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Cover Page - shares	3 Months Ended
Cover Page - shares	Mar. 31, 2020	Apr. 21, 2020
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Mar. 31, 2020
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	11075 Roselle Street
Entity Address, Postal Zip Code	92121
Entity Address, City or Town	San Diego,
Entity Address, State or Province	CA
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 Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		60,102,978
Amendment Flag	false
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	Q1
Entity Central Index Key	0001438133
Current Fiscal Year End Date	--12-31

CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Current assets:
Cash and cash equivalents	$ 74,485	$ 51,175
Short-term investments	85,723	125,283
Accounts receivable, net	53,962	46,585
Inventories	60,469	49,073
Prepaid and other current assets	6,234	4,025
Total current assets	280,873	276,141
Property and equipment, net	37,626	32,923
Operating lease right-of-use assets	23,014	15,561
Other long-term assets	1,814	1,485
Total assets	343,327	326,110
Current liabilities:
Accounts payable	21,783	17,745
Accrued expenses	5,896	8,014
Employee-related liabilities	22,059	28,320
Deferred revenue	4,377	3,869
Common stock warrants	25,290	23,509
Operating lease liabilities	8,320	6,320
Other current liabilities	11,922	11,619
Total current liabilities	99,647	99,396
Operating lease liabilities - long-term	19,547	14,063
Other long-term liabilities	16,957	17,672
Total liabilities	136,151	131,131
Commitments and contingencies (Note 9)
Stockholders’ equity:
Common stock, $0.001 par value; 200,000 shares authorized, 60,071 and 59,396 shares issued and outstanding at March 31, 2020 (unaudited) and December 31, 2019, respectively.	60	59
Additional paid-in capital	847,056	819,626
Accumulated other comprehensive income (loss)	(245)	122
Accumulated deficit	(639,695)	(624,828)
Total stockholders’ equity	207,176	194,979
Total liabilities and stockholders’ equity	$ 343,327	$ 326,110

CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) - $ / shares	Mar. 31, 2020	Dec. 31, 2019
Statement of Financial Position [Abstract]
Common stock, par value (in usd per share)	$ 0.001	$ 0.001
Common stock, shares authorized (in shares)	200,000,000	200,000,000
Common stock, shares issued (in shares)	60,071,000	59,396,000
Common stock, shares outstanding (in shares)	60,071,000	59,396,000

CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE LOSS - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Income Statement [Abstract]
Sales	$ 97,926	$ 65,995
Cost of sales	47,665	32,642
Gross profit	50,261	33,353
Operating expenses:
Selling, general and administrative	49,717	34,961
Research and development	14,117	9,389
Total operating expenses	63,834	44,350
Operating loss	(13,573)	(10,997)
Other income (expense), net:
Interest and other income	726	757
Interest and other expense	0	(6)
Change in fair value of common stock warrants	(1,922)	(12,746)
Total other expense, net	(1,196)	(11,995)
Loss before income taxes	(14,769)	(22,992)
Income tax expense	98	0
Net loss	(14,867)	(22,992)
Other comprehensive loss:
Unrealized gain on short-term investments	42	50
Foreign currency translation gain (loss)	(409)	4
Comprehensive loss	$ (15,234)	$ (22,938)
Net loss per share, basic and diluted (in dollars per share)	$ (0.25)	$ (0.40)
Weighted average shares used to compute basic and diluted net loss per share (in shares)	59,740	57,771

CONDENSED CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Accumulated Other Comprehensive Income (Loss)	Accumulated Deficit
Beginning balance (shares) at Dec. 31, 2018		57,554,000
Beginning balance at Dec. 31, 2018	$ 131,275	$ 57	$ 731,306	$ (13)	$ (600,075)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise of stock options (in shares)		409,000
Exercise of stock options	1,899	$ 1	1,898
Exercise of common stock warrants (shares)		19,000
Exercise of common stock warrants	64		64
Fair value of common stock warrants at time of exercise	910		910
Stock-based compensation	9,752		9,752
Unrealized gain on short-term investments	50			50
Foreign currency translation gain (loss)	4			4
Net loss	(22,992)				(22,992)
Ending balance (shares) at Mar. 31, 2019		57,982,000
Ending balance at Mar. 31, 2019	120,962	$ 58	743,930	41	(623,067)
Beginning balance (shares) at Dec. 31, 2019		59,396,000
Beginning balance at Dec. 31, 2019	194,979	$ 59	819,626	122	(624,828)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise of stock options (in shares)		673,000
Exercise of stock options	11,475	$ 1	11,474
Exercise of common stock warrants (shares)		2,000
Exercise of common stock warrants	7		7
Fair value of common stock warrants at time of exercise	141		141
Stock-based compensation	15,808		15,808
Unrealized gain on short-term investments	42			42
Foreign currency translation gain (loss)	(409)			(409)
Net loss	(14,867)				(14,867)
Ending balance (shares) at Mar. 31, 2020		60,071,000
Ending balance at Mar. 31, 2020	$ 207,176	$ 60	$ 847,056	$ (245)	$ (639,695)

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Operating Activities
Net loss	$ (14,867)	$ (22,992)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization expense	1,830	1,438
Provision for expected credit losses	862	342
Provision (benefit) for inventory obsolescence	(363)	679
Change in fair value of common stock warrants	1,922	12,746
Amortization of discount on short-term investments	(66)	(94)
Stock-based compensation expense	15,865	9,834
Other	19	27
Changes in operating assets and liabilities:
Accounts receivable, net	(8,292)	1,821
Inventories, net	(11,095)	(3,690)
Prepaid and other current assets	(2,231)	(1,036)
Other long-term assets	(383)	(225)
Accounts payable	4,294	4,376
Accrued expenses	(2,124)	(553)
Employee-related liabilities	(6,253)	(6,982)
Deferred revenue	1,524	861
Other current liabilities	431	(2,120)
Other long-term liabilities	(1,704)	1,444
Net cash used in operating activities	(20,631)	(4,124)
Investing Activities
Purchases of short-term investments	(9,727)	(42,914)
Proceeds from maturities of short-term investments	30,859	43,700
Proceeds from sales of short-term investments	18,550	1,400
Purchases of property and equipment	(6,766)	(1,408)
Net cash provided by investing activities	32,916	778
Financing Activities
Proceeds from exercise of common stock warrants	7	64
Proceeds from issuance of common stock under Company stock plans	11,474	1,898
Net cash provided by financing activities	11,481	1,962
Effect of foreign exchange rate changes on cash	(456)	3
Net increase (decrease) in cash and cash equivalents	23,310	(1,381)
Cash and cash equivalents at beginning of period	51,175	41,826
Cash and cash equivalents at end of period	74,485	40,445
Supplemental disclosures of cash flow information
Income taxes paid	91	0
Supplemental schedule of non-cash investing and financing activities
Right-of-use assets obtained in exchange for operating lease obligations	8,805	3,053
Property and equipment included in accounts payable	$ 1,880	$ 130

Organization and Basis of Presentation	3 Months Ended
Organization and Basis of Presentation	Mar. 31, 2020
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 with an innovative approach to the design, development and commercialization of products for people with insulin-dependent diabetes. The Company 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 subsidiary in Canada. 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 principally focus on the t:slim X2 Insulin Delivery System (t:slim X2), the Company’s flagship pump platform which is capable of remote feature updates and is designed to display continuous glucose monitoring (CGM) sensor information directly on the pump home screen. The Company’s insulin pump products are compatible with the t:connect cloud-based data management application (t:connect) and the Tandem Device Updater, a Mac and PC-compatible tool for the remote update of the Company’s insulin pump software. 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 disposable 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. The Company has commercially launched seven insulin pumps in the United States since 2012 and two pumps outside the United States since 2018. Four of the insulin pumps have featured integration with CGM technology, of which two have also featured an automated insulin delivery (AID) algorithm. In June 2018, the t:slim X2 was the first insulin pump designated as compatible with integrated CGM (iCGM) devices; in February 2019, the t:slim X2 was the first insulin pump in a new device category called Alternate Controller Enabled Infusion Pumps (ACE pumps); and in December 2019, Control-IQ technology for the t:slim X2 insulin pump was the first automated insulin dosing software in a new interoperable automated glycemic controller category. The Company believes that the three new classifications by the United States Food and Drug Administration (FDA) for the interoperability of devices for AID will help support continued rapid innovation by streamlining the regulatory pathway for integrated products. As of March 31, 2020, the Company had $160.2 million in cash and cash equivalents and short-term investments. The Company has incurred operating losses since its inception and had an accumulated deficit of $639.7 million as of March 31, 2020, which included a net loss of $14.9 million for the three months ended March 31, 2020. Management believes that the cash, cash equivalents and short-term investments on hand will be sufficient to satisfy the Company’s liquidity requirements for at least the next 12 months from the date of this filing. The Company’s ability to execute on its business strategy, meet its future liquidity requirements, and achieve and maintain profitable operations, is dependent on a number of factors, including its ability to continue to gain market acceptance of its products and achieve a level of revenues adequate to support its cost structure, achieve renewal pump sales objectives, develop and launch new products, expand the commercialization of products into new international markets, maximize manufacturing efficiencies, satisfy increasing production requirements, leverage the investments made in its sales, clinical, marketing and customer support organizations, and operate its business and manufacture and sell products without infringing on third-party intellectual property rights. The Company has funded its operations primarily through cash collected from product sales, private and public offerings of equity securities, and through debt financing which has since been fully repaid. The Company may in the future seek additional capital from public or private offerings of equity or debt securities, or it may elect to borrow capital under new credit arrangements or from other sources. If the Company issues equity or debt securities to raise additional funds, its existing stockholders may experience dilution, it may incur significant financing or debt service costs, and the new equity or debt securities may have rights, preferences and privileges senior to those of its existing stockholders. There can be no assurance that equity or debt financing will be available on acceptable terms, or at all. Basis of Presentation and Principles of Consolidation The Company has prepared the accompanying unaudited condensed consolidated financial statements in accordance with accounting principles generally accepted in the United States of America (U.S. GAAP) for interim financial information and pursuant to the instructions to Form 10-Q and Article 10 of Regulation S-X. Accordingly, they do not include all of the information and disclosures required by U.S. GAAP for complete financial statements. In the opinion of management, all adjustments which are of a normal and recurring nature, considered necessary for a fair presentation of the financial information contained herein, have been included. Interim financial results are not necessarily indicative of results anticipated for the full year or any other period(s). These unaudited condensed consolidated financial statements should be read in conjunction with the Company’s audited consolidated financial statements and accompanying notes included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2019 (Annual Report), from which the balance sheet information herein was derived. The condensed consolidated financial statements include the accounts of Tandem Diabetes Care, Inc. and its wholly owned subsidiary in Canada. All significant intercompany balances and transactions have been eliminated in consolidation. The functional currency of our foreign subsidiary is the local currency. The Company translates the financial statements of its foreign subsidiary 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 comprehensive loss and in accumulated other comprehensive income (loss) in the equity section of the Company’s condensed consolidated balance sheets. Foreign exchange gains or losses resulting from balances denominated in a currency other than the functional currency are recognized in interest and other income or interest and other expense in the Company’s condensed consolidated statements of operations. Reclassification Prior year amounts related to the presentation of proceeds from maturities and sales of short-term investments on the Company’s condensed consolidated statement of cash flows, have been reclassified to conform to the current year presentation.

Summary of Significant Accounting Policies

3 Months Ended

Mar. 31, 2020

Accounting Policies [Abstract]

Summary of Significant Accounting Policies

There have been no material changes to the Company’s significant accounting policies during the three months ended March 31, 2020, as compared to those disclosed in the Annual Report.

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.

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, disposable cartridges and infusion sets for the storage and delivery of insulin. The Company views its operations and manages its business as one segment because key operating decisions and resource allocations are made by the CODM using consolidated financial data.

Accounts Receivable

The Company grants credit to various customers in the ordinary course of business and is paid directly by customers who use the 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 risk, review of outstanding invoices, forecasts about the future, and various assumptions and estimates that are believed to be reasonable under the circumstances. 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

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 believes the fair value of its operating lease liabilities at March 31, 2020 approximated their carrying value, based on the borrowing rates that were available for loans with similar terms as of that date. The estimated fair value of certain of the Company’s common stock warrants was determined using the Black-Scholes pricing model as of March 31, 2020 and December 31, 2019 (see Note 5, “Fair Value Measurements”).

Operating Lease Right-of-Use Assets and Liabilities

Lease right-of-use assets represent the Company’s right to use an underlying asset for the lease term and lease liabilities represent their 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 (the Commencement Date) based on the present value of lease payments over the lease term. 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 sheet. Landlord improvement allowances and other such lease incentives are recorded as property and equipment and as reduction of the right-of-use leased assets, and are amortized on a straight-line basis as a reduction to operating lease costs. Leases with an initial term of 12 months or less are expensed as incurred and are not recorded as right-of-use assets on the consolidated balance sheets (see Note 6, “Leases”).

Revenue Recognition

Revenue is generated primarily from sales of insulin pumps, disposable cartridges and infusion sets to individual customers and third-party distributors that resell the products to insulin-dependent diabetes customers. The Company recognizes revenue when it transfers 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.

Revenue Recognition for Arrangements with Multiple Deliverables

The Company considers the individual deliverables in its product offering as 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 is upon delivery. Complementary products, such as t:connect and the Tandem Device Updater, are considered 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 ratably over a four-year period. There is no standalone value for these complementary products. Therefore, the Company determines their value by applying the expected cost plus a margin approach and then allocates the residual to the insulin pumps. Deferred revenue related to these performance obligations that are satisfied over time was included in the following consolidated balance sheet accounts in the amounts shown as of March 31, 2020 and December 31, 2019 (in thousands):



	March 31, 2020		December 31, 2019
Deferred revenue	$	3,833	$	3,465
Other long-term liabilities	6,626		5,656
Total	$	10,459	$	9,121

Sales Returns

The Company offers a 30-day right of return to customers in the U.S. and Canada from the date of shipment of its insulin pumps, provided a physician’s confirmation of the medical reason for the return is received. Estimated allowances for sales returns are based on historical returned quantities as compared to pump shipments in those same periods of return. The return rate is then applied to the sales of the current period to establish a reserve at the end of the period. The return rates used in the reserve are adjusted for known or expected changes in the marketplace when appropriate. The allowance for sales returns is recorded as a reduction of revenue and an increase in deferred revenue in the period in which the related sale is recorded. The amount recorded in deferred revenue on the Company’s consolidated balance sheets for allowances for sales returns was $0.5 million and $0.4 million at March 31, 2020 and December 31, 2019, respectively. Actual product returns have not differed materially from estimated amounts recorded in the accompanying condensed consolidated financial statements.

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 in accordance with the product specifications. Insulin pumps returned to the Company may be refurbished and redeployed. Additionally, the Company offers a six-month warranty on disposable cartridges and infusion sets. Estimated warranty costs are recorded at the time of shipment. We evaluate the reserve quarterly. Warranty costs are primarily estimated based on the current expected product replacement cost and expected replacement rates utilizing historical experience. Recently released versions of the pump may not incur warranty costs in a manner similar to previously released pumps, on which the Company initially bases its warranty estimate of newer pumps. The Company may make further adjustments to the warranty reserve when deemed appropriate, giving additional consideration to length of time the pump version has been in the field and future expectations of performance based on new features and capabilities that may become available through Tandem Device Updater.

The following table provides a reconciliation of the change in product warranty liabilities from December 31, 2019 through March 31, 2020 (in thousands):



Balance at December 31, 2019	$	16,724
Provision for warranties issued during the period	4,814
Settlements made during the period	(3,390		)
Decreases in warranty estimates	(1,387		)
Balance at March 31, 2020	$	16,761

As of March 31, 2020 and December 31, 2019, total product warranty reserves of $16.8 million and $16.7 million, respectively, were included in the following consolidated balance sheet accounts (in thousands):



	March 31, 2020		December 31, 2019
Other current liabilities	$	6,427	$	4,707
Other long-term liabilities	10,334		12,017
Total warranty reserves	$	16,761	$	16,724

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 Amended and Restated 2013 Stock Incentive Plan (2013 Plan), and the fair value of the employees’ purchase rights under the Company’s 2013 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 7, “Stockholders’ Equity”). For awards that vest based on the achievement of service conditions, the Company recognizes expense using the straight-line method less estimated forfeitures based on historical experience.

Net Loss Per Share

Basic net loss per share is calculated by dividing the net loss by the weighted average number of common shares that were outstanding for the period, without consideration for common stock equivalents. Diluted loss per share is calculated in accordance with the treasury stock method and reflects the potential dilution that would occur if securities or other contracts to issue common stock were exercised or converted to common stock. Dilutive common share equivalents are comprised of warrants, potential awards granted pursuant to the ESPP, and stock options outstanding under the Company’s equity incentive plans. For warrants that are recorded as a liability in the accompanying condensed consolidated balance sheets, the calculation of diluted loss per share requires that, to the extent the average market price of the underlying shares for the reporting period exceeds the exercise price of the warrants and the presumed exercise of the warrants is dilutive to loss per share for the period, an adjustment is made to net loss used in the calculation to remove the change in fair value of the warrants from the numerator for the period. Likewise, an adjustment to the denominator is required to reflect the related dilutive shares, if any, under the treasury stock method. For the three months ended March 31, 2020 and 2019, there is no difference in the number of shares used to calculate basic and diluted shares outstanding due to the Company’s net loss position.

Potentially dilutive securities 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):



	Three Months Ended March 31,
	2020	2019
Warrants to purchase common stock	609	686
Options to purchase common stock	5,710	5,475
Awards granted under the ESPP	198	142
	6,517	6,303

Recent Accounting Pronouncements

In June 2016, the Financial Accounting Standards Board (FASB) issued Accounting Standards Update (ASU) No. 2016-13, Financial Instruments – Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments, which modifies the measurement and recognition of credit losses for most financial assets and certain other instruments. The new standard requires the use of forward-looking expected credit loss models based on historical experience, current conditions, and reasonable and supportable forecasts that affect the collectability of the reported amount, which may result in earlier recognition of credit losses under the new standard. The new standard also requires that credit losses related to available-for-sale debt securities be recorded as an allowance through net income (loss) rather than reducing the carrying amount under the prior, other-than-temporary-impairment model. The new standard must be adopted using the modified retrospective approach and was effective for the Company starting in the first quarter of fiscal 2020. The Company determined there was no cumulative-effect transition adjustment to the opening balance of accumulated deficit for recognition of additional credit losses upon adoption of this standard as of January 1, 2020 based on its outstanding accounts receivable, the composition and credit quality of its short-term investments, and current economic conditions as of that date.

In August 2018, the FASB issued ASU No. 2018-13, Fair Value Measurement: Disclosure Framework – Changes to the Disclosure Requirements for Fair Value Measurement, which adds and modifies certain disclosure requirements for fair value measurements. Under the new guidance, entities will no longer be required to disclose the amount of and reasons for transfers between Level 1 and Level 2 of the fair value hierarchy, or valuation processes for Level 3 fair value measurements. However, public companies will be required to disclose the range and weighted average of significant unobservable inputs used to develop Level 3 fair value measurements, and related changes in unrealized gains and losses included in other comprehensive income. The updated guidance was effective for the Company starting in the first quarter of fiscal 2020. As a result, the Company modified certain fair value measurement disclosures primarily related to its Level 3 liabilities (see Note 5, “Fair Value Measurements”).

In December 2019, the FASB issued ASU No. 2019-12, Simplifying the Accounting for Income Taxes, which is intended to simplify various aspects of the income tax accounting guidance, including requirements such as tax basis step-up in goodwill obtained in a transaction that is not a business combination, ownership changes in investments, and interim-period accounting for enacted changes in tax law. ASU 2019-12 is effective for public business entities for fiscal years beginning after December 15, 2020, including interim periods within those fiscal years, and early adoption is permitted. The Company is in the process of assessing the impact of the adoption of the standard on its consolidated financial statements.

Short-Term Investments

3 Months Ended

Mar. 31, 2020

Investments, Debt and Equity Securities [Abstract]

Short-Term Investments

The Company invests in marketable securities consisting of debt instruments of the U.S. Government, and financial institutions and corporations with strong credit ratings. The following represents a summary of the estimated fair value of short-term investments as of March 31, 2020 and December 31, 2019 (in thousands):



At March 31, 2020	Maturity (in years)	Amortized Cost		Gross Unrealized Gain		Gross Unrealized Loss			Estimated Fair Value
Available-for-sale securities:
Commercial paper	Less than 1	$	17,352	$	11	$	—		$	17,363
U.S. Government-sponsored enterprise	Less than 2	20,255		63		—			20,318
U.S. Treasury securities	Less than 1	12,721		93		—			12,814
Corporate debt securities	Less than 2	35,251		39		(62		)	35,228
Total		$	85,579	$	206	$	(62	)	$	85,723



At December 31, 2019	Maturity (in years)	Amortized Cost		Gross Unrealized Gain		Gross Unrealized Loss			Estimated Fair Value
Available-for-sale securities:
Commercial paper	Less than 1	$	24,147	$	10	$	—		$	24,157
U.S. Government-sponsored enterprise	Less than 2	33,073		26		—			33,099
U.S. Treasury securities	Less than 2	17,963		17		(1		)	17,979
Corporate debt securities	Less than 2	50,011		42		(5		)	50,048
Total		$	125,194	$	95	$	(6	)	$	125,283

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 periodically reviews the portfolio of available-for-sale debt securities 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 March 31, 2020 were not significant and were due to changes in interest rates, including credit spreads from perceived increased credit risks as a result of the novel coronavirus (COVID-19) global pandemic. 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 that are 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, at March 31, 2020, the Company has not recorded an allowance for credit losses related to its available-for-sale debt securities.

Accounts Receivable and Inventories

3 Months Ended

Mar. 31, 2020

Accounts Receivable And Inventories Disclosure [Abstract]

Accounts Receivable and Inventories

Inventories

Accounts Receivable

Accounts receivable consisted of the following (in thousands):



	March 31,			December 31,
	2020			2019
Accounts receivable	$	57,346		$	49,889
Less allowance for credit losses	(3,384		)	(3,304		)
Accounts receivable, net	$	53,962		$	46,585

Allowance for Credit Losses

The following table provides a reconciliation of the change in the estimated allowance for expected accounts receivable credit losses for the three months ended March 31, 2020 and 2019 (in thousands):



	For the Three Months Ended
	March 31, 2020			March 31, 2019
Balance at beginning of the period	$	3,304		$	1,837
Provision for expected credit losses	862			342
Write-offs and adjustments, net of recoveries	(782		)	(163		)
Balance at end of the period	$	3,384		$	2,016

Inventories

Inventories consisted of the following as of March 31, 2020 and December 31, 2019 (in thousands):



	March 31, 2020		December 31, 2019
Raw materials	$	31,795	$	20,699
Work-in-process	14,543		16,532
Finished goods	14,131		11,842
Inventories	$	60,469	$	49,073

Fair Value Measurements

3 Months Ended

Mar. 31, 2020

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.

The following table presents information about the Company’s financial assets and liabilities measured at fair value on a recurring basis as of March 31, 2020 and December 31, 2019, and indicates the fair value hierarchy of the valuation techniques utilized by the Company to determine such fair value (in thousands):



			Fair Value Measurements at March 31, 2020
			(Level 1)		(Level 2)		(Level 3)
Assets
Cash equivalents⁽¹⁾	$	69,346	$	69,346	$	—	$	—
Commercial paper	17,363		—		17,363		—
U.S. Government-sponsored enterprise	20,318		—		20,318		—
U.S. Treasury securities	12,814		12,814		—		—
Corporate debt securities	35,228		—		35,228		—
Total assets	$	155,069	$	82,160	$	72,909	$	—

Liabilities
Common stock warrants	$	25,290	$	—	$	—	$	25,290
Total liabilities	$	25,290	$	—	$	—	$	25,290



			Fair Value Measurements at December 31, 2019
			(Level 1)		(Level 2)		(Level 3)
Assets
Cash equivalents⁽¹⁾	$	49,077	$	49,077	$	—	$	—
Commercial paper	24,157		—		24,157		—
U.S. Government-sponsored enterprise	33,099		—		33,099		—
U.S. Treasury securities	17,979		17,979		—		—
Corporate debt securities	50,048		—		50,048		—
Total assets	$	174,360	$	67,056	$	107,304	$	—

Liabilities
Common stock warrants	$	23,509	$	—	$	—	$	23,509
Total liabilities	$	23,509	$	—	$	—	$	23,509


(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.

The Company’s Level 3 liabilities at March 31, 2020 and December 31, 2019 include the Series A warrants issued by the Company in connection with the public offering of common stock in October 2017. The Series A warrants have a term of five years and initially provided holders the right to purchase 4,630,000 shares of the Company’s common stock at an exercise price of $3.50 per share. The Series A warrants were initially valued in the aggregate amount of $5.2 million on the date of issuance utilizing a Black-Scholes pricing model.

The Company reassesses the fair value of the outstanding Series A warrants at each reporting date utilizing a Black-Scholes pricing model. Variables used in the pricing model include the closing market price of the Company’s common stock at the balance sheet date, and estimates of stock price volatility, dividend yield, expected warrant term and risk-free interest rate. The Company develops its estimates based on publicly available historical data. A significant increase (decrease) in any of these inputs in isolation, particularly the market price of the Company’s common stock, would have resulted in a significantly higher (lower) fair value measurement. The assumptions used to estimate the fair values of the outstanding Series A warrants at March 31, 2020 and December 31, 2019 are presented below:



	March 31, 2020		December 31, 2019
Risk-free interest rate	0.3	%	1.6	%
Expected dividend yield	0.0	%	0.0	%
Expected volatility	74.9	%	77.2	%
Expected term (in years)	2.5		2.8

The following table presents a summary of changes in the fair value of the Company’s Level 3 financial liabilities for the three months ended March 31, 2020 and 2019:



	Three Months Ended March 31,
	2020			2019
Balance at beginning of the period	$	23,509		$	17,926
Loss recognized from the change in fair value of common stock warrants	1,922			12,746
Decrease in fair value from warrants exercised during the period	(141		)	(910		)
Balance at end of the period	$	25,290		$	29,762

Of the loss recognized from the change in fair value of common stock warrants for the three months ended March 31, 2020 and 2019, $1.9 million and $12.5 million, respectively, was attributable to the change in the unrealized loss related to warrants outstanding as of March 31, 2020 and 2019.

During the three months ended March 31, 2020 and 2019, the Company issued 2,115 shares and 18,285 shares of common stock, respectively, upon the exercise of Series A warrants issued in October 2017. As of March 31, 2020 and 2019, there were Series A warrants outstanding to purchase 415,200 shares and 492,500 shares, respectively, of the Company’s common stock (see Note 7, “Stockholders’ Equity”).

- 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

Leases

3 Months Ended

Mar. 31, 2020

Leases [Abstract]

Leases

In February 2016, the FASB issued ASU No. 2016-02, Leases. The new standard and its related amendments (collectively referred to as ASC 842) requires lessees to recognize right-of-use assets and corresponding lease liabilities for all leases with lease terms of greater than 12 months. The new standard was effective for the Company starting in the first quarter of fiscal 2019. The Company adopted the new standard using the modified retrospective approach and recognized right-of-use leased assets and corresponding operating lease liabilities of $12.4 million on the consolidated balance sheet as of January 1, 2019. The Company did not restate prior periods. Deferred rent of $1.0 million and $3.8 million as of January 1, 2019 was reclassified from other current liabilities and deferred rent long-term, respectively, to a reduction of the right-of-use leased assets in connection with the adoption of the standard.

The Company’s leases consist primarily of operating leases for general office space, laboratory, manufacturing and warehouse facilities, and equipment. 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 in determining the present value of future lease payments. The Company used the incremental borrowing rate on January 1, 2019 for operating leases that commenced prior to that date. For lease agreements entered into or reassessed after the adoption of ASC 842, the Company combines lease and non-lease components.

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. The depreciable life of assets and leasehold improvements are limited by the expected lease term, unless there is a transfer of title or purchase option that is reasonably certain to be exercised.

In January 2019, the Company entered into a lease agreement for approximately 25,332 square feet of additional general administrative office space (Initial Premises) located on Vista Sorrento Parkway, in San Diego, California (Vista Sorrento Lease). The lease term for the Initial Premises commenced in March 2019 and expires in September 2022. In May 2019, the Company entered into a First Amendment to the Vista Sorrento Lease (First Amendment) to expand the leased premises by adding approximately 33,681 square feet of additional general administrative office space (Expansion Space), and to extend the lease term for the Initial Premises through January 2023. The lease term for the Expansion Space commenced in May 2019 and expires in January 2023. The Company has a one-time option to extend the term of the Vista Sorrento Lease, covering both the Initial Premises and the Expansion Space, for a period of four years. The Company recognized right-of-use leased assets and corresponding operating lease liabilities of $3.1 million on the consolidated balance sheet in the first quarter of 2019 related to the Initial Premises, and $4.7 million related to the First Amendment.

In November 2019, the Company entered into a lease agreement for approximately 94,562 square feet of additional general office space located on Shoreline Drive, in Boise, Idaho (Shoreline Lease). Subject to limited exceptions, the initial lease term is expected to begin on the earlier of (i) the date on which the Company substantially completes certain specified work related to tenant improvements, (ii) the date on which the Company begins use of the premises for their intended purpose, or (iii) July 1, 2020, and will expire 84 months from the first day of the first full month following the start of the lease term. The Company has a one-time option to extend the term of the Shoreline Lease for a period of three years. The Company recognized right-of-use leased assets and corresponding operating lease liabilities of approximately $6.5 million on the consolidated balance sheet on the Commencement Date in the first quarter of 2020. Future minimum payments due under the Shoreline Lease are approximately $8.2 million as of March 31, 2020.

In January 2020, the Company entered into a sub-lease agreement for approximately 30,703 square feet of general office space located on High Bluff Drive, in San Diego, California (High Bluff Lease). The lease term begins in April 2020 and expires in March 2022. The Company recognized right-of-use leased assets and corresponding operating lease liabilities of approximately $2.3 million on the consolidated balance sheet on the Commencement Date in the first quarter of 2020. Future minimum payments due under the High Bluff Lease are approximately $2.4 million as of March 31, 2020.

The Company’s total lease cost recorded in the condensed consolidated statements of operations was $1.8 million and $0.7 million, respectively, for the three months ended March 31, 2020 and 2019, which included $1.7 million and $0.7 million, respectively, of operating lease cost and $0.1 million of short-term lease cost in 2020. Cash paid for amounts included in the measurement of lease liabilities, representing operating cash flows from operating leases, was $1.6 million and $0.9 million for the three months ended March 31, 2020 and 2019, respectively.

Maturities of operating lease liabilities at March 31, 2020 were as follows (in thousands):



Years Ending December 31,
2020 (remaining)	$	5,994
2021	9,422
2022	7,314
2023	3,388
2024	1,881
Thereafter	3,975
Total undiscounted lease payments	31,974
Less: amount representing interest	(4,107		)
Present value of operating lease liabilities	27,867
Less: current portion of operating lease liabilities	(8,320		)
Operating lease liabilities - long-term	$	19,547

As of March 31, 2020, the weighted average remaining lease term for operating leases was 4.1 years and the weighted-average discount rate used to determine the operating lease liabilities was 6.3%. As of December 31, 2019, the weighted average remaining lease term for operating leases was 3.6 years and the weighted-average discount rate used to determine the operating lease liabilities was 6.6%.

Stockholders' Equity

3 Months Ended

Mar. 31, 2020

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 as of March 31, 2020 (in thousands):



Shares underlying outstanding warrants	705
Shares underlying outstanding stock options	6,684
Shares authorized for future equity award grants	2,961
Shares authorized for issuance pursuant to awards granted under the ESPP	1,692
	12,042

Common Stock Warrants

As of March 31, 2020, there were Series A warrants outstanding to purchase 415,200 shares of the Company’s common stock at an exercise price of $3.50 per share, which were issued in connection with a financing in October 2017, and which expire in October 2022. Also outstanding as of March 31, 2020, were warrants to purchase 193,788 shares of the Company’s common stock at an exercise price of $23.50 per share, which were issued in March 2017, and which expire in March 2027, and warrants to purchase 95,781 shares of the Company’s common stock at an exercise price of $73.73 per share, which were issued between August 2011 and August 2012, and which expire between August 2021 and August 2022. The Company issued 2,320 shares of its common stock upon the exercise of warrants during the three months ended March 31, 2020, and 18,285 shares of its common stock upon the exercise of warrants during the three months ended March 31, 2019.

Stock Plans

The Company issued 672,442 and 408,964 shares, respectively, of its common stock upon the exercise of stock options during the three months ended March 31, 2020 and 2019.

The ESPP enables eligible employees to purchase shares of the Company’s common stock using their after-tax payroll deductions, subject to certain conditions. 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. There were no shares of common stock purchased under the ESPP in the three months ended March 31, 2020 and 2019.

Stock-Based Compensation

The Company granted options to purchase 229,911 shares and 1,294,053 shares of common stock, respectively, under the 2013 Plan during the three months ended March 31, 2020 and 2019. These options have an exercise price equal to the closing price of the Company’s common stock on the applicable award date, and generally vest as to 25% of the underlying shares on the first anniversary of the award, with the balance of the options vesting monthly over the following three years.

In addition, during the three months ended March 31, 2019, the Company awarded stock options to purchase 1,035,000 shares of common stock, which were subject to and conditioned upon the approval by its stockholders of an increase in the number of shares of common stock reserved for issuance under our 2013 Plan prior to December 31, 2019. No stock-based compensation expense was recognized for these contingent stock option grants during the three months ended March 31, 2019, because the approval by our stockholders of the increase in the number of shares of common stock reserved for issuance under our 2013 Plan did not occur until June 2019.

The assumptions used in the Black-Scholes option-pricing model are as follows:



	Stock Options
	Three Months Ended March 31,
	2020		2019
Weighted average grant date fair value (per share)	$43.40		$32.51
Risk-free interest rate	1.1	%	2.5	%
Expected dividend yield	0.0	%	0.0	%
Expected volatility	72.5	%	71.6	%
Expected term (in years)	6.1		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 following table summarizes the allocation of stock-based compensation expense included in the consolidated statement of operations (in thousands):



	Three Months Ended March 31,
	2020		2019
Cost of sales	$	2,164	$	1,139
Selling, general & administrative	11,501		7,000
Research and development	2,200		1,695
Total	$	15,865	$	9,834

The total stock-based compensation expense capitalized as part of the cost of the Company’s inventories was $1.3 million and $1.3 million as of March 31, 2020 and December 31, 2019, respectively.

Income Taxes	3 Months Ended
Income Taxes	Mar. 31, 2020
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes For the three months ended March 31, 2020, the Company’s income tax expense is primarily attributable to state and foreign income tax expense as a result of current taxable income in those jurisdictions. The Company used the year-to-date effective tax rate method to determine its interim income tax expense for federal and state jurisdictions where a reliable estimate of the annual effective tax rate could not be made. The Company maintains a full valuation allowance against its net deferred tax assets as of March 31, 2020 based on the current assessment that it is not more likely than not these future benefits will be realized before expiration. On March 27, 2020, the United States enacted the Coronavirus Aid, Relief and Economic Security Act (CARES Act). The CARES Act is an emergency economic stimulus package that includes spending and tax breaks to strengthen the United States economy and fund a nationwide effort to curtail the effect of COVID-19. While the CARES Act provides sweeping tax changes in response to the COVID-19 pandemic, some of the more significant provisions which are expected to impact the Company’s financial statements include removal of certain limitations on utilization of net operating losses, increasing the loss carryback period for certain losses to five years, and increasing the ability to deduct interest expense, as well as amending certain provisions of the previously enacted Tax Cuts and Jobs Act. Due to the recent enactment of the CARES Act, the Company is unable to quantify the impact, if any, that the CARES Act will have on its financial position, results of operations or cash flows but it is not anticipated to be significant.

Commitments and Contingencies	3 Months Ended
Commitments and Contingencies	Mar. 31, 2020
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Legal and Regulatory Matters From time to time, the Company may be subject to legal proceedings or regulatory matters arising in the ordinary course of business, including actions with respect to intellectual property, employment, regulatory, product liability and contractual matters. In connection with these proceedings or matters, the Company regularly assesses the probability and amount (or range) of possible issues based on the developments in these proceedings or matters. A liability is recorded in the consolidated financial statements if it is determined that it is probable that a loss has been incurred, and that the amount (or range) of the loss can be reasonably estimated. Because of the uncertainties related to any pending proceedings or matters, the Company is currently unable to predict their ultimate outcome and, with respect to any legal proceeding or regulatory matter where no liability has been accrued, to make a reasonable estimate of the possible loss (or range of loss) that could result from an adverse outcome. As of March 31, 2020 and December 31, 2019, there were no 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 outcome, legal proceedings, regulatory matters, and other disputes and claims can have an adverse impact on the Company because of legal costs, diversion of management time and resources, and other factors.

Organization and Basis of Presentation (Policies)

3 Months Ended

Mar. 31, 2020

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Basis of Presentation

Basis of Presentation and Principles of Consolidation

The Company has prepared the accompanying unaudited condensed consolidated financial statements in accordance with accounting principles generally accepted in the United States of America (U.S. GAAP) for interim financial information and pursuant to the instructions to Form 10-Q and Article 10 of Regulation S-X. Accordingly, they do not include all of the information and disclosures required by U.S. GAAP for complete financial statements. In the opinion of management, all adjustments which are of a normal and recurring nature, considered necessary for a fair presentation of the financial information contained herein, have been included.

Interim financial results are not necessarily indicative of results anticipated for the full year or any other period(s). These unaudited condensed consolidated financial statements should be read in conjunction with the Company’s audited consolidated financial statements and accompanying notes included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2019 (Annual Report), from which the balance sheet information herein was derived.

The condensed consolidated financial statements include the accounts of Tandem Diabetes Care, Inc. and its wholly owned subsidiary in Canada. All significant intercompany balances and transactions have been eliminated in consolidation.

The functional currency of our foreign subsidiary is the local currency. The Company translates the financial statements of its foreign subsidiary 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 comprehensive loss and in accumulated other comprehensive income (loss) in the equity section of the Company’s condensed consolidated balance sheets. Foreign exchange gains or losses resulting from balances denominated in a currency other than the functional currency are recognized in interest and other income or interest and other expense in the Company’s condensed consolidated statements of operations.

Reclassification

Prior year amounts related to the presentation of proceeds from maturities and sales of short-term investments on the Company’s condensed consolidated statement of cash flows, have been reclassified to conform to the current year presentation.

Use of Estimates

Segment Reporting

Accounts Receivable

Fair Value of Financial Instruments

Operating Lease Right-of-Use Assets and Liabilities

Revenue Recognition

Revenue Recognition for Arrangements with Multiple Deliverables



	March 31, 2020		December 31, 2019
Deferred revenue	$	3,833	$	3,465
Other long-term liabilities	6,626		5,656
Total	$	10,459	$	9,121

Sales Returns

Warranty Reserve

Stock-Based Compensation

Net Loss Per Share

Recent Accounting Pronouncements

Summary of Significant Accounting Policies (Tables)

3 Months Ended

Mar. 31, 2020

Accounting Policies [Abstract]

Contract with Customer, Asset and Liability

Deferred revenue related to these performance obligations that are satisfied over time was included in the following consolidated balance sheet accounts in the amounts shown as of March 31, 2020 and December 31, 2019 (in thousands):



	March 31, 2020		December 31, 2019
Deferred revenue	$	3,833	$	3,465
Other long-term liabilities	6,626		5,656
Total	$	10,459	$	9,121

Summary of Reconciliation of Change in Product Warranty Liabilities

The following table provides a reconciliation of the change in product warranty liabilities from December 31, 2019 through March 31, 2020 (in thousands):



Balance at December 31, 2019	$	16,724
Provision for warranties issued during the period	4,814
Settlements made during the period	(3,390		)
Decreases in warranty estimates	(1,387		)
Balance at March 31, 2020	$	16,761



	March 31, 2020		December 31, 2019
Other current liabilities	$	6,427	$	4,707
Other long-term liabilities	10,334		12,017
Total warranty reserves	$	16,761	$	16,724

Schedule of Anti-Dilutive Securities



	Three Months Ended March 31,
	2020	2019
Warrants to purchase common stock	609	686
Options to purchase common stock	5,710	5,475
Awards granted under the ESPP	198	142
	6,517	6,303

Short-Term Investments (Tables)

3 Months Ended

Mar. 31, 2020

Investments, Debt and Equity Securities [Abstract]

Summary of Estimated Fair Value of Short-Term Investments

The following represents a summary of the estimated fair value of short-term investments as of March 31, 2020 and December 31, 2019 (in thousands):



At March 31, 2020	Maturity (in years)	Amortized Cost		Gross Unrealized Gain		Gross Unrealized Loss			Estimated Fair Value
Available-for-sale securities:
Commercial paper	Less than 1	$	17,352	$	11	$	—		$	17,363
U.S. Government-sponsored enterprise	Less than 2	20,255		63		—			20,318
U.S. Treasury securities	Less than 1	12,721		93		—			12,814
Corporate debt securities	Less than 2	35,251		39		(62		)	35,228
Total		$	85,579	$	206	$	(62	)	$	85,723



At December 31, 2019	Maturity (in years)	Amortized Cost		Gross Unrealized Gain		Gross Unrealized Loss			Estimated Fair Value
Available-for-sale securities:
Commercial paper	Less than 1	$	24,147	$	10	$	—		$	24,157
U.S. Government-sponsored enterprise	Less than 2	33,073		26		—			33,099
U.S. Treasury securities	Less than 2	17,963		17		(1		)	17,979
Corporate debt securities	Less than 2	50,011		42		(5		)	50,048
Total		$	125,194	$	95	$	(6	)	$	125,283

Accounts Receivable and Inventories (Tables)

3 Months Ended

Mar. 31, 2020

Accounts Receivable And Inventories Disclosure [Abstract]

Schedule of Accounts Receivable

Accounts receivable consisted of the following (in thousands):



	March 31,			December 31,
	2020			2019
Accounts receivable	$	57,346		$	49,889
Less allowance for credit losses	(3,384		)	(3,304		)
Accounts receivable, net	$	53,962		$	46,585

Accounts Receivable, Allowance for Credit Loss



	For the Three Months Ended
	March 31, 2020			March 31, 2019
Balance at beginning of the period	$	3,304		$	1,837
Provision for expected credit losses	862			342
Write-offs and adjustments, net of recoveries	(782		)	(163		)
Balance at end of the period	$	3,384		$	2,016

Summary of Inventories

Inventories consisted of the following as of March 31, 2020 and December 31, 2019 (in thousands):



	March 31, 2020		December 31, 2019
Raw materials	$	31,795	$	20,699
Work-in-process	14,543		16,532
Finished goods	14,131		11,842
Inventories	$	60,469	$	49,073

Fair Value Measurements (Tables)

3 Months Ended

Mar. 31, 2020

Fair Value Disclosures [Abstract]

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



			Fair Value Measurements at March 31, 2020
			(Level 1)		(Level 2)		(Level 3)
Assets
Cash equivalents⁽¹⁾	$	69,346	$	69,346	$	—	$	—
Commercial paper	17,363		—		17,363		—
U.S. Government-sponsored enterprise	20,318		—		20,318		—
U.S. Treasury securities	12,814		12,814		—		—
Corporate debt securities	35,228		—		35,228		—
Total assets	$	155,069	$	82,160	$	72,909	$	—

Liabilities
Common stock warrants	$	25,290	$	—	$	—	$	25,290
Total liabilities	$	25,290	$	—	$	—	$	25,290



			Fair Value Measurements at December 31, 2019
			(Level 1)		(Level 2)		(Level 3)
Assets
Cash equivalents⁽¹⁾	$	49,077	$	49,077	$	—	$	—
Commercial paper	24,157		—		24,157		—
U.S. Government-sponsored enterprise	33,099		—		33,099		—
U.S. Treasury securities	17,979		17,979		—		—
Corporate debt securities	50,048		—		50,048		—
Total assets	$	174,360	$	67,056	$	107,304	$	—

Liabilities
Common stock warrants	$	23,509	$	—	$	—	$	23,509
Total liabilities	$	23,509	$	—	$	—	$	23,509

(1)

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

Schedule of Assumptions Used to Estimate Fair Values of Common Stock Warrants

The assumptions used to estimate the fair values of the outstanding Series A warrants at March 31, 2020 and December 31, 2019 are presented below:



	March 31, 2020		December 31, 2019
Risk-free interest rate	0.3	%	1.6	%
Expected dividend yield	0.0	%	0.0	%
Expected volatility	74.9	%	77.2	%
Expected term (in years)	2.5		2.8

Summary of Changes in Fair Value of Total Level 3 Financial Assets

The following table presents a summary of changes in the fair value of the Company’s Level 3 financial liabilities for the three months ended March 31, 2020 and 2019:



	Three Months Ended March 31,
	2020			2019
Balance at beginning of the period	$	23,509		$	17,926
Loss recognized from the change in fair value of common stock warrants	1,922			12,746
Decrease in fair value from warrants exercised during the period	(141		)	(910		)
Balance at end of the period	$	25,290		$	29,762

Leases Leases (Tables)

3 Months Ended

Mar. 31, 2020

Leases [Abstract]

Schedule of Future Minimum Payments Under Non-cancellable Operating Leases

Maturities of operating lease liabilities at March 31, 2020 were as follows (in thousands):



Years Ending December 31,
2020 (remaining)	$	5,994
2021	9,422
2022	7,314
2023	3,388
2024	1,881
Thereafter	3,975
Total undiscounted lease payments	31,974
Less: amount representing interest	(4,107		)
Present value of operating lease liabilities	27,867
Less: current portion of operating lease liabilities	(8,320		)
Operating lease liabilities - long-term	$	19,547

Stockholders' Equity (Tables)

3 Months Ended

Mar. 31, 2020

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 as of March 31, 2020 (in thousands):



Shares underlying outstanding warrants	705
Shares underlying outstanding stock options	6,684
Shares authorized for future equity award grants	2,961
Shares authorized for issuance pursuant to awards granted under the ESPP	1,692
	12,042

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

The assumptions used in the Black-Scholes option-pricing model are as follows:



	Stock Options
	Three Months Ended March 31,
	2020		2019
Weighted average grant date fair value (per share)	$43.40		$32.51
Risk-free interest rate	1.1	%	2.5	%
Expected dividend yield	0.0	%	0.0	%
Expected volatility	72.5	%	71.6	%
Expected term (in years)	6.1		6.1

Summary for Allocation of Stock-Based Compensation Expense

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



	Three Months Ended March 31,
	2020		2019
Cost of sales	$	2,164	$	1,139
Selling, general & administrative	11,501		7,000
Research and development	2,200		1,695
Total	$	15,865	$	9,834

Organization and Basis of Presentation - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Organization And Basis Of Presentation [Line Items]
Cash and cash equivalents and short-term investments	$ 160,200
Accumulated deficit	(639,695)		$ (624,828)
Net loss	$ (14,867)	$ (22,992)
Insulin Pump \| Minimum
Organization And Basis Of Presentation [Line Items]
Expected life span term	4 years

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

+ References + Details

Summary of Significant Accounting Policies - Additional Information (Detail) $ in Thousands	3 Months Ended
	Mar. 31, 2020 USD ($) segment	Dec. 31, 2019 USD ($)
Summary Of Significant Accounting Policies [Line Items]
Number of operating segments \| segment	1
Offered period for sales return	30 days
Allowance for product returns	$ 500	$ 400
Warranty reserve	16,761	$ 16,724
Warranty reserves
Summary Of Significant Accounting Policies [Line Items]
Warranty reserve	$ 16,761
Complementary products
Summary Of Significant Accounting Policies [Line Items]
Warranty period offered	4 years
Tandem 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

Summary of Significant Accounting Policies - Summary of Reconciliation of Change in Product Warranty Liabilities (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2020	Dec. 31, 2019
Movement in Standard and Extended Product Warranty Accrual, Increase (Decrease) [Roll Forward]
Beginning balance	$ 16,724
Provision for warranties issued during the period	4,814
Settlements made during the period	(3,390)
Decreases in warranty estimates	(1,387)
Ending balance	16,761
Other current liabilities		$ 6,427	$ 4,707
Other long-term liabilities		10,334	12,017
Total warranty reserves	$ 16,724	$ 16,761	$ 16,724

Summary of Significant Accounting Policies - Schedule of Anti-Dilutive Securities (Detail) - shares shares in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share, amount	6,517	6,303
ESPP
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share, amount	198	142
Common stock warrants
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share, amount	609	686
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	5,710	5,475

Summary of Significant Accounting Policies - Deferred Revenue Related to Performance Obligations (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Disaggregation of Revenue [Line Items]
Deferred revenue	$ 4,377	$ 3,869
Transferred over Time
Disaggregation of Revenue [Line Items]
Deferred revenue	3,833	3,465
Other long-term liabilities	6,626	5,656
Total	$ 10,459	$ 9,121

Short-Term Investments - Summary of Estimated Fair Value of Short-Term Investments (Detail) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2020	Dec. 31, 2019
Cash Cash Equivalents And Short Term Investments [Line Items]
Amortized Cost	$ 85,579	$ 125,194
Gross Unrealized Gain	206	95
Gross Unrealized Loss	(62)	(6)
Estimated Fair Value	85,723	125,283
Commercial paper
Cash Cash Equivalents And Short Term Investments [Line Items]
Amortized Cost	17,352	24,147
Gross Unrealized Gain	11	10
Gross Unrealized Loss	0	0
Estimated Fair Value	$ 17,363	$ 24,157
Commercial paper \| Maximum
Cash Cash Equivalents And Short Term Investments [Line Items]
Available-for-sale securities, Maturity (in years)	1 year	1 year
U.S. Government-sponsored enterprise
Cash Cash Equivalents And Short Term Investments [Line Items]
Amortized Cost	$ 20,255	$ 33,073
Gross Unrealized Gain	63	26
Gross Unrealized Loss	0	0
Estimated Fair Value	$ 20,318	$ 33,099
U.S. Government-sponsored enterprise \| Maximum
Cash Cash Equivalents And Short Term Investments [Line Items]
Available-for-sale securities, Maturity (in years)	2 years	2 years
U.S. Treasury securities
Cash Cash Equivalents And Short Term Investments [Line Items]
Amortized Cost	$ 12,721	$ 17,963
Gross Unrealized Gain	93	17
Gross Unrealized Loss	0	(1)
Estimated Fair Value	$ 12,814	$ 17,979
U.S. Treasury securities \| Maximum
Cash Cash Equivalents And Short Term Investments [Line Items]
Available-for-sale securities, Maturity (in years)	1 year	2 years
Corporate debt securities
Cash Cash Equivalents And Short Term Investments [Line Items]
Amortized Cost	$ 35,251	$ 50,011
Gross Unrealized Gain	39	42
Gross Unrealized Loss	(62)	(5)
Estimated Fair Value	$ 35,228	$ 50,048
Corporate debt securities \| Maximum
Cash Cash Equivalents And Short Term Investments [Line Items]
Available-for-sale securities, Maturity (in years)	2 years	2 years

Accounts Receivable and Inventories - Summary of Accounts Receivable (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019	Mar. 31, 2019	Dec. 31, 2018
Accounts Receivable And Inventories Disclosure [Abstract]
Accounts receivable	$ 57,346	$ 49,889
Less allowance for credit losses	(3,384)	(3,304)	$ (2,016)	$ (1,837)
Accounts receivable, net	$ 53,962	$ 46,585

Accounts Receivable and Inventories - Allowance For Credit Losses (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Allowance for Doubtful Accounts Receivable [Roll Forward]
Balance at beginning of the period	$ 3,304	$ 1,837
Provision for expected credit losses	862	342
Write-offs and adjustments, net of recoveries	(782)	(163)
Balance at end of the period	$ 3,384	$ 2,016

Accounts Receivable and Inventories - Summary of Inventories (Detail) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Accounts Receivable And Inventories Disclosure [Abstract]
Raw materials	$ 31,795	$ 20,699
Work-in-process	14,543	16,532
Finished goods	14,131	11,842
Inventories	$ 60,469	$ 49,073

Fair Value Measurements - Schedule of Financial Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) - Fair Value, Measurements, Recurring - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total assets	$ 155,069	$ 174,360
Total liabilities	25,290	23,509
Common stock warrants
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total liabilities	25,290	23,509
(Level 1)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total assets	82,160	67,056
Total liabilities	0	0
(Level 1) \| Common stock warrants
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total liabilities	0	0
(Level 2)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total assets	72,909	107,304
Total liabilities	0	0
(Level 2) \| Common stock warrants
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total liabilities	0	0
(Level 3)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total assets	0	0
Total liabilities	25,290	23,509
(Level 3) \| Common stock warrants
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total liabilities	25,290	23,509
Cash equivalents
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total assets	69,346	49,077
Cash equivalents \| (Level 1)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total assets	69,346	49,077
Cash equivalents \| (Level 2)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total assets	0	0
Cash equivalents \| (Level 3)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total assets	0	0
Commercial paper
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total assets	17,363	24,157
Commercial paper \| (Level 1)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total assets	0	0
Commercial paper \| (Level 2)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total assets	17,363	24,157
Commercial paper \| (Level 3)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total assets	0	0
U.S. Government-sponsored enterprise
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total assets	20,318	33,099
U.S. Government-sponsored enterprise \| (Level 1)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total assets	0	0
U.S. Government-sponsored enterprise \| (Level 2)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total assets	20,318	33,099
U.S. Government-sponsored enterprise \| (Level 3)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total assets	0	0
U.S. Treasury securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total assets	12,814	17,979
U.S. Treasury securities \| (Level 1)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total assets	12,814	17,979
U.S. Treasury securities \| (Level 2)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total assets	0	0
U.S. Treasury securities \| (Level 3)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total assets	0	0
Corporate debt securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total assets	35,228	50,048
Corporate debt securities \| (Level 1)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total assets	0	0
Corporate debt securities \| (Level 2)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total assets	35,228	50,048
Corporate debt securities \| (Level 3)
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Total assets	$ 0	$ 0

Fair Value Measurements - Schedule of Financial Assets and Liabilities Measured at Fair Value on Recurring Basis Footnote (Detail)	3 Months Ended
	Mar. 31, 2020
Maximum
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash equivalents maturity term	3 months

Fair Value Measurements - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019	Oct. 31, 2017
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loss recognized from change in fair value of common stock warrants	$ 1,922	$ 12,746
Series A warrants
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Warrants issue to purchase common stock (in shares)	2,115	18,285
Warrants exercise price (USD per share)	$ 3.50
Warrants initial value				$ 5,200
Loss recognized from change in fair value of common stock warrants	$ 1,900	$ 12,500
Outstanding warrants (in shares)	415,200	492,500
Series A warrants \| Secondary Public Offering
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Public offering period	5 years		5 years
Warrants issue to purchase common stock (in shares)	4,630,000		4,630,000
Warrants exercise price (USD per share)	$ 3.50		$ 3.50

Fair Value Measurements - Schedule of Assumptions Used to Estimate Fair Values of Common Stock Warrants (Detail) - Series A warrants	Mar. 31, 2020	Dec. 31, 2019
Risk-free interest rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Assumptions used to estimate fair value of common stock warrants	0.003	0.016
Expected dividend yield
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Assumptions used to estimate fair value of common stock warrants	0.000	0.000
Expected volatility
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Assumptions used to estimate fair value of common stock warrants	0.749	0.772
Expected Term
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Expected term (in years)	2 years 6 months	2 years 9 months 18 days

Fair Value Measurements - Summary of Changes in Fair Value of Total Level 3 Financial Assets (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Fair Value Disclosures [Abstract]
Balance at beginning of period	$ 23,509	$ 17,926
Loss recognized from the change in fair value of common stock warrants	1,922	12,746
Decrease in fair value from warrants exercised during the period	(141)	(910)
Balance at end of period	$ 25,290	$ 29,762

Leases - Additional Information (Detail) $ in Thousands	3 Months Ended
Leases - Additional Information (Detail) $ in Thousands	Mar. 31, 2020 USD ($)	Mar. 31, 2019 USD ($)	Jan. 31, 2020 USD ($) ft²	Dec. 31, 2019 USD ($)	Nov. 30, 2019 USD ($) ft²	May 31, 2019 ft²	Jan. 31, 2019 ft²	Jan. 01, 2019 USD ($)
Lessee, Lease, Description [Line Items]
Operating lease, liability	$ 27,867
Operating lease right-of-use assets	23,014			$ 15,561
Future minimum lease payments	31,974
Lease cost	1,800	$ 700
Operating lease, cost	1,700	700
Short-term lease, cost	100
Operating lease, payments	$ 1,600	900
Operating lease, weighted average remaining lease term	4 years 1 month 6 days			3 years 7 months 6 days
Operating lease, weighted average discount rate, percent	6.30%			6.60%
10935 Vista Sorrento Parkway, San Diego, California
Lessee, Lease, Description [Line Items]
Operating lease, liability		3,100
Operating lease right-of-use assets		3,100
Area of office space leased \| ft²						33,681	25,332
10935 Vista Sorrento Parkway, San Diego, California \| Maximum
Lessee, Lease, Description [Line Items]
Operating lease extension period	4 years
Shoreline Drive, Boise, Idaho
Lessee, Lease, Description [Line Items]
Operating lease, liability	$ 6,500
Operating lease right-of-use assets					$ 6,500
Area of office space leased \| ft²					94,562
Term of contract					84 months
Operating lease extension period					3 years
Future minimum lease payments	8,200
High Bluff Drive, San Diego, California
Lessee, Lease, Description [Line Items]
Operating lease, liability	2,300
Operating lease right-of-use assets			$ 2,300
Area of office space leased \| ft²			30,703
Future minimum lease payments	$ 2,400
Accounting Standards Update 2016-02
Lessee, Lease, Description [Line Items]
Operating lease, liability								$ 12,400
Operating lease right-of-use assets								12,400
Accounting Standards Update 2016-02 \| Difference Between Leases Guidance in Effect Before and After Topic 842
Lessee, Lease, Description [Line Items]
Deferred rent—long-term								(3,800)
Accounting Standards Update 2016-02 \| Difference Between Leases Guidance in Effect Before and After Topic 842 \| Other Current Liabilities
Lessee, Lease, Description [Line Items]
Deferred rent, current								$ (1,000)
Vista Sorrento Original Lease \| 10935 Vista Sorrento Parkway, San Diego, California
Lessee, Lease, Description [Line Items]
Operating lease, liability		4,700
Operating lease right-of-use assets		$ 4,700

Leases Schedule of Future Minimum Payments Under Non-cancellable Operating Leases (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Leases [Abstract]
2020 (remaining)	$ 5,994
2021	9,422
2022	7,314
2023	3,388
2024	1,881
Thereafter	3,975
Total undiscounted lease payments	31,974
Less: amount representing interest	(4,107)
Present value of operating lease liabilities	27,867
Less: current portion of operating lease liabilities	(8,320)	$ (6,320)
Operating lease liabilities - long-term	$ 19,547	$ 14,063

Stockholders' Equity - Schedule of Shares of Common Stock Reserved for Future Issuance (Detail) shares in Thousands	Mar. 31, 2020 shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved for future issuance (in shares)	12,042
Shares underlying outstanding warrants
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved for future issuance (in shares)	705
Shares underlying outstanding stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved for future issuance (in shares)	6,684
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)	2,961
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)	1,692

Stockholders' Equity - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Millions	1 Months Ended	3 Months Ended		12 Months Ended
	Jun. 30, 2019	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019	Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation expense capitalized as part of cost of inventory		$ 1.3			$ 1.3
2013 Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares granted (in shares)		229,911	1,294,053
Options to purchase common stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock shares issued (in shares)		672,442	408,964
Contingent stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares granted (in shares)			1,035,000
Common stock warrants
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock shares issued (in shares)		2,320	18,285
ESPP
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Offering period		2 years
Purchase period		Four Six-Month
Purchase of common stock under ESPP (in shares)		0	0
First anniversary \| 2013 Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting percentage	25.00%
Monthly vesting over following 3 years \| 2013 Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting percentage		75.00%		75.00%
Series A warrants
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Outstanding warrants (in shares)		415,200	492,500
Warrants exercise price (USD per share)		$ 3.50
Common Stock Warrant Expiring March 2027
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Outstanding warrants (in shares)		193,788
Warrants exercise price (USD per share)		$ 23.50
Common Stock Warrant Expiring Between August 2021 and August 2022
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Outstanding warrants (in shares)		95,781
Warrants exercise price (USD per share)		$ 73.73

Stockholders' Equity - Schedule of Assumptions Used in Black-Scholes Option-Pricing Model (Detail) - Stock Options - $ / shares	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average grant date fair value (in usd per share)	$ 43.40	$ 32.51
Risk-free interest rate	1.10%	2.50%
Expected dividend yield	0.00%	0.00%
Expected volatility	72.50%	71.60%
Expected term (in years)	6 years 1 month 6 days	6 years 1 month 6 days

Stockholders' Equity - Summary for Allocation of Stock-Based Compensation Expense (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation cost	$ 15,865	$ 9,834
Cost of sales
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation cost	2,164	1,139
Selling, general & administrative
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation cost	11,501	7,000
Research and development
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation cost	$ 2,200	$ 1,695

Commitments and Contingencies - Additional Information (Detail) - legal_matter	3 Months Ended	12 Months Ended
	Mar. 31, 2020	Dec. 31, 2019
Commitments and Contingencies Disclosure [Abstract]
Number of legal proceedings, regulatory matters, or other, disputes or claims	0	0