	Dec. 31, 2023 $ / shares shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Warrants exercise price (in dollars per share) \| $ / shares	$ 23.50
Warrants outstanding (in shares) \| shares	193,788

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

+ Details

Summary of Significant Accounting Policies - Reconciliation of Change in Estimated Warranty Liabilities (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Movement in Standard and Extended Product Warranty Accrual, Increase (Decrease) [Roll Forward]
Balance at beginning of the period	$ 36,537	$ 30,401	$ 22,075
Provision for warranties issued during the period	35,690	32,699	27,604
Settlements made during the period	(32,617)	(25,447)	(18,768)
Decreases in warranty estimates	(2,437)	(1,116)	(510)
Balance at end of the period	37,173	36,537	30,401
Other current liabilities	18,135	17,280
Other long-term liabilities	19,038	19,257
Total warranty reserve	$ 37,173	$ 36,537	$ 30,401

Composition of Certain Financial Statement Items - Inventory (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Raw materials	$ 42,783	$ 39,207
Work-in-process	44,026	18,571
Finished goods	71,128	53,339
Total inventories	$ 157,937	$ 111,117

Summary of Significant Accounting Policies - Numerator and Denominator of the Basic and Diluted Net Income (Loss) Per Share Computations (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Net income (loss) - basic			$ (222,611)	$ (94,594)	$ 15,566
Net income (loss) - diluted			$ (222,611)	$ (94,594)	$ 15,566
Weighted average shares outstanding - basic (in shares)	65,369,000	64,384,000	64,969,000	64,146,000	63,000,000
Dilutive common shares equivalents - Warrants to purchase common stock (in shares)			0	0	157,000
Weighted average shares outstanding - diluted (in shares)	65,369,000	64,384,000	64,969,000	64,146,000	64,349,000
Options to purchase common stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Dilutive common stock equivalents - Incremental common shares attributable to dilutive effect (in shares)			0	0	1,129,000
Unvested restricted stock units
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Dilutive common stock equivalents - Incremental common shares attributable to dilutive effect (in shares)			0	0	62,000
Awards to be granted under the ESPP
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Dilutive common stock equivalents - Incremental common shares attributable to dilutive effect (in shares)			0	0	1,000

Commitments and Contingencies (Details) $ in Millions	Dec. 31, 2023 USD ($)
Commitments and Contingencies Disclosure [Abstract]
Unsecured letter of credit outstanding	$ 4.9
Purchase obligation	189.2
Purchase obligation due within one year	$ 181.5

Income Taxes - Income (Loss) Before Provision for Income Taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Income Tax Disclosure [Abstract]
United States	$ (135,411)	$ (94,033)	$ 15,211
Foreign	(84,843)	1,181	690
Income (loss) before income taxes	$ (220,254)	$ (92,852)	$ 15,901

- Definition

Amount of income (loss) from continuing operations, including income (loss) from equity method investments, before deduction of income tax expense (benefit), and income (loss) attributable to noncontrolling interest.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 944
-SubTopic 220
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-04(11))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483586/944-220-S99-1

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 22
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-22

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 30
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-30

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 32
-Subparagraph (f)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-32

Reference 5: http://www.xbrl.org/2003/role/exampleRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 31
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-31

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 32
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482810/280-10-50-32

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Topic 942
-SubTopic 235
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-05(b)(2))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479557/942-235-S99-1

Reference 8: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Section 25
-Paragraph 1
-SubTopic 20
-Topic 940
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481913/940-20-25-1

Reference 9: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 220
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03(10))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483621/220-10-S99-2

Reference 10: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 942
-SubTopic 220
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-04(15))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483589/942-220-S99-1

+ Details

Fair Value Measurements

12 Months Ended

Dec. 31, 2023

Fair Value Disclosures [Abstract]

Fair Value Measurements

Authoritative guidance on fair value measurements defines fair value, and provides a consistent framework for measuring fair value and for disclosures of each major asset and liability category measured at fair value on either a recurring or a nonrecurring basis. Fair value is intended to reflect an assumed exit price, representing the amount that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants. As such, fair value is a market-based measurement that should be determined based on assumptions that market participants would use in pricing an asset or liability. As a basis for considering such assumptions, the authoritative guidance establishes a three-tier fair value hierarchy, which prioritizes the inputs used in measuring fair value as follows:


Level 1:						Observable inputs such as unadjusted quoted prices in active markets that are accessible at the measurement date for identical, unrestricted assets or liabilities.

Level 2:						Inputs, other than quoted prices in active markets, that are observable either directly or indirectly for substantially the full term of the asset or liability.

Level 3:						Unobservable inputs in which there is little or no market data and that are significant to the fair value of the assets or liabilities, which require the reporting entity to develop its own valuation techniques that require input assumptions.


	Fair Value Measurements at December 31, 2023
	Total		Level 1		Level 2		Level 3
Assets
Cash equivalents(1)	$	48,033	$	48,033	$	—	$	—
U.S. Government-sponsored enterprises	182,154		—		182,154		—
U.S. Treasury securities	115,004		115,004		—		—
Commercial paper	72,511		—		72,511		—
Corporate debt securities	39,375		—		39,375		—

Total assets	$	457,077	$	163,037	$	294,040	$	—


	Fair Value Measurements at December 31, 2022
	Total		Level 1		Level 2		Level 3
Assets
Cash equivalents(1)	$	150,742	$	150,742	$	—	$	—
U.S. Government-sponsored enterprises	100,008		—		100,008		—
U.S. Treasury securities	211,161		211,161		—		—
Commercial paper	112,610		—		112,610		—
Corporate debt securities	18,114		—		18,114		—
Supranational bonds	2,491		—		2,491		—
Total assets	$	595,126	$	361,903	$	233,223	$	—

(1)Generally, cash equivalents include money market funds and investments with a maturity of three months or less from the date of purchase.

The Company’s Level 2 financial instruments are valued using market prices on less active markets with observable valuation inputs such as interest rates and yield curves. The Company obtains the fair value of Level 2 financial instruments from quoted market prices, calculated prices or quotes from third-party pricing services. The Company validates these prices through independent valuation testing and review of portfolio valuations provided by the Company’s investment managers.

- Definition

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

+ References + Details

Commitments and Contingencies	12 Months Ended
Commitments and Contingencies	Dec. 31, 2023
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Legal and Regulatory Matters On September 8, 2023, a purported stockholder of the Company filed a putative securities class action complaint (captioned Lowe v. Tandem Diabetes Care, Inc., et al, Case No. 23-cv-1657) in the United States District Court for the Southern District of California against the Company and certain of the Company’s current executive officers. The complaint generally alleges that defendants violated Sections 10(b) and 20(a) of the Securities Exchange Act of 1934, as amended, by failing to properly account for and disclose the full impact that COVID-19, inflation, and the sales of competitors’ products were having on the Company’s sales and revenue. The complaint seeks unspecified monetary damages and other relief. Although the Company intends to vigorously defend against this claim, there is no guarantee that the Company will prevail. Accordingly, the Company is unable to determine the ultimate outcome of this lawsuit or determine the amount or range of potential losses associated with the lawsuit. From time to time, the Company is involved in various other legal proceedings, regulatory matters, and other disputes or claims arising from or related to claims incident to the normal course of the Company’s business activities, including actions with respect to intellectual property, data privacy, employment, regulatory, product liability and contractual matters. Although the results of such legal proceedings and claims cannot be predicted with certainty, as of December 31, 2023 the Company believes it is not currently a party to any legal proceedings, regulatory matters, or other disputes or claims for which a material loss was considered probable or for which the amount (or range) of loss was reasonably estimable. However, regardless of the merit of the claims raised or the outcome, legal proceedings may have an adverse impact on the Company as a result of defense and settlement costs, diversion of management time and resources, and other factors. Letters of Credit In connection with one of the Company’s operating leases (see Note 6, “Leases”), the Company has a $4.9 million unsecured irrevocable standby letter of credit arrangement with a bank, under which the landlord of the building is the beneficiary. The Company is required to maintain the standby letter of credit throughout the term of the lease, which expires in April 2035. Purchase Obligations The Company has agreements with suppliers and other parties to purchase inventory, other goods and services and long-lived assets. Product inventory obligations consist primarily of purchase order commitments for raw materials used in the production of insulin pumps and cartridges, and finished goods infusion sets. Cancellation of outstanding purchase orders is generally allowed under the standard terms of our purchase order agreements, but may require payment of costs incurred through the date of cancellation. At December 31, 2023, obligations under our purchase agreements totaled approximately $189.2 million, of which approximately $181.5 million is scheduled to be received and become payable within one-year.

Subsequent Event	12 Months Ended
Subsequent Event	Dec. 31, 2023
Subsequent Events [Abstract]
Subsequent Event	Subsequent EventPLACEHOLDER

Business Segment and Geographic Information - Additional Information (Details) - segment	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Revenue, Major Customer [Line Items]
Number of operating segments	1
United States \| Revenue from Contract with Customer Benchmark \| Customer Concentration Risk
Revenue, Major Customer [Line Items]
Customers accounted for 10% or more	64.00%	65.00%	67.00%
Outside the United States \| Revenue from Contract with Customer Benchmark \| Customer Concentration Risk
Revenue, Major Customer [Line Items]
Customers accounted for 10% or more	99.00%	96.00%	95.00%

Composition of Certain Financial Statement Items - Accounts Receivable (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Accounts receivable	$ 110,453	$ 119,044
Less: allowance for credit losses	(4,898)	(4,327)	$ (4,249)	$ (3,857)
Accounts receivable, net	$ 105,555	$ 114,717

Short-Term Investments

12 Months Ended

Dec. 31, 2023

Investments, Debt and Equity Securities [Abstract]

Short-Term Investments

The Company invests in marketable securities primarily consisting of debt instruments of the U.S. Government, U.S. Government-sponsored enterprises, and financial institutions and corporations with strong credit ratings. The following represents a summary of the estimated fair value of short-term investments at December 31, 2023 and 2022 (in thousands):


At December 31, 2023	Amortized Cost		Gross Unrealized Gain		Gross Unrealized Loss		Estimated Fair Value
Available-for-sale securities:
U.S. Government-sponsored enterprises	$	181,851	$	518	$	(215)	$	182,154
U.S. Treasury securities	114,714		318		(28)		115,004
Commercial paper	72,505		33		(27)		72,511
Corporate debt securities	39,225		156		(6)		39,375

Total	$	408,295	$	1,025	$	(276)	$	409,044


At December 31, 2022	Amortized Cost		Gross Unrealized Gain		Gross Unrealized Loss		Estimated Fair Value
Available-for-sale securities:
U.S. Government-sponsored enterprises	$	100,602	$	21	$	(615)	$	100,008
U.S. Treasury securities	213,105		3		(1,947)		211,161
Commercial paper	112,812		6		(208)		112,610
Corporate debt securities	18,218		—		(104)		18,114
Supranational bonds	2,504		—		(13)		2,491
Total	$	447,241	$	30	$	(2,887)	$	444,384

The contractual maturities of available-for-sale debt securities as of December 31, 2023, were as follows (in thousands):


	Years to Maturity
At December 31, 2023	Within One Year		One to Two Years		Two to Three Years		Estimated Fair Value
U.S. Government-sponsored enterprises	$	86,875	$	56,647	$	38,632	$	182,154
U.S. Treasury securities	74,214		40,790		—		115,004
Commercial paper	72,511		—		—		72,511
Corporate debt securities	12,620		26,755		—		39,375

Total	$	246,220	$	124,192	$	38,632	$	409,044

The Company has classified all marketable securities, regardless of maturity, as short-term investments based upon the Company’s ability and intent to use any of those marketable securities to satisfy the Company’s liquidity requirements.

The Company reviews the portfolio of available-for-sale debt securities quarterly to determine if any investment is impaired due to changes in credit risk or other potential valuation concerns. Unrealized losses on available-for-sale debt securities at December 31, 2023 were primarily due to an increase in market interest rates after certain debt securities were purchased. The Company does not intend to sell the available-for-sale debt securities that are in an unrealized loss position, and it is not more likely than not that the Company will be required to sell these debt securities before recovery of their amortized cost bases, which may be at maturity. Based on the credit quality of the available-for-sale debt securities in an unrealized loss position, and the Company’s estimates of future cash flows to be collected from those securities, the Company believes the unrealized losses are not credit losses. Accordingly, the Company did not record an allowance for credit losses related to its available-for-sale debt securities at December 31, 2023 and 2022.

Leases - Future Minimum Payments Under Non-cancellable Operating Leases (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Leases [Abstract]
2024	$ 17,065
2025	17,023
2026	17,068
2027	17,333
2028	13,840
Thereafter	90,004
Total undiscounted lease payments	172,333
Less: amount representing interest	(41,701)
Present value of operating lease liabilities	130,632
Less: current portion of operating lease liabilities	(17,060)	$ (13,121)
Operating lease liabilities - long-term	$ 113,572	$ 123,524

Fourth Quarter Financial Data (Unaudited) (Tables)

12 Months Ended

Dec. 31, 2023

Quarterly Financial Information Disclosure [Abstract]

Quarterly Financial Information


	For the Quarter Ended
	December 31, 2023		December 31, 2022
Sales	$	196,796	$	220,502
Gross profit	$	93,295	$	115,523
Operating expenses	$	128,355	$	133,300
Operating loss	$	(35,060)	$	(17,777)
Net loss	$	(30,002)	$	(15,852)
Net loss per share, basic and diluted	$	(0.46)	$	(0.25)
Weighted average shares used to compute basic and diluted net loss per share	65,369		64,384

Stockholders' Equity - Summary of Stock Option Activities for 2006 Plan and 2013 Plan (Detail) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Options, Outstanding at beginning of period (in shares)	4,442,313	4,814,846	5,803,505
Options, Granted (in shares)	0	83,008	355,008
Options, Exercised (in shares)	(72,536)	(280,275)	(1,128,791)
Options, Canceled/forfeited (in shares)	(473,773)	(175,266)	(214,876)
Options, Outstanding at end of period (in shares)	3,896,004	4,442,313	4,814,846	5,803,505
Options, Vested and expected to vest at December 31, 2023 (in shares)	3,890,496
Options, Exercisable at December 31, 2023 (in shares)	3,675,678
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Abstract]
Weighted-Average Exercise Price Per Share, Outstanding at beginning of period (in dollars per share)	$ 57.95	$ 57.08	$ 52.08
Weighted-Average Exercise Price Per Share, Granted (in dollars per share)	0	65.28	86.68
Weighted-Average Exercise Price Per Share, Exercised (in dollars per share)	17.86	32.58	37.05
Weighted-Average Exercise Price Per Share, Canceled/forfeited (in dollars per share)	90.14	77.93	76.29
Weighted-Average Exercise Price Per Share, Outstanding at end of period (in dollars per share)	54.79	$ 57.95	$ 57.08	$ 52.08
Weighted-Average Exercise Price Per Share, Vested and expected to vest at December 31, 2023 (in dollars per share)	54.75
Weighted-Average Exercise Price Per Share, Exercisable at December 31, 2023 (in dollars per share)	$ 53.11
Weighted- Average Remaining Contractual Life (in years)	5 years 3 months 18 days	6 years 1 month 13 days	7 years 25 days	7 years 10 months 24 days
Weighted-Average Remaining Contractual Life, Vested and expected to vest	5 years 3 months 18 days
Weighted-Average Remaining Contractual Life, Exercisable	5 years 2 months 8 days
Aggregate intrinsic value outstanding balance	$ 11,703	$ 30,236	$ 452,081	$ 268,649
Aggregate Intrinsic Value, Exercised	1,400	13,473	86,149
Aggregate Intrinsic Value, Canceled/forfeited/expired	95	$ 2,143	$ 6,963
Aggregate Intrinsic Value, Vested and expected to vest	11,703
Aggregate Intrinsic Value, Exercisable	$ 11,703

Acquisitions	12 Months Ended
Acquisitions	Dec. 31, 2023
Business Combination and Asset Acquisition [Abstract]
Acquisitions	Acquisitions AMF Medical Acquisition On December 10, 2022, the Company entered into a Share Purchase Agreement (Purchase Agreement) with AMF Medical SA, a corporation organized and existing under the laws of Switzerland (AMF Medical), and its shareholders to acquire all of the registered shares of AMF Medical (Transaction). AMF Medical is the developer of the Sigi Patch Pump, which is designed to be an ergonomic, rechargeable patch pump that reduces the burden of managing diabetes through its use of pre-filled insulin cartridges. The Sigi Patch Pump is under development and not commercially available. On January 19, 2023, the Company completed the acquisition of AMF Medical under the terms of the Purchase Agreement. The total aggregate consideration for the Transaction includes a previous strategic investment of Swiss Francs (CHF) 8.0 million made in the third quarter of 2022, a cash payment of CHF 62.4 million paid at the closing of the Transaction, and additional contingent earnout payments of up to CHF 129.6 million. The contingent earnout payments become payable upon the achievement of certain milestones, and are comprised of a payment of up to CHF 38.4 million upon the successful completion of key development milestones over the two years following the closing date of the Transaction, and a payment of up to CHF 91.2 million upon obtaining regulatory clearance from the United States Food and Drug Administration of an automated controller enabled (ACE) pump. The contingent consideration will be recognized as each contingency is resolved and the respective consideration is paid or becomes payable. As of December 31, 2023, the contingencies related to the earnout milestones were not yet resolved and, therefore, the related amounts were not included in the fair value of the asset acquired and were not recognized as a liability on the consolidated balance sheet at December 31, 2023. The Company funded the initial closing payment using existing cash balances. As of December 31, 2022, the previous strategic investment was included as a component of other long-term assets on the consolidated balance sheet (see Note 2, “Summary of Significant Accounting Policies”). The transaction was accounted for as an asset acquisition as substantially all the value of the gross assets was concentrated in a single asset. The Company recorded a $78.8 million charge in 2023 representing the value of acquired in-process research and development assets with no alternative future use, and acquisition related expenses, on its consolidated statements of operations in acquired in-process research and development expenses. The Company’s results of operations for the year ended December 31, 2023 included the operating results of AMF Medical since the date of acquisition. Capillary Biomedical Acquisition On July 21, 2022, the Company acquired Capillary Biomedical, Inc. (Capillary Biomedical), an infusion set developer, for total cash consideration of $24.7 million, and the assumption of $4.7 million of long-term debt (see Note 7, “Debt”). Capillary Biomedical’s extended-wear infusion set technology is currently in development and is not yet commercially available. The Company funded the purchase price using existing cash balances. The transaction was accounted for as an asset acquisition as substantially all the value of the gross assets was concentrated in a single asset. The Company recorded a $31.0 million charge in 2022 representing the value of acquired in-process research and development assets with no alternative future use, and acquisition related expenses, on its consolidated statements of operations in acquired in-process research and development expenses.

Business Segment and Geographic Information (Tables)

12 Months Ended

Dec. 31, 2023

Segment Reporting [Abstract]

Schedule of Disaggregation of Revenue

The table below sets forth revenues for the Company’s two primary geographical markets, based on the geographic location to which its products are shipped (in thousands):


	Year Ended December 31,
		2023		2022		2021
United States		$	554,878	$	588,765	$	524,907
Outside the United States		192,840		212,452		177,892
Total Sales		$	747,718	$	801,217	$	702,799