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Document and Entity Information - USD ($) $ in Millions	12 Months Ended
Document and Entity Information - USD ($) $ in Millions	Dec. 31, 2014	Feb. 20, 2015	Jun. 30, 2014
Document And Entity Information [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2014
Document Fiscal Year Focus	2014
Document Fiscal Period Focus	FY
Trading Symbol	TNDM
Entity Registrant Name	TANDEM DIABETES CARE INC
Entity Central Index Key	0001438133
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	No
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Filer Category	Accelerated Filer
Entity Common Stock, Shares Outstanding		23,714,990
Entity Public Float			$ 180

Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2014	Dec. 31, 2013
Current assets:
Cash and cash equivalents	$ 31,176	$ 124,385
Restricted cash	2,000	2,050
Short-term investments	36,106	5,095
Accounts receivable, net	7,652	5,299
Inventory, net	11,913	10,330
Prepaid and other current assets	1,904	1,830
Total current assets	90,751	148,989
Property and equipment, net	12,581	9,886
Other long-term assets	691	643
Total assets	106,464	162,215
Current liabilities:
Accounts payable	1,949	2,352
Accrued expense	2,920	1,874
Employee-related liabilities	9,722	5,876
Deferred revenue	840	411
Other current liabilities	2,663	4,086
Total current liabilities	18,094	14,599
Notes payable—long-term	29,440	29,397
Deferred rent—long-term	2,700	1,887
Other long-term liabilities	1,658	795
Total liabilities	51,892	46,678
Commitments and contingencies (Note 11)
Stockholders’ equity:
Preferred stock, $0.001 par value, 5,000 shares authorized at December 31, 2014, and 2013, no shares issued and outstanding at December 31, 2014, and 2013 respectively.
Common stock, $0.001 par value; 100,000 shares authorized as of December 31, 2014 and 2013, respectively, 23,655 and 22,926 shares issued and outstanding at December 31, 2014 and 2013, respectively.	24	23
Additional paid-in capital	303,255	284,705
Accumulated other comprehensive income	8
Accumulated deficit	(248,715)	(169,191)
Total stockholders’ equity	54,572	115,537
Total liabilities and stockholders’ equity	106,464	162,215
Patents [Member]
Current assets:
Patents, net	$ 2,441	$ 2,697

Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 2014	Dec. 31, 2013
Statement Of Financial Position [Abstract]
Preferred stock, par value	$ 0.001	$ 0.001
Preferred stock, shares authorized	5,000,000	5,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value	$ 0.001	$ 0.001
Common stock, shares authorized	100,000,000	100,000,000
Common stock, shares issued	23,655,000	23,655,000
Common stock, shares outstanding	22,926,000	22,926,000

Statements of Operations and Comprehensive Loss - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Income Statement [Abstract]
Sales	$ 49,722	$ 29,007	$ 2,475
Cost of sales	34,474	22,840	3,823
Gross profit (loss)	15,248	6,167	(1,348)
Operating expenses:
Selling, general and administrative	75,121	44,522	22,691
Research and development	15,791	11,079	9,009
Total operating expenses	90,912	55,601	31,700
Operating loss	(75,664)	(49,434)	(33,048)
Other income (expense), net
Interest and other income	112	7	2
Interest and other expense	(3,901)	(4,710)	(2,525)
Change in fair value of stock warrants	0	(9,002)	2,556
Total other income (expense), net	(3,789)	(13,705)	33
Loss before taxes	(79,453)	(63,139)	(33,015)
Provision for income tax expense	71
Net loss	(79,524)	(63,139)	(33,015)
Other comprehensive loss:
Unrealized gain on short-term investments	8
Comprehensive loss	$ (79,516)	$ (63,139)	$ (33,015)
Net loss per share, basic and diluted	$ (3.42)	$ (21.46)	$ (175.88)
Weighted average shares used to compute basic and diluted net loss per share	23,272	2,942	188

Statements of Convertible Preferred Stock and Stockholders' Equity (Deficit) - USD ($) $ in Thousands	Total	Convertible Preferred Stock [Member]	Common Stock [Member]	Additional Paid-in Capital [Member]	Accumulated Other Comprehensive Income [Member]	Accumulated Deficit [Member]	Series D Preferred Stock [Member] Convertible Preferred Stock [Member]
Balance at Dec. 31, 2011	$ (71,295)	$ 67,930		$ 1,435		$ (72,730)
Balance, Shares at Dec. 31, 2011		1,688,000	212,000
Issuance of stock							$ 30,867
Issuance of stock, Shares							7,035,000
Conversion of preferred stock							$ 26,391
Conversion of preferred stock, Shares							5,997,000
Vesting of restricted common stock and change in fair value of unvested restricted stock subject to repurchase	248			248
Exercise of stock options	35			35
Exercise of stock options, Shares			3,000
Conversion of Series A, Series B, and Series C preferred stock into common stock	550	$ (550)		550
Conversion of Series A, Series B, and Series C preferred stock into common stock, Shares		(23,000)	14,000
Stock-based compensation	246			246
Repurchase and retirement of common stock	(50)			(1)		(49)
Repurchase and retirement of common stock, Shares			(2,000)
Loss on extinguishment of convertible notes payable	(2,771)			(2,513)		(258)
Net loss	(33,015)					(33,015)
Balance at Dec. 31, 2012	(106,052)	$ 124,638				(106,052)
Balance, Shares at Dec. 31, 2012		14,697,000	227,000
Issuance of stock							$ 15,991
Issuance of stock, Shares							3,656,000
Issuance of common stock warrants in connection with term loan	437			437
Exercise of preferred stock warrants		$ 3,629
Exercise of preferred stock warrants, Shares		428,000
Issuance of common stock in initial public offering, net of underwriter’s discount and offering costs, value	125,039		$ 9	125,030
Issuance of common stock in initial public offering, net of underwriter’s discount and offering costs, shares			9,200,000
Conversion of preferred stock in connection with initial public offering, value	144,258	$ (144,258)	$ 13	144,245
Conversion of preferred stock in connection with initial public offering, shares		(18,781,000)	13,404,000
Vesting of restricted common stock and change in fair value of unvested restricted stock subject to repurchase	33			33
Conversion of preferred stock warrants into common stock warrants	9,550			9,550
Exercise of common stock warrants	628		$ 1	627
Exercise of common stock warrants, Shares			85,000
Exercise of stock options	$ 66			66
Exercise of stock options, Shares	9,913		10,000
Stock-based compensation	$ 4,717			4,717
Net loss	(63,139)					(63,139)
Balance at Dec. 31, 2013	115,537		$ 23	284,705		(169,191)
Balance, Shares at Dec. 31, 2013			22,926,000
Exercise of common stock warrants	138		$ 1	137
Exercise of common stock warrants, Shares			334,000
Exercise of stock options	$ 325			325
Exercise of stock options, Shares	143,779		144,000
Issuance of common stock for Employee Stock Purchase Plan	$ 3,168			3,168
Issuance of common stock for Employee Stock Purchase Plan, Shares			251,000
Stock-based compensation	14,920			14,920
Unrealized gain on short-term investments	8				$ 8
Net loss	(79,524)					(79,524)
Balance at Dec. 31, 2014	$ 54,572		$ 24	$ 303,255	$ 8	$ (248,715)
Balance, Shares at Dec. 31, 2014			23,655,000

Statements of Convertible Preferred Stock and Stockholders' Equity (Deficit) (Parenthetical) - Series D Preferred Stock [Member] - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012
Issuance of Series D convertible preferred stock, price per share	$ 4.40	$ 4.40
Issuance of Series D convertible preferred stock, issuance costs	$ 95	$ 90
Conversion of convertible notes payable and accrued interest into Series D convertible preferred stock, conversion price per share		$ 4.40

Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
Statements of Cash Flows - USD ($) $ in Thousands	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Operating activities
Net loss	$ (79,524)	$ (63,139)	$ (33,015)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization expense	4,389	3,167	2,032
Accretion of discount on notes payable and convertible notes			1,209
Interest expense related to amortization of debt discount and debt issuance costs	219	595	836
Provision for allowance for doubtful accounts	188	275	46
Provision for inventory reserve	163	815	335
Change in fair value of common and preferred stock warrants	0	9,002	(2,556)
Amortization of premium/discount on short-term investments	(53)
Stock-based compensation expense	14,995	4,456	246
Other	41	62	57
Changes in operating assets and liabilities:
Accounts receivable	(2,541)	(3,161)	(2,458)
Inventory	(1,820)	(4,625)	(6,596)
Prepaid and other current assets	(82)	106	(1,054)
Other long-term assets	(150)	(85)
Accounts payable	(1,225)	859	1,383
Accrued expense	973	342	918
Employee-related liabilities	3,846	3,885	979
Deferred revenue	429	(1,472)	1,884
Other current liabilities	(1,575)	895	2,342
Deferred rent	(461)	(522)	(234)
Other long-term liabilities	810	763
Payments received on note receivable from employees		25	175
Net cash used in operating activities	(61,378)	(47,757)	(33,471)
Investing activities
Purchase of short-term investments	(67,101)	(5,095)
Proceeds from sales and maturities of short-term investments	36,210
Purchase of property and equipment	(4,406)	(4,010)	(4,529)
Purchase of patents	(173)	(2,000)	(1,000)
Net cash used in investing activities	(35,470)	(11,105)	(5,529)
Financing activities
Issuance of convertible notes payable			12,208
Issuance of notes payable, net of issuance costs	29,925	28,874	5,000
Restricted cash in connection with notes payable and corporate credit card	50	(2,000)
Principal payments on notes payable	(30,000)	(4,396)	(604)
Proceeds from issuance of preferred stock for cash, net of offering costs		15,991	30,867
Proceeds from initial public offering, net of offering costs		125,040
Proceeds from issuance of common stock	3,664	2,575	35
Net cash provided by financing activities	3,639	166,084	47,506
Net increase (decrease) in cash and cash equivalents	(93,209)	107,222	8,506
Cash and cash equivalents at beginning of period	124,385	17,163	8,657
Cash and cash equivalents at end of period	31,176	124,385	17,163
Supplemental disclosures of cash flow information
Interest paid	3,369	4,115	297
Income taxes paid	71	19	3
Supplemental schedule of noncash investing and financing activities
Lease incentive—lessor-paid tenant improvements	1,604		2,018
Loss on extinguishment of debt			2,770
Common and preferred stock warrants issued, including incremental value of modification of warrants		437	3,815
Property and equipment included in accounts payable	789		200
Patent included in accrued expense	$ 74
Conversion of preferred stock warrants into common stock warrants		9,550
Conversion of convertible preferred stock into common stock		$ 144,258
Series D Preferred Stock [Member]
Supplemental schedule of noncash investing and financing activities
Conversion of notes payable and accrued interest for Series D convertible preferred stock			$ 26,391

Organization and Basis of Presentation	12 Months Ended
Organization and Basis of Presentation	Dec. 31, 2014
Accounting Policies [Abstract]
Organization and Basis of Presentation	1. Organization and Basis of Presentation The Company Tandem Diabetes Care, Inc. is a medical device company focused on the design, development and commercialization of products for people with insulin-dependent diabetes. Unless the context requires otherwise, the terms the “Company” or “Tandem” refer to Tandem Diabetes Care, Inc. The Company designed and commercialized its flagship product, the t:slim Insulin Delivery System, or t:slim, based on its proprietary technology platform and unique consumer-focused approach. The U.S. Food and Drug Administration (FDA) cleared t:slim in November 2011 and the Company commenced commercial sales of t:slim in the United States in August 2012. In January 2015, the Company received clearance from the FDA, to commercialize its next product, the t:flex Insulin Delivery System, or t:flex, for people with greater insulin needs. The Company intends to begin commercial sales of t:flex in the United States during the second quarter of 2015. Tandem was originally incorporated in the state of Colorado on January 27, 2006 under the name Phluid Inc. On January 7, 2008, the Company was re-incorporated in the state of Delaware for the purposes of changing its legal name from Phluid Inc. to Tandem Diabetes Care, Inc. and changing its state of incorporation from Colorado to Delaware. The Company has incurred operating losses since its inception and had an accumulated deficit of $248.7 million at December 31, 2014. The Company’s ability to achieve profitable operations primarily depends upon achieving a level of revenues adequate to support its cost structure. The Company has relied on its ability to fund its operations through private and public equity and debt financing. Management expects operating losses and negative cash flows to continue for the foreseeable future. The Company may elect to finance future operations using its existing term loan agreements or may pursue equity or debt financing through other sources. If necessary financing is not obtained or achieved, the Company will likely be required to reduce its current planned increases in expenditures, which could have an adverse impact on its ability to achieve its intended business objectives. There can be no assurance that equity or debt financing, beyond what is available under its existing term loan agreements, will be available on acceptable terms, or at all. Any equity financing may result in dilution to existing shareholders holders and any additional debt financing may include restrictive covenants. Initial Public Offering In November 2013, the Company completed its initial public offering of 8,000,000 shares of its common stock at a public offering price of $15.00 per share. Net cash proceeds from the initial public offering were approximately $108.3 million, after deducting underwriting discounts, commissions and estimated offering related transaction costs payable by the Company. In November 2013, the underwriters also exercised their overallotment option and purchased an additional 1,200,000 shares of the Company’s common stock, from which the Company received cash proceeds, net of underwriting discounts and commissions, of approximately $16.7 million. In connection with the closing of the initial public offering, all of the Company’s shares of convertible preferred stock outstanding at the time of the offering were automatically converted into 13,403,747 shares of common stock. In addition, all outstanding preferred stock warrants were automatically converted into warrants to purchase an aggregate 1,171,352 shares of our common stock (see Note 4, “Fair Value Measurements”). Basis of Presentation The accompanying financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America, or GAAP. Reverse Stock Splits In October 2013, the Board of Directors approved a 1-for-1.6756 reverse stock split of the Company’s common stock. All share and per share information included in the accompanying financial statements and notes to the financial statements give retroactive effect to this reverse stock split for the Company’s common stock. Voluntary Recall On January 10, 2014, the Company announced a voluntary recall of select lots of cartridges used with t:slim that may have been at risk of leaking. The cause of the recall was identified during the Company’s internal product testing. The recall was expanded on January 20, 2014 to include additional lots of affected cartridges used with t:slim. The Company incurred approximately $1.7 million in direct costs associated with the recall. The Company recorded a cost of sales charge of approximately $1.3 million in the fourth quarter of 2013 and recorded a cost of sales charge for the remainder in the first quarter of 2014 for affected cartridges shipped in 2014. The total cost of the recall consisted of approximately $0.7 million associated with the return and replacement of affected cartridges in the field and approximately $1.0 million for the write-off of affected cartridges within the Company’s internal inventory. As of December 31, 2014, the FDA has determined that the recall is terminated and the Company does not currently expect any further direct financial impact of the recall beyond these costs.

Summary of Significant Accounting Policies

12 Months Ended

Dec. 31, 2014

Accounting Policies [Abstract]

Summary of Significant Accounting Policies

2. Summary of Significant Accounting Policies

Use of Estimates

The preparation of the financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets, liabilities, revenues and expenses, and the disclosure of contingent assets and liabilities in our financial statements and accompanying notes as of the date of the financial statements. Actual results could differ from those estimates and assumptions.

Segment Reporting

Operating segments are identified as components of an enterprise about which segment discrete financial information is available for evaluation by the chief operating decision-maker in making decisions regarding resource allocation and assessing performance. To date, we have viewed our operations and managed our business as one segment operating in the United States.

Cash and Cash Equivalents

The Company considers all highly liquid investments with a maturity of three months or less from the date of purchase to be cash equivalents.

Short-Term Investments

Based on the nature of the assets, the Company’s short-term investment are classified as either available-for-sale or trading 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, net of tax, are reported as a component of other comprehensive gain (loss) within the statements of operations and comprehensive gain (loss) as a separate component of stockholders’ equity (deficit). Unrealized gains or losses on trading securities are reported in interest income. At December 31, 2014 and 2013, the Company had no investments that were classified as held-to-maturity. The Company determines the realized gains or losses of available-for-sale securities using the specific identification method and includes net realized gains and losses in interest income. The Company periodically reviews available-for-sale securities for other than temporary declines in fair value below the cost basis whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable.

Restricted Cash

Restricted cash as of December 31, 2014 and 2013 was primarily composed of a $2.0 million minimum cash balance requirement in connection with the Capital Royalty Term Loan (see Note 6, “Loan and Warrant Agreements).

Accounts Receivable

We grant credit to various customers in the normal course of business. We maintain an allowance for doubtful accounts for potential credit losses. Generally, receivables greater than 120 days past due are deemed uncollectible. 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 customers who accounted for 10% or more of net accounts receivable:

	December 31,
	2014			2013
Byram Healthcare		19.2	%		N/A
Edgepark Medical Supplies, Inc.		12.3	%		13.1	%
CCS Medical, Inc.		N/A			21.4	%

The following table summarizes customers who accounted for 10% or more of sales for the periods presented:

	December 31,
	2014			2013			2012
Edgepark Medical Supplies, Inc.		16.0	%		16.1	%		19.3	%
CCS Medical, Inc.		11.6	%		13.6	%	N/A
Byram Healthcare		10.9	%	N/A			N/A
Solara Medical Supplies, Inc.	N/A			N/A				15.7	%

Fair Value of Financial Instruments

The carrying amounts of cash and cash equivalents, accounts receivable, accounts payable, accrued expense, 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. Based on the borrowing rates currently available for loans with similar terms, the Company believes that the fair value of its long-term debt approximates its carrying value.

Inventory

Inventories are valued at the lower of cost or market (net realizable value), determined under the first-in, first-out method. Inventory is recorded using standard cost, including material, labor and overhead costs, at December 31, 2014 and 2013. The Company periodically reviews inventories for potential impairment based on quantities on hand, expectations of future use, judgments based on quality control testing data and assessments of the likelihood of scrapping or obsoleting certain inventories.

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. 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 are amortized over the lesser of the estimated useful lives of the assets or the remaining lease term.

Patents

Costs associated with the purchase or licensing of patents associated with our commercialized products are capitalized. The Company reviews its capitalized patent costs periodically to determine that they have future value and an alternative future use. Costs related to patents that the Company is not actively pursuing for commercial purposes are expensed. The Company amortizes patent costs over the lesser of the duration of the patent term or an estimated useful life of 10 years, beginning with the date the patents are issued or acquired.

The Company periodically re-evaluates the original assumptions and rationale utilized in the establishment of the carrying value and estimated lives of all of its long-lived assets, including property and equipment and acquired patents. The determinants used for this evaluation include management’s estimate of the asset’s ability to generate positive income from operations and positive cash flow in future periods as well as the strategic significance of the asset to the Company’s business objective. The Company has not recognized any impairment losses through December 31, 2014.

Deferred Rent

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 when the Company takes possession of the leased property. The difference between rent expense and rent paid is accounted for as deferred rent, current portion of deferred rent was included in other current liabilities on the Company’s balance sheet. Landlord improvement allowances and other such lease incentives are recorded as property and equipment and as deferred rent and are amortized on a straight-line basis as a reduction to rent expense.

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, services, depreciation, allocated facilities and information services, collaboration payments and other indirect costs.

Income Taxes

The Company uses the asset and liability method of accounting for income taxes. Deferred income 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. A valuation allowance is recorded when it is more likely than not that some of the deferred tax assets will not be realized.

The Company is required to file federal and state income tax returns in the United States and various other state jurisdictions. The preparation of these income tax returns requires the Company to interpret the applicable tax laws and regulations in effect in such jurisdictions, which could affect the amount of tax paid by us. An amount is accrued for the estimate of additional tax liability, including interest and penalties, for any uncertain tax positions taken or expected to be taken in an income tax return. The Company reviews and updates the accrual for uncertain tax positions as more definitive information becomes available. For further information, see Note 8, “Income Taxes.”

Revenue Recognition

Revenue is generated from sales, in the United States, of the t:slim pump, disposable cartridges and infusion sets to individual customers and third-party distributors that re-sell the product to insulin-dependent diabetes customers. The Company is paid directly by customers who use the products, distributors and third-party insurance payors.

Revenue is recognized when persuasive evidence of an arrangement exists, delivery has occurred and title passed, the price is fixed or determinable, and collectability is reasonably assured. These criteria are applied as follows:

Ÿ	The evidence of an arrangement generally consists of contractual arrangements with distributors or direct customers.

Ÿ	Transfer of title and risk and rewards of ownership are passed upon shipment of the pump to distributors or upon delivery to the customer.

The selling prices are fixed and agreed upon based on the contracts with distributors, the customer and contracted insurance payors, if applicable. For sales to customers associated with insurance providers with whom there is no contract, revenue is recognized upon collection of cash at which time the price is determinable. The Company does not generally offer rebates to its distributors and customers.

Ÿ	The Company considers the overall creditworthiness and payment history of the distributor, customer and the contracted insurance payor in concluding whether collectability is reasonably assured.

Prior to the first quarter of 2013, t:slim pump sales were recorded as deferred revenue until the Company’s 30-day right of return expired because it did not have sufficient history to be able to reasonably estimate returns. At December 31, 2012, $1.9 million was recorded as deferred revenue. In the first quarter of 2013, the Company began recognizing t:slim pump revenue when all the revenue recognition criteria above were met, as it had established sufficient history in order to reasonably estimate product returns. As a result of this change, a one-time adjustment was recorded during 2013, to recognize previously deferred revenue and cost of sales of $1.9 million and $1.1 million, respectively.

Revenue Recognition for Arrangements with Multiple Deliverables

The Company considers the deliverables in its product offering as separate units of accounting and recognizes deliverables as revenue upon delivery only if (i) the deliverable has standalone value and (ii) if the arrangement includes a general right of return relative to the delivered item(s), delivery or performance of the undelivered item(s) is probable and substantially controlled by us. The Company allocates consideration to the separate units of accounting, unless the undelivered elements were deemed perfunctory and inconsequential. The Company uses the relative selling price method, in which allocation of consideration is based on vendor-specific objective evidence (VSOE) if available, third-party evidence (TPE), or if VSOE and TPE are not available, management’s best estimate of a standalone selling price (ESP) for the undelivered elements.

In February 2013, the FDA cleared t:connect, the Company’s cloud-based data management application, which is made available upon purchase by t:slim pump customers. This service is deemed an undelivered element at the time of the t:slim sale. Because the Company has neither VSOE nor TPE for this deliverable, the allocation of revenue is based on the Company’s ESP. The Company establishes its ESP based on estimated cost to provide such services, including consideration for a reasonable profit margin and corroborated by comparable market data. The Company allocates fair value based on management’s ESP to this element at the time of sale and is recognizing the revenue over the four-year hosting period. At December 31, 2014 and 2013, $0.7 million and $0.2 million were recorded as deferred revenue for the t:connect hosting service, respectively. All other undelivered elements at the time of sale are deemed inconsequential or perfunctory.

Product Returns

The Company offers a 30-day right of return for its t:slim pump customers from the date of shipment, provided a physician’s confirmation of the medical reason for the return is received. Estimated return allowances for sales returns are based on historical returned quantities as compared to t:slim pump shipments in those same periods. 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 product returns included in other current liabilities on the Company’s balance sheet at December 31, 2014 and 2013 was $0.3 million and $0.2 million, respectively. Actual product returns have not differed materially from estimated amounts reserved.

Warranty Reserve

The Company generally provides a four-year warranty on its t:slim pump to end user customers and may replace any pumps that do not function in accordance with the product specifications. Any pump returned to the Company may be refurbished and redeployed. Additionally, the Company offers a six-month warranty on t:slim cartridges and infusion sets. Estimated warranty costs are recorded at the time of shipment. Warranty costs are estimated based on the current expected replacement product cost, actual experience and expected failure rates from test studies performed in conjunction with the clearance of the Company’s product with the FDA to support the longevity and reliability of its t:slim pump. The Company evaluates the reserve quarterly and makes adjustments when appropriate. During 2013, the Company recorded $0.5 million decrease in warranty estimates due to the first-time availability of refurbished pumps to be used for replacements. In addition, of the $1.1 million warranty reserve at December 31, 2013, $0.3 million was related to potential replacement related to the voluntary product recall of selected lots of cartridges. No reserve existed for the recall at December 31, 2014. Actual warranty costs have not differed materially from estimated amounts reserved.

	December 31,
(in thousands)	2014			2013
Balance at beginning of the year	$	1,123		$	300
Provision for warranties issued during the period		3,709			3,515
Settlements made during the period		(2,858	)		(2,182	)
Decreases in warranty estimates		—			(510	)
Balance at September 30, 2014	$	1,974		$	1,123

Current portion		535			549
Non-current portion		1,439			574
Total	$	1,974		$	1,123

Stock-Based Compensation

Stock-based compensation cost is measured at the grant date, based on the estimated fair value of the award, and is recognized as expense over the employee’s requisite service period on a straight-line basis. The Company estimates the fair value of stock options and shares issued to employees under the ESPP using a Black-Scholes option-pricing model on the date of grant. The Black-Scholes option-pricing model requires the use of subjective assumptions including volatility, expected term, risk-free rate, and the fair value of the underlying common stock. For awards that vest based on service conditions, the Company recognizes expense using the straight-line method less estimated forfeitures. Prior to the Company’s initial public offering the estimated fair value of these awards was determined at the date of grant based upon the estimated fair value of the Company’s common stock. Subsequent to the Company’s initial public offering, the fair value of the common stock is based on observable market prices. As of December 31, 2014, there were no outstanding equity awards with market or performance conditions.

The Company records the expense for stock option grants to non-employees based on the estimated fair value of the stock options using the Black-Scholes option-pricing model. The fair value of non-employee awards is remeasured at each reporting period as the underlying awards vest unless the instruments are fully vested, immediately exercisable and nonforfeitable on the date of grant.

Warrant Liabilities

The Company issued freestanding warrants to purchase shares of common stock and convertible preferred stock in connection with the issuance of convertible notes payable in 2011 and 2012. The Company accounted for these warrants as a liability in the financial statements because either the Company did not have enough authorized shares to satisfy potential exercise of the common stock warrants and the number of shares to be issued upon their exercise was outside the control of the Company or because the underlying instrument into which the warrants are exercisable, Series C or Series D convertible preferred stock, contained deemed liquidation provisions that are outside of the control of the Company.

The warrants were recorded at fair value using either the Black-Scholes option pricing model, or a binomial lattice model, depending on the characteristics of the warrants at the time of the valuation. The fair value of these warrants was remeasured at each financial reporting period with any changes in fair value being recognized as a component of other income (expense) in the accompanying statements of operations and comprehensive loss. In connection with completion of the initial public offering in November 2013, the Company performed the final remeasurement of the warrant liability. For the year ended December 31, 2013 and 2012, $9.0 million other expense and $2.6 million other income were recorded as other income (expense) from the revaluations, respectively. There was no income or expense recorded for warrant revaluations in 2014.

Upon the closing of the initial public offering, warrants to purchase shares of Series D Preferred Stock automatically converted into warrants to purchase shares of common stock. The Company reclassified the warrant liability to stockholders’ equity as the warrants met the definition of an equity instrument.

Advertising Costs

The Company expenses advertising costs as they are incurred. For the years ended December 31, 2014, 2013 and 2012, advertising costs were $1.5 million, $0.7 million, and $68,000, respectively.

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.

Comprehensive Loss

All components of comprehensive loss, including net loss, are reported in the financial statements in the period in which they are recognized. Comprehensive 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.

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 net loss per share is calculated by dividing the net loss by the sum of the weighted-average number of dilutive common share equivalents outstanding for the period determined using the treasury stock method. Dilutive common share equivalents are comprised of convertible preferred stock, preferred stock warrants, common stock warrants, potential Employee Stock Purchase Plan (ESPP) awards, restricted common stock subject to repurchase and options outstanding under our stock plans. The calculation of diluted loss per share requires that, to the extent the average fair value of the underlying shares for the reporting period exceeds the exercise price of the warrants and the presumed exercise of such securities are dilutive to loss per share for the period, adjustments to net loss used in the calculation are required to remove the change in fair value of the warrants for the period. Likewise, adjustments to the denominator are required to reflect the related dilutive shares. For all periods presented, there is no difference in the number of shares used to calculate basic and diluted shares outstanding due to our net loss position and preferred stock warrants being anti-dilutive.

Potentially dilutive securities not included in the calculation of diluted net loss per share attributable to common stockholders because to do so would be anti-dilutive are as follows (in common stock equivalent shares):

(in thousands)	Year Ended December 31,
	2014		2013		2012
Convertible preferred stock outstanding		—		—		10,648
Warrants for convertible preferred stock		—		—		1,427
Warrants for common stock		1,007		1,358		—
Common stock options		2,233		4,539		—
Employee Stock Purchase Plan		128		138		—
Restricted common stock subject to repurchase		—		—		20
		3,368		6,035		12,095

Recent Accounting Pronouncements

In August 2014, the Financial Accounting Standards Board (“FASB”) issued an accounting standards update, which requires management of public and private companies to evaluate whether there are conditions and events that raise substantial doubt about the entity’s ability to continue as a going concern within one year after the financial statements are issued (or available to be issued, when applicable) and, if so, disclose that fact. Management will be required to make this evaluation for both annual and interim reporting periods, if applicable. Management is also required to evaluate and disclose whether its plans alleviate that doubt. The standard is effective for annual periods ending after December 15, 2016 and interim periods within annual periods beginning after December 15, 2016. The Company does not believe the adoption of this standard will have a material impact on its financial statement disclosures.

In May 2014, the FASB and the International Accounting Standards Board (“IASB”) issued a comprehensive new revenue recognition standard that will supersede existing revenue guidance under U.S. GAAP and International Financial Reporting Standards (“IFRS”). The standard’s core principle is that a company will recognize 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. In doing so, companies will need to use more judgment and make more estimates than under current guidance. These may include identifying performance obligations in the contract, estimating the amount of variable consideration to include in the transaction price and allocating the transaction price to each separate performance obligation. The guidance is effective for annual periods beginning after December 15, 2016, including interim periods within that period. The Company is in the process of assessing the future impact of the adoption of the standard on its financial statements.

In April 2014, the FASB issued an accounting standards update, which includes amendments that change the requirements for reporting discontinued operations and require additional disclosures about discontinued operations. Under the new guidance, only disposals representing a strategic shift in operations - that is, a major effect on the organization’s operations and financial results - should be presented as discontinued operations. Examples include a disposal of a major geographic area, a major line of business, or a major equity method investment. Additionally, the update requires expanded disclosures about discontinued operations that will provide financial statement users with more information about the assets, liabilities, income, and expenses of discontinued operations. The guidance is effective prospectively for fiscal years beginning after December 15, 2014 and interim periods within annual periods beginning on or after December 15, 2015. The Company does not believe the adoption of this standard will have a material impact on its financial position, results of operations or related financial statement disclosures.

Financial Statements Information

12 Months Ended

Dec. 31, 2014

Organization Consolidation And Presentation Of Financial Statements [Abstract]

Financial Statements Information

3. Financial Statements Information

Short-term investments

The Company invests excess cash in investment securities, principally debt instruments of 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, 2014 and 2013 (in thousands):

At December 31, 2014	Maturity (in years)	Amortized Cost		Unrealized Gain		Unrealized Loss			Estimated Fair Value
Available-for-sale investment securities:
Commercial paper	Less than 1	$	32,536	$	9	$	—		$	32,545
Government-sponsored enterprise securities	1 to 2		3,504		—		(1	)		3,503
		$	36,040	$	9	$	(1	)	$	36,048
Trading securities:
Mutual funds held for nonqualified deferred compensation plan participants		$	56	$	2	$	—		$	58
Total		$	36,096	$	11	$	(1	)	$	36,106

At December 31, 2013	Maturity (in years)	Amortized Cost		Unrealized Gain		Unrealized Loss		Estimated Fair Value
Available-for-sale investment securities:
Commercial paper	Less than 1	$	5,095	$	—	$	—	$	5,095
Total		$	5,095	$	—	$	—	$	5,095

Accounts Receivable

Accounts receivable consisted of the following at (in thousands):

	December 31,
	2014			2013
Accounts receivable	$	7,905		$	5,516
Less allowance for doubtful accounts		(253	)		(217	)
Total	$	7,652		$	5,299

Inventory

Inventory consisted of the following at (in thousands):

	December 31,
	2014			2013
Raw materials	$	7,085		$	6,363
Work in process		2,288			2,169
Finished goods		2,856			3,535
		12,229			12,067
Less: reserve		(316	)		(1,737	)
Total	$	11,913		$	10,330

The inventory reserve at December 31, 2013 included $0.9 million associated with the Company’s voluntary product recall.

Property and Equipment

Property and equipment consist of the following at (in thousands):

	December 31,
	2014			2013
Leasehold improvements	$	6,002		$	4,120
Computer equipment and software		5,171			4,155
Office furniture and equipment		3,538			2,681
Manufacturing and scientific equipment		9,110			6,510
		23,821			17,466
Less accumulated depreciation and amortization		(11,240	)		(7,580	)
Total	$	12,581		$	9,886

Depreciation and amortization expense related to property and equipment amounted to $4.1 million, $2.8 million and $1.9 million for the years ended December 31, 2014, 2013 and 2012, respectively.

Intangible Assets Subject to Amortization

In July 2012, the Company entered into an agreement pursuant to which certain rights were granted to patents and patent applications. Included in these rights are patents related to the Company’s commercialized products as well as patents that related to the products in development or future products. As consideration for these rights, the Company agreed to pay $5.0 million in license fees and a percentage of any associated sublicense revenues that may be received. To determine the fair value of the licensed and purchased intellectual property, the Company utilized a combination of royalty-relief and cost valuation approaches depending on the type of the patents. For the group of patents related to the commercialized products, the relief from royalty approach was utilized. Significant inputs in the valuation model included our projected revenues, estimated weighted average cost of capital, risk premium associated with the asset, and current market comparable royalty rates. For the patents associated with products in development, the cost approach was applied which utilized the costs associated with the filing and issuance of the patent to estimate the patent’s fair value. The Company used the relative fair values to allocate the purchase price between the two groups of patents. The fair value associated with the patents related to the commercialized products of $3.2 million was capitalized and is amortized over the weighted average patent remaining life of 10 years. The fair value associated with the rest of the patents of $1.8 million was expensed at the time of the contract execution and is recorded in the selling, general and administrative expenses line item in the statement of operations as the associated patents did not relate to the commercialized product.

Intangible assets subject to amortization consist of patents purchased or licensed that are related to the Company’s commercialized products. The following represents the capitalized patents at December 31, 2014 and 2013 (in thousands):

	December 31,
	2014			2013
Gross amount	$	3,247		$	3,173
Accumulated amortization		(806	)		(476	)
Total	$	2,441		$	2,697
Weighted average remaining amortization period (in months)		90			102

Amortization expense related to intangible assets subject to amortization amounted to $0.3 million, $0.3 million and $0.2 million for the years ended December 31, 2014, 2013 and 2012, respectively. The amortization expense is recorded in the cost of sales line item in the statement of operations. The estimated annual amortization is $0.3 million for 2015 and periods thereafter.

Fair Value Measurements

12 Months Ended

Dec. 31, 2014

Fair Value Disclosures [Abstract]

Fair Value Measurements

4. Fair Value Measurements

Authoritative guidance on fair value measurements defines fair value, establishes a consistent framework for measuring fair value, and expands disclosures for each major asset and liability category measured at fair value on either a recurring or nonrecurring basis. Fair value is an 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 quoted prices in active markets.

Level 2:		Inputs, other than the quoted prices in active markets, that are observable either directly or indirectly.

Level 3:		Unobservable inputs in which there is little or no market data, which require the reporting entity to develop its own assumptions.

The following table presents information about the Company’s financial assets measured at fair value on a recurring basis as of December 31, 2014 and 2013, 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
			December 31, 2014 Using
	December 31, 2014		Quoted Price in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Assets
Cash equivalents (1)	$	30,050	$	30,050	$	—	$	—
Commercial paper		32,545		—		32,545		—
Mutual funds held for nonqualified deferred compensation plan participants (2)		58		58		—		—
Government-sponsored enterprise securities		3,503		—		3,503		—
Total assets	$	66,156	$	33,611	$	32,545	$	—
Liabilities
Deferred compensation (2)	$	58	$	58	$	—	$	—
Total liabilities	$	58	$	58	$	—	$	—

(1)	Cash equivalents included money market funds and commercial paper with a maturity of three months or less from the date of purchase.

(2)

Deferred compensation plans are compensation plans directed by the Company and structured as a Rabbi Trust for certain executives and non-employee directors. The investment assets of the Rabbi Trust are valued using quoted market prices. The related deferred compensation liability represents the fair value of the investment assets.

			Fair Value Measurements at
			December 31, 2013
	December 31, 2013		Quoted Price in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Assets
Money market funds	$	115,112	$	115,112	$	—	$	—
Commercial paper		5,095		—		5,095		—
Total assets	$	120,207	$	115,112	$	5,095	$	—

There were no transfers between Level 1 and Level 2 securities during the years ended December 31, 2014 and 2013.

- 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

Convertible Notes Payable and Stock Warrants	12 Months Ended
Convertible Notes Payable and Stock Warrants	Dec. 31, 2014
Debt Disclosure [Abstract]
Convertible Notes Payable and Stock Warrants	5. Convertible Notes Payable and Stock Warrants 2011 Convertible Notes Payable In August 2011, the Company entered into a Note and Warrant Purchase Agreement (2011 Bridge Financing) with existing stockholders for an aggregate principal amount of approximately $13.0 million under unsecured convertible promissory notes. The convertible promissory notes bore interest at an annual rate of 8%, and all principal and interest were due and payable on March 31, 2012, unless earlier converted into preferred stock of the Company. In connection with the 2011 Bridge Financing and for cash proceeds of $1,000 (0.01% of the principal amount of the convertible promissory notes), the Company issued warrants to purchase shares of common stock up to the number of shares calculated by dividing 25% of the principal amount of the convertible promissory notes by the lesser of the next qualified equity financing per-share price, or $44.00. The warrants’ exercise price per share was $0.17. The warrants were immediately exercisable with an expiration in August 2021. The warrants’ fair value of approximately $0.3 million was recorded as a debt discount and amortized to interest expense over the term of the convertible promissory notes using the effective interest method. The estimated number of common shares issuable under the warrants was 43,955, although the actual number was not fixed. In March 2012, the Company extended the 2011 Bridge Financing maturity date to May 2012. No other terms were modified. The effective interest rate post-modification was less than the effective interest rate before modification and the Company concluded that this modification represented a troubled debt restructuring. The Company accounted for the modification on a prospective basis. In May 2012, the 2011 Bridge Financing maturity date of the associated convertible promissory notes was extended to August 31, 2012. Additionally, the warrant coverage provided in association with the notes was increased from 25% to 40% of the principal amount of the convertible promissory notes, and the shares purchasable under the warrants were changed from common stock to preferred stock. The preferred stock warrants’ exercise price was amended to $44.00 if exercised prior to the close of the next qualified equity financing, or by the per-share price of the next qualified equity financing if exercised after the close of the next qualified equity financing. The present value of the future cash flows under the modified terms described above did not exceed the present value of the future cash flows under the original terms by more than 10%. The Company treated this amendment as a modification and the incremental increase in the fair value of the warrants resulting from the modification of approximately $1.2 million was recorded as a discount to the convertible promissory notes and amortized over the remaining term of the convertible promissory notes using the effective interest method. The estimated number of preferred stock shares issuable under the warrants at the time of modification was 117,842. 2012 Convertible Notes Payable In May and July 2012, the Company entered into Note and Warrant Purchase Agreements (2012 Bridge Financing) with existing stockholders for an aggregate principal amount of approximately $12.2 million. The convertible promissory notes bore interest at an annual rate of 8%, and all principal and interest were due and payable on August 31, 2012, unless earlier converted into preferred stock of the Company. In connection with the 2012 Bridge Financing, the Company issued warrants to purchase shares of preferred stock up to the number of shares calculated by dividing 40% of the principal amount of the convertible promissory notes by $44.00 if exercised prior to the close of the next qualified equity financing, or by the per-share price of the next qualified equity financing if exercised after the close of the next qualified equity financing. The warrants’ exercise price was $44.00 if exercised prior to the close of the next qualified equity financing, or by the per-share price of the next qualified equity financing if exercised after the close of the next qualified equity financing. The warrants were immediately exercisable and with an expiration in May and July 2022. The 2012 Bridge Financing was completed substantially with the same parties as the 2011 Bridge Financing. At the time of each 2012 convertible promissory note issuance, the Company performed a comparison of the present value of the future cash flows under the original 2011 Bridge Financing terms and amended 2011 Bridge Financing terms as impacted by the 2012 Bridge Financing and determined that the change was more than 10%. The Company accounted for the issuance of the 2012 Bridge Financing as a debt extinguishment, and accordingly recorded the 2011 and 2012 Bridge Financing convertible promissory notes at fair value. The loss on extinguishment of $2.8 million was recorded in the statement of convertible preferred stock and stockholders’ equity (deficit) as a charge to additional paid-in capital in the period in which the extinguishment occurred as all these transactions were made with related parties. The amount in excess of additional paid-in capital was recorded into accumulated deficit. The loss on extinguishment was determined by calculating the difference between the net carrying amount of the extinguished debt (which includes principal, accrued interest, and unamortized discount, if any) and the fair value of the old and additional debt (which includes fair value of modified debt, fair value of additional warrants and any amendment related fees). Conversion to Series D Preferred Stock In August 2012, the Company completed the closing of a Series D financing, and all indebtedness under the 2011 Bridge Financing and 2012 Bridge Financing, aggregating approximately $26.4 million, including accrued interest, was automatically converted into shares of convertible Series D Preferred Stock at a per-share price equal to the per-share price of $4.40. All associated preferred stock warrants became warrants to purchase 2,288,316 shares of convertible Series D Preferred Stock at an exercise price of $4.40 per share. In November 2013, in connection with the closing of the initial public offering, all associated warrants to purchase shares of Series D Preferred Stock automatically converted into warrants to purchase 1,171,352 shares of our Common Stock at a weighted average exercise price of $7.37 per share. As of December 31, 2014, there were 1,006,577 common stock warrants outstanding.

Loan and Warrant Agreements

12 Months Ended

Dec. 31, 2014

Debt Disclosure [Abstract]

Loan and Warrant Agreements

6. Loan and Warrant Agreements

Silicon Valley Bank Loan

In March 2012, the Company entered into a Loan and Security Agreement with Silicon Valley Bank, drawing a bridge loan in the amount of $5.0 million (“SVB Bridge Loan”). Subsequent to the closing of the Series D financing, the SVB Bridge Loan was converted into a 24-month term loan (“SVB Term Loan”) in September 2012. The term loan accrued interest at an annual rate of 4%, with principal and accrued interest payments due monthly throughout the 24 month term. The SVB Term Loan also required a final payment of $0.3 million and a fee of $0.2 million if the loan was prepaid in its entirety prior to the end of the term of the loan.

In connection with the SVB Bridge Loan and SVB Term Loan, the Company issued an aggregate of 102,270 shares of Series D convertible preferred stock at an exercise price of $4.40 per share. In November 2013, in connection with the closing of the initial public offering, all SVB Series D Preferred Stock warrants automatically converted into warrants to purchase 61,033 shares of our Common Stock at a weighted average exercise price of $7.37 per share. The warrants were exercised in the first quarter of 2014.

In conjunction with the Capital Royalty Term Loan closing in January 2013, all principal, interest due and pre-payment fee amounts due under the SVB Term Loan were paid by the Company.

SVB Revolving Line of Credit

In January 2013, the Company entered into an amended loan agreement with Silicon Valley Bank, making available a revolving line of credit in the amount up to the lesser of $1.5 million or 75% of eligible accounts receivable. Interest-only payments at a rate of 6% per annum are payable monthly through the maturity date 24 months from the initial borrowing. Loans drawn under the agreement would be secured by the Company’s eligible accounts receivable and proceeds therefrom. Additionally, the terms of the revolving line of credit contain various affirmative and negative covenants. There were no amounts outstanding under this loan as of December 31, 2014 and 2013. The SVB revolving line of credit expired unused in January 2015.

Capital Royalty Term Loan

In December 2012, the Company executed a term loan agreement with Capital Royalty Partners II L.P. and Capital Royalty Partners II—Parallel Fund “A” L.P., together, Capital Royalty Partners, providing the Company access to up to $45 million under the arrangement, of which $30 million was available in January 2013, and an additional amount up to $15 million was available upon achievement of a 2013 revenue-based milestone. In January 2013, $30 million was drawn under the Agreement. The loan accrued interest at an annual rate of 14%.

The loan is collateralized by all assets of the Company. Additionally, the terms of the Term Loan Agreement contain various affirmative and negative covenants agreed to by the Company. Borrowings under the term loan are subject to non-occurrence of a material adverse change in our business or operations (financial or otherwise), or a material impairment of the prospect of repayment of obligations.

In connection with the Term Loan Agreement, in January 2013, the Company issued warrants to purchase 271,834 shares of the Company’s Common Stock at an exercise price of $0.02 per share. The warrants were immediately exercisable with an expiration in January 2023. Because the exercise price of these warrants was nominal, the Company used the fair value of the common stock of $1.61 at December 31, 2012 to value these warrants. The Company also paid $0.4 million financing fee to Capital Royalty Partners. The warrants’ fair value of approximately $0.4 million and financing fee of $0.4 million were recorded as a debt discount. Additionally, the Company paid $0.7 million to a third party for sourcing the Capital Royalty Term Loan, which was recorded as debt issuance cost. All fees and warrants value are amortized to interest expense over the remaining term using effective interest method. The warrants were exercised in the second quarter of 2014.

In April 2014, the Company entered into an Amended and Restated Term Loan Agreement (the “Amended and Restated Term Loan Agreement”) with the Lenders and other parties affiliated with Capital Royalty Partners. The Amended and Restated Term Loan Agreement primarily amended the terms of the Original Term Loan Agreement to reduce the borrowing limit to $30.0 million, to reduce the applicable interest rate from 14.0% to 11.5%, and to extend the interest only payment period from December 31, 2015 to March 31, 2018. Interest is payable, at the Company’s option, (i) in cash at a rate of 11.5% per annum or (ii) 9.5% of the 11.5% per annum in cash and 2.0% of the 11.5% per annum added to the principal of the loan and is subject to accruing interest. Interest-only payments are due quarterly on March 31, June 30, September 30 and December 31 of each year of the interest-only payment period. Thereafter, in addition to interest accrued during the period, the quarterly payments shall include an amount equal to the outstanding principal at March 31, 2018 divided by the remaining number of quarters prior to the end of the term of the loan which is March 31, 2020. The Amended and Restated Term Loan Agreement provides for prepayment fees of 3% of the outstanding balance of the loan if the loan is repaid prior to March 31, 2015. The prepayment fee is reduced by 1% per year for each subsequent year until maturity.

Certain affirmative and negative covenants were also amended. The principal financial covenants require that the Company attain minimum annual revenues of $30.0 million in 2014, $50.0 million in 2015, $65.0 million in 2016, $80.0 million in 2017 and $95.0 million thereafter. At December 31, 2014, the Company was in compliance with all of the covenants and has met the minimum annual revenue threshold for 2014.

At December 31, 2014, the principal balance outstanding under the Capital Royalty Term Loan was $30.0 million. Borrowings under the Amended and Restated Term Loan Agreement were used to refinance amounts outstanding under the Original Term Loan Agreement. The present value of the future cash flows under the modified terms described above did not exceed the present value of the future cash flows under the original terms by more than 10%. The Company treated this amendment as a modification and the facility fee of approximately $0.1 million recorded as a discount to the Amended and Restated Term Loan. The facility fee and the remaining balance of debt issuance costs and debt discount of the Original Term Loan are amortized to interest expense over the remaining term of the Amended and Restated Term Loan using the effective interest method.

Concurrently, the Company also entered into a new Term Loan Agreement (the “New Tranche Term Loan Agreement”) with the Lenders and other parties affiliated with Capital Royalty Partners, under which the Company may borrow up to an additional $30.0 million on or before March 31, 2015 at the same interest rate and on the same key terms as the Amended and Restated Term Loan Agreement.

Future minimum principal payments under the Term Loan Agreement, are as follows (in thousands):

Year ended December 31,
2015	$	—
2016		—
2017		—
2018		11,250
2019		15,000
Thereafter		3,750
Total	$	30,000
Less current portion of notes payable		—
Notes payable, net of current portion	$	30,000

In February 2015, the Company amended its Amended and Restated Term Loan Agreement, as well as its New Tranche Term Loan Agreement. Pursuant to this amendment, the interest only payment period was extended to December 31, 2019 from March 31, 2018 at the same interest rate and on the same key terms as the existing agreements. The principal balance will be due in full at the end of the term of the loan which is March 31, 2020 (see Note 13 “Subsequent Events”).

Stockholders' Equity (Deficit)

12 Months Ended

Dec. 31, 2014

Equity [Abstract]

Stockholders' Equity (Deficit)

7. Stockholders’ Equity (Deficit)

Convertible Preferred Stock

Prior to the conversion in the initial public offering in November 2013, the Company’s convertible preferred stock was classified as temporary equity on the accompanying balance sheets instead of in stockholders’ equity (deficit) in accordance with authoritative guidance for the classification and measurement of redeemable securities. Upon certain change in control events that were outside of our control, including liquidation, sale or transfer of control of the Company, holders of the convertible preferred stock could cause its redemption.

As of December 31, 2013, all outstanding convertible preferred stock had converted to common stock in conjunction with the initial public offering. Following its initial public offering, the Company filed an amended and restated certificate of incorporation to authorize 5,000,000 shares of undesignated preferred stock.

Common Stock

In November 2013, the Company completed its initial public offering of 8,000,000 shares of its common stock at a public offering price of $15.00 per share. Net cash proceeds from the initial public offering were approximately $108.3 million after deducting underwriting discounts, commissions and estimated offering related transaction costs payable by the Company. In November 2013, the underwriters also exercised their overallotment option and purchased an additional 1,200,000 shares of the Company’s common stock, from which the Company received cash proceeds, net of underwriting discounts and commissions, of approximately $16.7 million. In connection with the closing of the initial public offering, all of the Company’s shares of convertible preferred stock outstanding at the time of the offering were automatically converted into 13,403,747 shares of common stock. In addition, all outstanding preferred stock warrants were automatically converted into warrants to purchase an aggregate 1,171,352 shares of our common stock (see Note 4, “Fair Value Measurements”).

As of December 31, 2014, there were 23,654,745 shares of common stock outstanding. Each share of common stock is entitled to one vote. The holders of the common stock are also entitled to receive dividends whenever funds are legally available and when declared by our Board of Directors. Following our initial public offering, we filed an amended and restated certificate of incorporation to authorize 100,000,000 shares of common stock.

Stock Plans

In September 2006, the Company adopted the 2006 Stock Incentive Plan (the “2006 Plan”) under which, as amended, 2,685,605 shares of common stock were reserved for issuance to employees, non-employee directors and consultants of the Company.

The 2006 Plan provided for the grant of incentive stock options, non-statutory stock options, rights to purchase restricted common stock, stock appreciation rights, dividend equivalents, stock payments, and restricted stock units to eligible recipients. Recipients of incentive stock options and restricted common stock shall be eligible to purchase shares of the Company’s common stock at an exercise price equal to no less than the estimated fair market value of such stock on the date of grant. The 2006 Plan was closed in 2013 with the approval of the 2013 Stock Incentive Plan (the “2013 Plan”) and no further options will be granted under the 2006 Plan.

In October 2013, the Company’s board of directors approved the 2013 Plan. The 2013 Plan became effective immediately prior to the completion of the initial public offering. An initial 4,809,000 shares of common stock were reserved for issuance under the 2013 Plan. Under the 2013 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. Effective January 1, 2015, the shares available for issuance under the 2013 Plan were increased by 946,189 shares in accordance with an “evergreen” provision under the 2013 Plan.

As of December 31, 2014, 1,985,982 shares are available for future issuance under the 2013 Plan, and options to purchase 5,011,063 shares have been granted and are outstanding under the 2006 Plan and 2013 Plan.

Restricted Common Stock

The Company issued shares of restricted common stock totaling 23,872 shares in 2011. Proceeds from the issuance of the shares of restricted common stock totaled $0.2 million in 2011. The shares of restricted common stock were issued under the 2006 Plan to certain employees and nonemployee directors. Shares of restricted common stock granted under the 2006 Plan vested and were subject to repurchase according to the terms of the respective restricted stock agreement. Upon the closing of the initial public offering in November 2013, 11,935 shares of the Company’s unvested restricted common stock were automatically vested.

Common Stock Options

The maximum term of stock options granted under the 2006 Plan and 2013 Plan is ten years. The options generally vest 25% on the first anniversary of the original vesting date, with the balance vesting monthly over the remaining three years.

The following table summarizes stock option transactions for the 2006 Plan and 2013 Plan:

	Total Options			Weighted- Average Exercise Price		Weighted- Average Remaining Contractual Life (in years)		Aggregate Intrinsic Value (in thousands)
Outstanding at December 31, 2012		135,902		$	12.33		7.02	$	—
Granted		4,430,214		$	7.92
Exercised		(9,913	)	$	6.65			$	118
Canceled/forfeited/expired		(16,587	)	$	4.71
Outstanding at December 31, 2013		4,539,616		$	8.07		9.49	$	80,369
Granted		760,639		$	21.26
Exercised		(143,779	)	$	2.26			$	1,959
Canceled/forfeited/expired		(145,413	)	$	12.10
Outstanding at December 31, 2014		5,011,063		$	10.20		8.62	$	23,534
Vested and expected to vest at December 31, 2014		4,943,856		$	10.15		8.62	$	23,385
Exercisable at December 31, 2014		2,322,666		$	5.86		8.32	$	17,590

Employee Stock Purchase Plan

In October 2013, the Company adopted the 2013 Employee Stock Purchase Plan (the “ESPP”), which enables eligible employee to purchase shares of the Company’s common stock using their after tax payroll deductions, subject to certain conditions.

The ESPP initially authorized the issuance of 556,000 shares of common stock pursuant to purchase rights granted to employees. The number of shares of common stock reserved for issuance increases on January 1 of each calendar year, from January 1, 2014 through January 1, 2023, by the least of (a) one percent (1%) of the number of Shares issued and outstanding on the immediately preceding December 31, or (b) such lesser number of Shares as determined by the Administrator. On January 1, 2014, the number of shares of common stock reserved for issuance under our ESPP was automatically increased by 229,256 shares. On January 1, 2015, the number of shares of common stock reserved for issuance under our ESPP was automatically increased by an additional 236,547 shares. The ESPP is intended to qualify as an “employee stock purchase plan” within the meaning of Section 423 of the Code. As December 31, 2014, 251,390 shares of our common stock have been purchased under the ESPP and 533,866 shares remain available for issuance under the ESPP as of December 31, 2014.

Eligible employees may contribute, normally 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 will be 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, the ESPP consists of a two-year offering period with four six-month purchase periods.

Stock-Based Compensation.

The compensation cost that has been included in the statement of operations for all stock-based compensation arrangements was as follows (in thousands):

	Year Ended December 31,
	2014		2013		2012
Cost of sales	$	1,317	$	204	$	36
Selling, general & administrative		11,886		3,583		148
Research and development		1,792		669		62
Total	$	14,995	$	4,456	$	246

The total stock-based compensation capitalized as part of the cost of our inventory was $0.2 million and $0.3 million at December 31, 2014 and 2013, respectively.

At December 31, 2014, the total unamortized stock-based compensation expense of approximately $24.7 million will be recognized over the remaining vesting term of approximately 2.7 years.

Option grants to non-employees are valued using the fair-value-based method and are then quarterly re-measured and expensed over the period services are provided. For the years ended December 31, 2014 and 2013, the expense was $0.3 million and $0.1 million, respectively, and are included in the table above as component of selling, general and administrative expenses. Option grants to consultants resulted in an immaterial expense for the year ended December 31, 2012.

The Company estimates the fair value of stock options and shares issued to employees under the ESPP using a Black-Scholes option-pricing model on the date of grant. The fair value of equity instruments that are expected to vest are recognized and amortized on a straight-line basis over the requisite service period. The Black-Scholes option-pricing model incorporates various highly sensitive assumptions including expected volatility, expected term and risk-free interest rates.

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

	Stock Option
	Year Ended December 31,
	2014			2013			2012
Weighted average grant date fair value (per share)	$	14.29		$	7.52		$	15.60
Risk-free interest rate		1.8	%		1.4	%		1.1	%
Expected dividend yield		0.0	%		0.0	%		0.0	%
Expected volatility		76.3	%		79.0	%		70.2	%
Expected term (in years)		5.9			5.8			6.0

	ESPP
	Year Ended December 31,
	2014			2013
Weighted average grant date fair value (per share)	$	6.86		$	6.50
Risk-free interest rate		0.3	%		0.2	%
Expected dividend yield		0.0	%		0.0	%
Expected volatility		50.0	%		66.3	%
Expected term (in years)		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 expected dividend yield is zero because we have never declared or paid any cash dividends and do not presently plan to pay cash dividends in the foreseeable future.

Expected Volatility. Due to limited historical data, the expected volatility is estimated based on volatilities of a peer group of similar companies whose share prices are publicly available. The peer group consisted of other publicly-traded companies in the same industry and in a similar stage of development. The Company will continue to apply this process until a sufficient amount of historical information regarding the volatility of its own stock price becomes available.

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 estimate the expected term of ESPP using expected life for each tranche during the two year offering period.

The Company is also required to estimate forfeitures at the time of grant, and revise 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.

Common Stock Reserved for Future Issuance

The following shares of common stock are reserved for future issuance at December 31, 2014:

Common stock warrants outstanding			1,006,577
Stock options issued and outstanding			5,011,063
Authorized for future option grants			1,985,982
Employee stock purchase plan			533,866
			8,537,488

- Definition

The entire disclosure for shareholders' equity comprised of portions attributable to the parent entity and noncontrolling interest, including other comprehensive income. Includes, but is not limited to, balances of common stock, preferred stock, additional paid-in capital, other capital and retained earnings, accumulated balance for each classification of other comprehensive income and amount of comprehensive income.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
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Reference 12: http://www.xbrl.org/2003/role/presentationRef
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-Paragraph d
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Reference 15: http://www.xbrl.org/2003/role/presentationRef
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Reference 16: http://www.xbrl.org/2003/role/presentationRef
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+ Details

Income Taxes

12 Months Ended

Dec. 31, 2014

Income Tax Disclosure [Abstract]

Income Taxes

8. Income Taxes

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

	Year Ended December 31,
	2014			2013			2012
Tax at federal statutory rate	$	(27,065	)	$	(21,467	)	$	(11,225	)
State income tax, net of federal benefit		(3,912	)		(2,784	)		(1,793	)
Nondeductible convertible notes payable		—			3			617
Warrants revaluation		—			3,061			(869	)
Research and development credits		(646	)		(649	)		209
Stock-based compensation		1,973			831			82
Other		355			(39	)		73
Change in valuation allowance		29,366			21,044			12,906
	$	71		$	—		$	—

Significant components of the Company’s net deferred income tax assets at December 31, 2014 and 2013 are shown below (in thousands). A valuation allowance has been recorded to offset the net deferred tax asset as of December 31, 2014 and 2013, as the realization of such assets does not meet the more-likely-than-not threshold.

	December 31,
	2014			2013
Deferred tax assets:
Net operating loss (NOL)	$	69,600		$	47,996
Research and development tax credits		2,934			2,349
Capitalized R&D		10,750			7,686
Deferred rent		154			119
Stock-based and Accrued Compensation		6,481			2,490
Other		3,272			3,188
Total gross deferred tax assets		93,191			63,828
Less valuation allowance		(93,191	)		(63,828	)
Net deferred tax assets	$	—		$	—

The California NOL carry forwards will expire as follows (in thousands):

Year ended December 31,
2016	$	624
2017	$	2,052
Thereafter	$	106,758

As of December 31, 2014, the Company has accumulated federal and state net operating loss carryforwards of approximately $177.2 million and $190.6 million, respectively. The federal and state tax loss carryforwards begin to expire in 2026 and 2016, respectively, unless previously utilized. The Company also has federal and California research credit carryforwards of approximately $2.8 million and $3.2 million, respectively. The federal research credit carryforwards will begin expiring in 2028 unless previously utilized. The California research credit will carry forward indefinitely.

Utilization of the net operating losses and R&D credit carryforwards are subject to annual limitations due to ownership change limitations that have occurred or that could occur in the future, as required by Section 382 of the Internal Revenue Code of 1986, as amended (the Code), as well as similar state and foreign provisions. These ownership changes may limit the amount of net operating losses and R&D credit carryforwards that can be utilized annually to offset future taxable income and tax, respectively. In general, an “ownership change” as defined by Section 382 of the Code results from a transaction or series of transactions over a three-year period resulting in an ownership change of more than 50 percentage points of the outstanding stock of a company by certain stockholders.

The Company updated their Section 382/383 analysis, from January 1, 2012 through December 31, 2013, regarding the limitation of the net operating losses and research and development credits. Based upon the analysis, the Company determined that no ownership changes occurred during that period. The Company does not believe an ownership change has occurred through December 31, 2014. However, previous analysis determined that ownership changes have occurred in years prior to 2012, but will not have a material impact on the future utilization of such carryforwards.

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 derive 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, 2014 and 2013 (in thousands):

	Year Ended December 31,
	2014		2013		2012
Gross unrecognized tax benefits at the beginning of the year	$	1,912	$	1,422	$	779
Increases related to current year positions		476		349		176
Increases related to prior year positions		1,151		141		467
Expiration of unrecognized tax benefits		—		—		—
Gross unrecognized tax benefits at the end of the year	$	3,539	$	1,912	$	1,422

As of December 31, 2014, the Company has $3.0 million of unrecognized tax benefits that, if recognized and realized would impact the effective tax rate.

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 balance sheets and has not recognized interest and penalties in the statements of operations for the years ended December 31, 2014 and 2013. The Company does not expect any significant increases or decreases to its unrecognized tax benefits within the next 12 months.

The Company is subject to taxation in the United States and state jurisdictions. 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 net operating losses and research and development credits.

The American Taxpayer Relief Act of 2012 was enacted into law during the first quarter of 2013 and reinstated the United States federal research and development tax credit retroactively from January 1, 2012 through December 31, 2013. The effective tax rate for 2013 reflects a benefit of $0.4 million related to 2012 resulting from the retroactive extension of the United States research and development tax credit.

Collaborations	12 Months Ended
Collaborations	Dec. 31, 2014
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Collaborations	9. Collaborations DexCom Development and Commercialization Agreement In February 2012, the Company entered into a Development and Commercialization Agreement with DexCom, Inc. (DexCom Agreement) for the purpose of collaborating on the development and commercialization of an integrated system which incorporates the t:slim Insulin Delivery System with DexCom’s proprietary continuous glucose monitoring system. Under the DexCom Agreement, the Company paid DexCom $1.0 million at the commencement of the collaboration in 2012, and an additional $1.0 million in 2014, upon the achievement of a PMA submission to the FDA. Both payments were recorded as research and development costs in their respective years. The Company will make one additional $1.0 million payment upon the achievement of certain milestones. Additionally, the Company will reimburse DexCom up to $1.0 million of its development costs and is solely responsible for its own development costs. As of December 31, 2014, the Company had reimbursed DexCom $0.2 million of its development costs. For the years ended December 31, 2014, 2013, and 2012, the Company recognized research and development costs of $32,000, $95,000, and $39,000, respectively. Upon commercialization and as compensation for the non-exclusive license rights, the Company will also pay DexCom a royalty calculated at $100 per integrated system sold. JDRF Collaboration In January 2013, the Company entered into a research, development and commercialization agreement (“JDRF Agreement”) with the Juvenile Diabetes Research Foundation (“JDRF”) to develop the t:dual Infusion System, a first-of-its-kind, dual-chamber infusion pump for the management of diabetes. According to the terms of the JDRF Agreement, JDRF will provide research funding of up to $3.0 million based on the achievement of research and development milestones, not to exceed research costs incurred by the Company. Payments the Company receives to fund the collaboration efforts under the terms of the JDRF Agreement were recorded as restricted cash and current and long-term liabilities. The liabilities are recognized as an offset of research and development expenses straight-line over the remaining months until anticipated completion of the final milestone, only to the extent that the restricted cash is utilized to fund such development activities. The estimated completion date is re-evaluated each reporting period based on development progress through that date. As of December 31, 2014, we estimated the completion date to be September 2016. As of December 31, 2014, milestone payment achievements totaled $0.7 million, and research and development costs were offset cumulatively by $0.4 million. The research and development costs were offset by $0.2 million and $0.2 million for the years ended December 31, 2014 and 2013, respectively. The Company did not have any restricted cash balances related to the JDRF Agreement at December 31, 2014 or 2013.

Employee-Benefits	12 Months Ended
Employee-Benefits	Dec. 31, 2014
Defined Contribution Pension And Other Postretirement Plans Disclosure [Abstract]
Employee Benefits	10. Employee Benefits Employee 401(k) Plan The Company has a defined contribution 401(k) plan for employees who are at least 18 years of age. Employees are eligible to participate in the plan beginning on the first day of the calendar quarter following their date of hire. Under the terms of the plan, employees may make voluntary contributions as a percent of compensation. The Company does not provide a matching contribution program. Nonqualified Deferred Compensation Plan On June 16, 2014, the Company’s Board of Directors adopted and approved the Tandem Diabetes Care, Inc. Deferred Compensation Plan (the “Plan”). The Deferred Compensation Plan is a nonqualified deferred compensation program sponsored by the Company to provide its non-employee directors and certain of its management employees designated by the Board (or a committee appointed by the Board to administer the Plan) the opportunity to defer compensation under the Plan. The effective date for the Plan for the first year was July 1, 2014, and thereafter the plan year will be from January 1 to December 31. There is no limit to the amount that a participant may defer under the Plan whether in a particular plan year or in aggregate. In the discretion of the Board (or a committee appointed by the Board to administer the Plan), the Company may make additional contributions to be credited to the account of any or all participants in the Plan. All contributions by the participant, and any contributions that may be made by the Company, will be immediately fully vested. As of December 31, 2014, the Company has not made any contributions. Under the terms of the Plan, the Company has established a rabbi trust for the purpose of reserving any benefits that may become payable under the Plan. Distributions from the Plan will be governed by the Internal Revenue Code and the terms of the Plan. Company assets designated to pay benefits under the plan are held by a rabbi trust and are subject to the general creditors of the Company. The amounts deferred are invested in assets at the direction of the employee. The assets and liabilities of the rabbi trust are recorded at fair value and are accounted for as assets and liabilities of the Company. As of December 31, 2014, the Company held $58,000 in deferred compensation plan assets in short-term investments on its balance sheet that were invested in mutual funds. The fair market value of the assets held in the Deferred Compensation Plan was based on unadjusted quoted prices in active markets. The Company carries a corresponding deferred compensation liability of $58,000 as of December 31, 2014 in other long-term liabilities on its balance sheet.

Commitments and Contingencies

12 Months Ended

Dec. 31, 2014

Commitments And Contingencies Disclosure [Abstract]

Commitments and Contingencies

11. Commitments and Contingencies

From time to time, the Company may be subject to legal proceedings or regulatory encounters or other matters arising in the ordinary course of business, including actions with respect to intellectual property, employment, product liability, and contractual matters. In connection with these matters, the Company assesses, on a regular basis, the probability and range of possible loss based on the developments in these matters. A liability is recorded in the financial statements if it is believed to be probable that a loss has been incurred and the amount of the loss can be reasonably estimated. Because of the uncertainties related to the occurrence, amount, and range of loss on any pending actions, the Company is currently unable to predict their ultimate outcome, and, with respect to any pending litigation or claim where no liability has been accrued, to make a meaningful estimate of the reasonably possible loss or range of loss that could result from an unfavorable outcome. At December 31, 2014 and 2013, there were no material matters for which the negative outcome was considered probable or estimable.

Operating leases

In 2008, the Company entered into a noncancelable operating lease agreement to lease the Company’s corporate headquarters in San Diego, California, through August 2013.

In September 2009, the Company entered into a noncancelable operating lease agreement to expand the Company’s corporate headquarters to an adjacent building, as well as to extend the term of the aforementioned operating lease to co-terminate both leases in 2015.

In March 2012, the Company entered into a noncancelable operating lease agreement to increase the square footage of the Company’s corporate headquarters, as well as to consolidate all of the existing operating leases into a single lease agreement. The new agreement extends the term of the lease of all buildings to May 2017. Under the new lease, the monthly rent payments total approximately $0.1 million, excluding common area maintenance and related charges, and increase by a fixed percentage each year. Additionally, as a lease incentive from the landlord, the Company received a tenant improvement allowance of approximately $2 million for non-structural improvements to the building. The Company recorded this incentive as an increase to both property and equipment and deferred rent and it is amortized on a straight-line basis over the life of the lease.

In connection with the lease, the Company entered into a $0.4 million unsecured standby letter of credit arrangement with a bank under which the landlord of the building is the beneficiary. The standby letter of credit expired on March 31, 2013, but automatically extends for additional one-year periods unless notice of nonextension is provided. The final expiration of the standby letter of credit is August 31, 2017. The standby letters of credit previously entered into in connection with the pre-existing leases were canceled in March 2012.

On November 5, 2013, the Company entered into a noncancelable operating lease agreement to further extend the Company’s corporate headquarters to adjacent buildings (the “New Lease”), as well as to extend the term of the existing operating lease to terminate concurrently with the New Lease in 2019. There were no changes to the original lease payment schedule with the exception of extending the term for which the monthly rent would be increased by a fixed percentage each year on the anniversary of the rent commencement date of the New Lease.

Among the provisions of the New Lease, the monthly rent payments commenced in June 2014 and will increase by a fixed percentage each year on the anniversary of the rent commencement date. As a lease incentive from the landlord, the Company received a tenant improvement allowance of approximately $1.6 million for nonstructural improvements to the buildings. The Company recorded the incentives as increase to both property and equipment and deferred rent and it is amortized on a straight-line basis over the life of the lease.

In connection with the New Lease, the Company amended the existing standby letters of credit by increasing the value of the letter of credit to $0.5 million. The expiration of the standby letter of credit is July 14, 2019.

Deferred rent arising from rent escalation provisions and lease incentives totaled $3.4 million and $2.3 million at December 31, 2014 and 2013, respectively. Rent expense for the three years ended December 31, 2014 and 2013, was $2.1 million, $1.1 million, and $0.9 million respectively.

Future minimum payments under the aforementioned noncancelable operating leases for each of the five succeeding years following December 31, 2014 are as follows (in thousands):

2015	$	2,555
2016	$	2,815
2017	$	2,924
2018	$	3,024
2019	$	1,275
Thereafter	$	—
	$	12,593

Selected Quarterly Financial Data (Unaudited)

12 Months Ended

Dec. 31, 2014

Quarterly Financial Information Disclosure [Abstract]

Selected Quarterly Financial Data (Unaudited)

12. Selected Quarterly Financial Data (Unaudited)

Quarterly financial information for fiscal 2014 and 2013 are presented in the following table, in thousands, except per share data:

	For the Quarter Ending
	March 31			June 30			September 30			December 31
2014:
Revenue	$	8,066		$	10,254		$	13,513		$	17,889
Gross profit	$	867		$	3,448		$	4,396		$	6,537
Operating expenses	$	21,704		$	21,766		$	23,403		$	24,039
Operating loss	$	(20,837	)	$	(18,318	)	$	(19,007	)	$	(17,502	)
Net loss	$	(21,961	)	$	(19,197	)	$	(19,901	)	$	(18,465	)
Basic and diluted net loss per share (1)	$	(0.96	)	$	(0.83	)	$	(0.85	)	$	(0.78	)

2013:
Revenue	$	5,458		$	5,528		$	7,776		$	10,245
Gross profit	$	2,040		$	406		$	2,533		$	1,188
Operating expenses	$	9,207		$	14,083		$	14,660		$	17,651
Operating loss	$	(7,167	)	$	(13,677	)	$	(12,127	)	$	(16,463	)
Net loss	$	(11,163	)	$	(15,301	)	$	(13,061	)	$	(23,614	)
Basic and diluted net loss per share (1)	$	(53.77	)	$	(72.50	)	$	(60.96	)	$	(2.14	)

(1) Net loss per share is computed independently for each of the quarters presented. Therefore, the sum of the quarterly per-share calculations will not necessarily equal the annual per share calculation.

Subsequent Event	12 Months Ended
Subsequent Event	Dec. 31, 2014
Subsequent Events [Abstract]
Subsequent Event	13. Subsequent Event In February 2015, the Company amended its Amended and Restated Term Loan Agreement, as well as its New Tranche Term Loan Agreement. Pursuant to this amendment, the interest only payment period was extended to December 31, 2019 from March 31, 2018 at the same interest rate and on the same key terms as the existing agreements. The principal balance will be due in full at the end of the term of the loan which is March 31, 2020.

Organization and Basis of Presentation (Policies)

12 Months Ended

Dec. 31, 2014

Accounting Policies [Abstract]

The Company

Tandem Diabetes Care, Inc. is a medical device company focused on the design, development and commercialization of products for people with insulin-dependent diabetes. Unless the context requires otherwise, the terms the “Company” or “Tandem” refer to Tandem Diabetes Care, Inc.

The Company designed and commercialized its flagship product, the t:slim Insulin Delivery System, or t:slim, based on its proprietary technology platform and unique consumer-focused approach. The U.S. Food and Drug Administration (FDA) cleared t:slim in November 2011 and the Company commenced commercial sales of t:slim in the United States in August 2012. In January 2015, the Company received clearance from the FDA, to commercialize its next product, the t:flex Insulin Delivery System, or t:flex, for people with greater insulin needs. The Company intends to begin commercial sales of t:flex in the United States during the second quarter of 2015.

Tandem was originally incorporated in the state of Colorado on January 27, 2006 under the name Phluid Inc. On January 7, 2008, the Company was re-incorporated in the state of Delaware for the purposes of changing its legal name from Phluid Inc. to Tandem Diabetes Care, Inc. and changing its state of incorporation from Colorado to Delaware.

The Company has incurred operating losses since its inception and had an accumulated deficit of $248.7 million at December 31, 2014. The Company’s ability to achieve profitable operations primarily depends upon achieving a level of revenues adequate to support its cost structure. The Company has relied on its ability to fund its operations through private and public equity and debt financing. Management expects operating losses and negative cash flows to continue for the foreseeable future. The Company may elect to finance future operations using its existing term loan agreements or may pursue equity or debt financing through other sources. If necessary financing is not obtained or achieved, the Company will likely be required to reduce its current planned increases in expenditures, which could have an adverse impact on its ability to achieve its intended business objectives. There can be no assurance that equity or debt financing, beyond what is available under its existing term loan agreements, will be available on acceptable terms, or at all. Any equity financing may result in dilution to existing shareholders holders and any additional debt financing may include restrictive covenants.

Initial Public Offering

In November 2013, the Company completed its initial public offering of 8,000,000 shares of its common stock at a public offering price of $15.00 per share. Net cash proceeds from the initial public offering were approximately $108.3 million, after deducting underwriting discounts, commissions and estimated offering related transaction costs payable by the Company. In November 2013, the underwriters also exercised their overallotment option and purchased an additional 1,200,000 shares of the Company’s common stock, from which the Company received cash proceeds, net of underwriting discounts and commissions, of approximately $16.7 million. In connection with the closing of the initial public offering, all of the Company’s shares of convertible preferred stock outstanding at the time of the offering were automatically converted into 13,403,747 shares of common stock. In addition, all outstanding preferred stock warrants were automatically converted into warrants to purchase an aggregate 1,171,352 shares of our common stock (see Note 4, “Fair Value Measurements”).

Basis of Presentation

The accompanying financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America, or GAAP.

Reverse Stock Splits

In October 2013, the Board of Directors approved a 1-for-1.6756 reverse stock split of the Company’s common stock. All share and per share information included in the accompanying financial statements and notes to the financial statements give retroactive effect to this reverse stock split for the Company’s common stock.

Voluntary Recall

On January 10, 2014, the Company announced a voluntary recall of select lots of cartridges used with t:slim that may have been at risk of leaking. The cause of the recall was identified during the Company’s internal product testing. The recall was expanded on January 20, 2014 to include additional lots of affected cartridges used with t:slim. The Company incurred approximately $1.7 million in direct costs associated with the recall. The Company recorded a cost of sales charge of approximately $1.3 million in the fourth quarter of 2013 and recorded a cost of sales charge for the remainder in the first quarter of 2014 for affected cartridges shipped in 2014. The total cost of the recall consisted of approximately $0.7 million associated with the return and replacement of affected cartridges in the field and approximately $1.0 million for the write-off of affected cartridges within the Company’s internal inventory. As of December 31, 2014, the FDA has determined that the recall is terminated and the Company does not currently expect any further direct financial impact of the recall beyond these costs.

Use of Estimates

Segment Reporting

Cash and Cash Equivalents

The Company considers all highly liquid investments with a maturity of three months or less from the date of purchase to be cash equivalents.

Short Term Investments

Short-Term Investments

Restricted Cash

Accounts Receivable

Concentration of Credit Risk

The following table summarizes customers who accounted for 10% or more of net accounts receivable:

	December 31,
	2014			2013
Byram Healthcare		19.2	%		N/A
Edgepark Medical Supplies, Inc.		12.3	%		13.1	%
CCS Medical, Inc.		N/A			21.4	%

The following table summarizes customers who accounted for 10% or more of sales for the periods presented:

	December 31,
	2014			2013			2012
Edgepark Medical Supplies, Inc.		16.0	%		16.1	%		19.3	%
CCS Medical, Inc.		11.6	%		13.6	%	N/A
Byram Healthcare		10.9	%	N/A			N/A
Solara Medical Supplies, Inc.	N/A			N/A				15.7	%

Fair Value of Financial Instruments

Inventory

Long Lived Assets

Property and Equipment

Patents

Deferred Rent

Research and Development Costs

Income Taxes

Revenue Recognition

Ÿ	The evidence of an arrangement generally consists of contractual arrangements with distributors or direct customers.

Ÿ	Transfer of title and risk and rewards of ownership are passed upon shipment of the pump to distributors or upon delivery to the customer.

Ÿ	The Company considers the overall creditworthiness and payment history of the distributor, customer and the contracted insurance payor in concluding whether collectability is reasonably assured.

Revenue Recognition for Arrangements with Multiple Deliverables

Product Returns

Warranty Reserve

	December 31,
(in thousands)	2014			2013
Balance at beginning of the year	$	1,123		$	300
Provision for warranties issued during the period		3,709			3,515
Settlements made during the period		(2,858	)		(2,182	)
Decreases in warranty estimates		—			(510	)
Balance at September 30, 2014	$	1,974		$	1,123

Current portion		535			549
Non-current portion		1,439			574
Total	$	1,974		$	1,123

Stock-Based Compensation

Warrant Liabilities

Advertising Costs

The Company expenses advertising costs as they are incurred. For the years ended December 31, 2014, 2013 and 2012, advertising costs were $1.5 million, $0.7 million, and $68,000, respectively.

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.

Comprehensive Loss

Net Loss Per Share

(in thousands)	Year Ended December 31,
	2014		2013		2012
Convertible preferred stock outstanding		—		—		10,648
Warrants for convertible preferred stock		—		—		1,427
Warrants for common stock		1,007		1,358		—
Common stock options		2,233		4,539		—
Employee Stock Purchase Plan		128		138		—
Restricted common stock subject to repurchase		—		—		20
		3,368		6,035		12,095

Recent Accounting Pronouncements

Summary of Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2014

Accounting Policies [Abstract]

Summary of Customers Accounted for 10% or More

The following table summarizes customers who accounted for 10% or more of net accounts receivable:

	December 31,
	2014			2013
Byram Healthcare		19.2	%		N/A
Edgepark Medical Supplies, Inc.		12.3	%		13.1	%
CCS Medical, Inc.		N/A			21.4	%

The following table summarizes customers who accounted for 10% or more of sales for the periods presented:

	December 31,
	2014			2013			2012
Edgepark Medical Supplies, Inc.		16.0	%		16.1	%		19.3	%
CCS Medical, Inc.		11.6	%		13.6	%	N/A
Byram Healthcare		10.9	%	N/A			N/A
Solara Medical Supplies, Inc.	N/A			N/A				15.7	%

Summary of Reconciliation of Change in Product Warranty Liabilities

	December 31,
(in thousands)	2014			2013
Balance at beginning of the year	$	1,123		$	300
Provision for warranties issued during the period		3,709			3,515
Settlements made during the period		(2,858	)		(2,182	)
Decreases in warranty estimates		—			(510	)
Balance at September 30, 2014	$	1,974		$	1,123

Current portion		535			549
Non-current portion		1,439			574
Total	$	1,974		$	1,123

Schedule of Anti-Dilutive Securities

(in thousands)	Year Ended December 31,
	2014		2013		2012
Convertible preferred stock outstanding		—		—		10,648
Warrants for convertible preferred stock		—		—		1,427
Warrants for common stock		1,007		1,358		—
Common stock options		2,233		4,539		—
Employee Stock Purchase Plan		128		138		—
Restricted common stock subject to repurchase		—		—		20
		3,368		6,035		12,095

Financial Statements Information (Tables)

12 Months Ended

Dec. 31, 2014

Organization Consolidation And Presentation Of Financial Statements [Abstract]

Summary of Estimated Fair Value of Short-Term Investments

At December 31, 2014	Maturity (in years)	Amortized Cost		Unrealized Gain		Unrealized Loss			Estimated Fair Value
Available-for-sale investment securities:
Commercial paper	Less than 1	$	32,536	$	9	$	—		$	32,545
Government-sponsored enterprise securities	1 to 2		3,504		—		(1	)		3,503
		$	36,040	$	9	$	(1	)	$	36,048
Trading securities:
Mutual funds held for nonqualified deferred compensation plan participants		$	56	$	2	$	—		$	58
Total		$	36,096	$	11	$	(1	)	$	36,106

At December 31, 2013	Maturity (in years)	Amortized Cost		Unrealized Gain		Unrealized Loss		Estimated Fair Value
Available-for-sale investment securities:
Commercial paper	Less than 1	$	5,095	$	—	$	—	$	5,095
Total		$	5,095	$	—	$	—	$	5,095

Accounts Receivable

Accounts receivable consisted of the following at (in thousands):

	December 31,
	2014			2013
Accounts receivable	$	7,905		$	5,516
Less allowance for doubtful accounts		(253	)		(217	)
Total	$	7,652		$	5,299

Schedule of Inventories

Inventory consisted of the following at (in thousands):

	December 31,
	2014			2013
Raw materials	$	7,085		$	6,363
Work in process		2,288			2,169
Finished goods		2,856			3,535
		12,229			12,067
Less: reserve		(316	)		(1,737	)
Total	$	11,913		$	10,330

Property and Equipment

Property and equipment consist of the following at (in thousands):

	December 31,
	2014			2013
Leasehold improvements	$	6,002		$	4,120
Computer equipment and software		5,171			4,155
Office furniture and equipment		3,538			2,681
Manufacturing and scientific equipment		9,110			6,510
		23,821			17,466
Less accumulated depreciation and amortization		(11,240	)		(7,580	)
Total	$	12,581		$	9,886

Capitalized Patents

The following represents the capitalized patents at December 31, 2014 and 2013 (in thousands)

	December 31,
	2014			2013
Gross amount	$	3,247		$	3,173
Accumulated amortization		(806	)		(476	)
Total	$	2,441		$	2,697
Weighted average remaining amortization period (in months)		90			102

Fair Value Measurements (Tables)

12 Months Ended

Dec. 31, 2014

Fair Value Disclosures [Abstract]

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

			Fair Value Measurements at
			December 31, 2014 Using
	December 31, 2014		Quoted Price in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Assets
Cash equivalents (1)	$	30,050	$	30,050	$	—	$	—
Commercial paper		32,545		—		32,545		—
Mutual funds held for nonqualified deferred compensation plan participants (2)		58		58		—		—
Government-sponsored enterprise securities		3,503		—		3,503		—
Total assets	$	66,156	$	33,611	$	32,545	$	—
Liabilities
Deferred compensation (2)	$	58	$	58	$	—	$	—
Total liabilities	$	58	$	58	$	—	$	—

(1)	Cash equivalents included money market funds and commercial paper with a maturity of three months or less from the date of purchase.

(2)

			Fair Value Measurements at
			December 31, 2013
	December 31, 2013		Quoted Price in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)
Assets
Money market funds	$	115,112	$	115,112	$	—	$	—
Commercial paper		5,095		—		5,095		—
Total assets	$	120,207	$	115,112	$	5,095	$	—

Loan and Warrant Agreements (Tables)

12 Months Ended

Dec. 31, 2014

Debt Disclosure [Abstract]

Future Minimum Principal Payments Under Term Loan Agreement

Future minimum principal payments under the Term Loan Agreement, are as follows (in thousands):

Year ended December 31,
2015	$	—
2016		—
2017		—
2018		11,250
2019		15,000
Thereafter		3,750
Total	$	30,000
Less current portion of notes payable		—
Notes payable, net of current portion	$	30,000

Stockholders' Equity (Deficit) (Tables)

12 Months Ended

Dec. 31, 2014

Equity [Abstract]

Summary of Stock Option Transactions for 2006 Plan and 2013 Plan

The following table summarizes stock option transactions for the 2006 Plan and 2013 Plan:

	Total Options			Weighted- Average Exercise Price		Weighted- Average Remaining Contractual Life (in years)		Aggregate Intrinsic Value (in thousands)
Outstanding at December 31, 2012		135,902		$	12.33		7.02	$	—
Granted		4,430,214		$	7.92
Exercised		(9,913	)	$	6.65			$	118
Canceled/forfeited/expired		(16,587	)	$	4.71
Outstanding at December 31, 2013		4,539,616		$	8.07		9.49	$	80,369
Granted		760,639		$	21.26
Exercised		(143,779	)	$	2.26			$	1,959
Canceled/forfeited/expired		(145,413	)	$	12.10
Outstanding at December 31, 2014		5,011,063		$	10.20		8.62	$	23,534
Vested and expected to vest at December 31, 2014		4,943,856		$	10.15		8.62	$	23,385
Exercisable at December 31, 2014		2,322,666		$	5.86		8.32	$	17,590

Summary of Compensation Cost Included in Statement of Operations

The compensation cost that has been included in the statement of operations for all stock-based compensation arrangements was as follows (in thousands):

	Year Ended December 31,
	2014		2013		2012
Cost of sales	$	1,317	$	204	$	36
Selling, general & administrative		11,886		3,583		148
Research and development		1,792		669		62
Total	$	14,995	$	4,456	$	246

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

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

	Stock Option
	Year Ended December 31,
	2014			2013			2012
Weighted average grant date fair value (per share)	$	14.29		$	7.52		$	15.60
Risk-free interest rate		1.8	%		1.4	%		1.1	%
Expected dividend yield		0.0	%		0.0	%		0.0	%
Expected volatility		76.3	%		79.0	%		70.2	%
Expected term (in years)		5.9			5.8			6.0

	ESPP
	Year Ended December 31,
	2014			2013
Weighted average grant date fair value (per share)	$	6.86		$	6.50
Risk-free interest rate		0.3	%		0.2	%
Expected dividend yield		0.0	%		0.0	%
Expected volatility		50.0	%		66.3	%
Expected term (in years)		1.3			1.3

Schedule of Shares of Common Stock Reserved for Future Issuance

The following shares of common stock are reserved for future issuance at December 31, 2014:

Common stock warrants outstanding			1,006,577
Stock options issued and outstanding			5,011,063
Authorized for future option grants			1,985,982
Employee stock purchase plan			533,866
			8,537,488

Income Taxes (Tables)

12 Months Ended

Dec. 31, 2014

Income Tax Disclosure [Abstract]

Schedule of Components of Income Tax Expense (Benefit)

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

	Year Ended December 31,
	2014			2013			2012
Tax at federal statutory rate	$	(27,065	)	$	(21,467	)	$	(11,225	)
State income tax, net of federal benefit		(3,912	)		(2,784	)		(1,793	)
Nondeductible convertible notes payable		—			3			617
Warrants revaluation		—			3,061			(869	)
Research and development credits		(646	)		(649	)		209
Stock-based compensation		1,973			831			82
Other		355			(39	)		73
Change in valuation allowance		29,366			21,044			12,906
	$	71		$	—		$	—

Schedule of Deferred Tax Assets and Liabilities

	December 31,
	2014			2013
Deferred tax assets:
Net operating loss (NOL)	$	69,600		$	47,996
Research and development tax credits		2,934			2,349
Capitalized R&D		10,750			7,686
Deferred rent		154			119
Stock-based and Accrued Compensation		6,481			2,490
Other		3,272			3,188
Total gross deferred tax assets		93,191			63,828
Less valuation allowance		(93,191	)		(63,828	)
Net deferred tax assets	$	—		$	—

California NOL Carry Forwards Expiration

The California NOL carry forwards will expire as follows (in thousands):

Year ended December 31,
2016	$	624
2017	$	2,052
Thereafter	$	106,758

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, 2014 and 2013 (in thousands):

	Year Ended December 31,
	2014		2013		2012
Gross unrecognized tax benefits at the beginning of the year	$	1,912	$	1,422	$	779
Increases related to current year positions		476		349		176
Increases related to prior year positions		1,151		141		467
Expiration of unrecognized tax benefits		—		—		—
Gross unrecognized tax benefits at the end of the year	$	3,539	$	1,912	$	1,422

Commitments and Contingencies (Tables)

12 Months Ended

Dec. 31, 2014

Commitments And Contingencies Disclosure [Abstract]

Schedule of Future Minimum Payments Under Noncancelable Operating Leases

Future minimum payments under the aforementioned noncancelable operating leases for each of the five succeeding years following December 31, 2014 are as follows (in thousands):

2015	$	2,555
2016	$	2,815
2017	$	2,924
2018	$	3,024
2019	$	1,275
Thereafter	$	—
	$	12,593

Selected Quarterly Financial Data (Unaudited) (Tables)

12 Months Ended

Dec. 31, 2014

Quarterly Financial Information Disclosure [Abstract]

Quarterly Financial Information

Quarterly financial information for fiscal 2014 and 2013 are presented in the following table, in thousands, except per share data:

	For the Quarter Ending
	March 31			June 30			September 30			December 31
2014:
Revenue	$	8,066		$	10,254		$	13,513		$	17,889
Gross profit	$	867		$	3,448		$	4,396		$	6,537
Operating expenses	$	21,704		$	21,766		$	23,403		$	24,039
Operating loss	$	(20,837	)	$	(18,318	)	$	(19,007	)	$	(17,502	)
Net loss	$	(21,961	)	$	(19,197	)	$	(19,901	)	$	(18,465	)
Basic and diluted net loss per share (1)	$	(0.96	)	$	(0.83	)	$	(0.85	)	$	(0.78	)

2013:
Revenue	$	5,458		$	5,528		$	7,776		$	10,245
Gross profit	$	2,040		$	406		$	2,533		$	1,188
Operating expenses	$	9,207		$	14,083		$	14,660		$	17,651
Operating loss	$	(7,167	)	$	(13,677	)	$	(12,127	)	$	(16,463	)
Net loss	$	(11,163	)	$	(15,301	)	$	(13,061	)	$	(23,614	)
Basic and diluted net loss per share (1)	$	(53.77	)	$	(72.50	)	$	(60.96	)	$	(2.14	)

Organization and Basis of Presentation - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands		1 Months Ended	3 Months Ended	12 Months Ended
	Jan. 10, 2014	Nov. 30, 2013	Dec. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Organization And Basis Of Presentation [Line Items]
Incorporation date				Jan. 27, 2006
Reincorporation date				Jan. 07, 2008
Operating losses and accumulated deficit			$ (169,191)	$ (248,715)	$ (169,191)
Proceeds from initial public offering					125,040
Net proceeds from additional issuance of stock				$ 3,664	2,575	$ 35
Reverse stock split				1-for-1.6756
Direct costs associated with the recall	$ 1,700
Return and replacement of affected cartridges	700
Provision for inventory reserve	$ 1,000			$ 163	$ 815	$ 335
Cost of sales [Member]
Organization And Basis Of Presentation [Line Items]
Direct costs associated with the recall			$ 1,300
Initial Public Offering [Member]
Organization And Basis Of Presentation [Line Items]
Shares offered for public offering		8,000,000
Shares offering price per share		$ 15.00
Proceeds from initial public offering		$ 108,300
Additional shares issued to underwriters		1,200,000
Net proceeds from additional issuance of stock		$ 16,700
Converted number of common stock		13,403,747
Conversion of warrants to common shares		1,171,352

Summary of Significant Accounting Policies - Additional Information (Detail)	12 Months Ended
	Dec. 31, 2014 USD ($) Segment shares	Dec. 31, 2013 USD ($) shares	Dec. 31, 2012 USD ($) shares
Summary Of Significant Accounting Policies [Line Items]
Number of operating segments \| Segment	1
Investment held-to-maturity	$ 0	$ 0
Restricted cash	$ 2,000,000	2,050,000
Receivables considered as uncollectible, maximum past due days	120 days
Deferred revenue		1,900,000	$ 1,900,000
Cost of sales		1,100,000
Revenue recognition hosting period	4 years
Offered period for sales return	30 days
Allowance for product returns	$ 300,000	200,000
Warranty reserve	1,974,000	1,123,000	$ 300,000
Other current liabilities	$ 2,663,000	4,086,000
Decreases in warranty estimates		$ (510,000)
Equity awards outstanding \| shares	5,011,063	4,539,616	135,902
Change in fair value of common and preferred stock warrants, Income (expenses)	$ 0	$ (9,002,000)	$ 2,556,000
Advertising cost	$ 1,500,000	700,000	$ 68,000
Performance Shares
Summary Of Significant Accounting Policies [Line Items]
Equity awards outstanding \| shares	0
Warranty reserves [Member]
Summary Of Significant Accounting Policies [Line Items]
Warranty reserve	$ 0	1,100,000
Other current liabilities		300,000
Connect Hosting Service [Member]
Summary Of Significant Accounting Policies [Line Items]
Deferred revenue	$ 700,000	200,000
Slim Pump [Member]
Summary Of Significant Accounting Policies [Line Items]
Warranty period offered	4 years
Slim cartridges and infusion sets [Member]
Summary Of Significant Accounting Policies [Line Items]
Warranty period offered	6 months
Patents [Member]
Summary Of Significant Accounting Policies [Line Items]
Company amortizes patent costs over their estimated useful life	10 years
Minimum [Member]
Summary Of Significant Accounting Policies [Line Items]
Estimated useful lives of the assets	3 years
Maximum [Member]
Summary Of Significant Accounting Policies [Line Items]
Estimated useful lives of the assets	7 years
Original Term Loan Agreement [Member]
Summary Of Significant Accounting Policies [Line Items]
Restricted cash	$ 2,000,000	$ 2,000,000

Summary of Significant Accounting Policies - Summary of Customers Accounted for 10% or More (Detail)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Accounts receivable [Member] \| Byram Healthcare [Member]
Concentration Risk [Line Items]
Customers accounted for 10% or more	19.20%
Accounts receivable [Member] \| Edgepark Medical Supplies, Inc. [Member]
Concentration Risk [Line Items]
Customers accounted for 10% or more	12.30%	13.10%
Accounts receivable [Member] \| CCS Medical, Inc. [Member]
Concentration Risk [Line Items]
Customers accounted for 10% or more		21.40%
Sales [Member] \| Byram Healthcare [Member]
Concentration Risk [Line Items]
Customers accounted for 10% or more	10.90%
Sales [Member] \| Edgepark Medical Supplies, Inc. [Member]
Concentration Risk [Line Items]
Customers accounted for 10% or more	16.00%	16.10%	19.30%
Sales [Member] \| CCS Medical, Inc. [Member]
Concentration Risk [Line Items]
Customers accounted for 10% or more	11.60%	13.60%
Sales [Member] \| Solara Medical Supplies, Inc. [Member]
Concentration Risk [Line Items]
Customers accounted for 10% or more			15.70%

Summary of Significant Accounting Policies - Summary of Reconciliation of Change in Product Warranty Liabilities (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013
Movement In Standard And Extended Product Warranty Increase Decrease Roll Forward
Balance at beginning of the year	$ 1,123	$ 300
Provision for warranties issued during the period	3,709	3,515
Settlements made during the period	(2,858)	(2,182)
Decreases in warranty estimates		(510)
Balance at September 30, 2014	1,974	1,123
Current portion	535	549
Non-current portion	$ 1,439	$ 574

Summary of Significant Accounting Policies - Schedule of Anti-Dilutive Securities (Detail) - shares	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share, amount	3,368,000	6,035,000	12,095,000
Warrants for convertible preferred stock [Member]
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share, amount			1,427,000
Warrants for common stock [Member]
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share, amount	1,007,000	1,358,000
Common stock options [Member]
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share, amount	2,233,000	4,539,000
Employee stock purchase plan [Member]
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share, amount	128,000	138,000
Restricted common stock subject to repurchase [Member]
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share, amount			20,000
Convertible Preferred Stock [Member]
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation of earnings per share, amount			10,648,000

Financial Statements Information - Summary of Estimated Fair Value of Short-Term Investments (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013
Cash Cash Equivalents And Short Term Investments [Line Items]
Short-term investments, Amortized Cost	$ 36,040	$ 5,095
Short-term investments, Unrealized Gain	9
Short-term investments, Unrealized Loss	(1)
Short-term investments, Estimated Fair Value	36,048	$ 5,095
Short-term investments, Amortized Cost	36,096
Short-term investments, Unrealized Gain	11
Short-term investments, Unrealized Loss	(1)
Short-term investments, Estimated Fair Value	$ 36,106
Commercial paper [Member]
Cash Cash Equivalents And Short Term Investments [Line Items]
Short-term investments, Maturity (in years)	Less than 1	Less than 1
Short-term investments, Amortized Cost	$ 32,536	$ 5,095
Short-term investments, Unrealized Gain	9
Short-term investments, Estimated Fair Value	$ 32,545	$ 5,095
Government-sponsored enterprise securities [Member]
Cash Cash Equivalents And Short Term Investments [Line Items]
Short-term investments, Maturity (in years)	1 to 2
Short-term investments, Amortized Cost	$ 3,504
Short-term investments, Unrealized Loss	(1)
Short-term investments, Estimated Fair Value	3,503
Trading securities — mutual funds held for nonqualified deferred compensation plan participants [Member]
Cash Cash Equivalents And Short Term Investments [Line Items]
Short-term investments, Amortized Cost	56
Short-term investments, Unrealized Gain	2
Short-term investments, Estimated Fair Value	$ 58

Financial Statements Information - Summary of Accounts receivable (Detail) - USD ($) $ in Thousands	Dec. 31, 2014	Dec. 31, 2013
Accounts Receivable Net [Abstract]
Accounts receivable	$ 7,905	$ 5,516
Less allowance for doubtful accounts	(253)	(217)
Total	$ 7,652	$ 5,299

Financial Statements Information - Summary of Inventory (Detail) - USD ($) $ in Thousands	Dec. 31, 2014	Dec. 31, 2013
Inventory Disclosure [Abstract]
Raw materials	$ 7,085	$ 6,363
Work in process	2,288	2,169
Finished goods	2,856	3,535
Inventory gross	12,229	12,067
Less: reserve	(316)	(1,737)
Total	$ 11,913	$ 10,330

Financial Statements Information - Additional Information (Detail) - USD ($) $ in Thousands	1 Months Ended	12 Months Ended
	Jul. 31, 2012	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Schedule Of Balance Sheet Components [Line Items]
Inventory reserve		$ 316	$ 1,737
Depreciation, Depletion and Amortization, Nonproduction		4,100	2,800	$ 1,900
License Fees Received	$ 5,000
Patent Related To Commercialized Products	$ 3,200
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life	10 years
Selling, general and administrative	$ 1,800	75,121	44,522	22,691
Amortization of Intangible Assets		300	300	$ 200
Estimated annual amortization		$ 300
Product Recalls [Member]
Schedule Of Balance Sheet Components [Line Items]
Inventory reserve			$ 900

Financial Statements Information - Summary of Property and Equipment (Detail) - USD ($) $ in Thousands	Dec. 31, 2014	Dec. 31, 2013
Property Plant And Equipment [Line Items]
Property and equipment, gross	$ 23,821	$ 17,466
Less accumulated depreciation and amortization	(11,240)	(7,580)
Total property and equipment, net	12,581	9,886
Leasehold improvements [Member]
Property Plant And Equipment [Line Items]
Property and equipment, gross	6,002	4,120
Computer equipment and software [Member]
Property Plant And Equipment [Line Items]
Property and equipment, gross	5,171	4,155
Office furniture and equipment [Member]
Property Plant And Equipment [Line Items]
Property and equipment, gross	3,538	2,681
Manufacturing and scientific equipment [Member]
Property Plant And Equipment [Line Items]
Property and equipment, gross	$ 9,110	$ 6,510

Financial Statements Information - Summary of capitalized Patents (Detail) - USD ($) $ in Thousands	Dec. 31, 2014	Dec. 31, 2013
Indefinite Lived Intangible Assets By Major Class [Line Items]
Weighted average remaining amortization period (in months)	$ 90	$ 102
Patents [Member]
Indefinite Lived Intangible Assets By Major Class [Line Items]
Gross amount	3,247	3,173
Accumulated amortization	(806)	(476)
Total	$ 2,441	$ 2,697

Fair Value Measurements - Schedule of Financial Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) - USD ($) $ in Thousands	Dec. 31, 2014	Dec. 31, 2013
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Total assets	$ 66,156	$ 120,207
Total liabilities	58
Cash equivalents [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Total assets	30,050
Commercial paper [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Total assets	32,545	5,095
Mutual funds held for nonqualified deferred compensation plan participants [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Total assets	58
Government-sponsored enterprise securities [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Total assets	3,503
Money Market Funds [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Total assets		115,112
Deferred compensation [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Total liabilities	58
Level 1 [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Total assets	33,611	115,112
Total liabilities	58
Level 1 [Member] \| Cash equivalents [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Total assets	30,050
Level 1 [Member] \| Mutual funds held for nonqualified deferred compensation plan participants [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Total assets	58
Level 1 [Member] \| Money Market Funds [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Total assets		115,112
Level 1 [Member] \| Deferred compensation [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Total liabilities	58
Level 2 [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Total assets	32,545	5,095
Level 2 [Member] \| Commercial paper [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Total assets	32,545	$ 5,095
Level 2 [Member] \| Government-sponsored enterprise securities [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Total assets	$ 3,503

Fair Value Measurements - Schedule of Financial Assets and Liabilities Measured at Fair Value on Recurring Basis (Parenthetical) (Detail)	12 Months Ended
	Dec. 31, 2014
Maximum [Member]
Fair Value Balance Sheet Grouping Financial Statement Captions [Line Items]
Cash equivalents maturity term	3 months

Fair Value Measurements - Additional Information (Detail) - USD ($)	Dec. 31, 2014	Dec. 31, 2013
Fair Value Disclosures [Abstract]
Transfer between level 1 and level 2 securities	$ 0	$ 0

Convertible Notes Payable and Stock Warrants - Additional Information (Detail) - USD ($)	1 Months Ended		12 Months Ended
	Nov. 30, 2013	Aug. 31, 2012	Dec. 31, 2014	Dec. 31, 2012	Jul. 31, 2012	May 31, 2012	Aug. 31, 2011
Debt Instrument [Line Items]
Loss on extinguishment of convertible notes payable				$ (2,771,000)
Common Stock [Member]
Debt Instrument [Line Items]
Number of common share issuable	1,171,352
Weighted average warrant exercise price of common stock	$ 7.37
Warrants outstanding			1,006,577
Series D Preferred Stock [Member]
Debt Instrument [Line Items]
Exercise price per share		$ 4.40
Number of common share issuable		2,288,316
Financing cost related to shares		$ 26,400,000
Stock conversion price per share		$ 4.40
2011 Convertible Notes Payable [Member]
Debt Instrument [Line Items]
Aggregate principal amount							$ 13,000,000
Interest annual rate							8.00%
Promissory note interest payable date			Mar. 31, 2012
Proceeds from convertible notes payable			$ 1,000
Interest on convertible promissory notes			0.01%
Convertible terms of conversion feature			The Company issued warrants to purchase shares of common stock up to the number of shares calculated by dividing 25% of the principal amount of the convertible promissory notes by the lesser of the next qualified equity financing per-share price, or $44.00.
Amortization of debt discount			$ 300,000
Exercise price per share						$ 44.00
Incremental increase in fair value of warrant			$ 1,200,000
2011 Convertible Notes Payable [Member] \| Minimum [Member]
Debt Instrument [Line Items]
Warrant coverage percentage provided to all purchases of preferred stock						25.00%
Discount rate used in calculation of present value of future cash flows			10.00%
2011 Convertible Notes Payable [Member] \| Maximum [Member]
Debt Instrument [Line Items]
Warrant coverage percentage provided to all purchases of preferred stock						40.00%
2011 Convertible Notes Payable [Member] \| Common Stock [Member]
Debt Instrument [Line Items]
Exercise price per share			$ 0.17
Number of common share issuable			43,955
Warrants exercisable and expire period, description			The warrants were immediately exercisable with an expiration in August 2021.
Warrants expire period			2021-08
2011 Convertible Notes Payable [Member] \| Convertible Preferred Stock [Member]
Debt Instrument [Line Items]
Number of common share issuable			117,842
2012 Convertible Notes Payable [Member]
Debt Instrument [Line Items]
Aggregate principal amount					$ 12,200,000	$ 12,200,000
Interest annual rate					8.00%	8.00%
Promissory note interest payable date			Aug. 31, 2012
Exercise price per share			$ 44.00
Warrants exercisable and expire period, description			The warrants were immediately exercisable and with an expiration in May and July 2022.
Ratio of the number of warrants issued for each share of preferred stock purchased			40.00%
Loss on extinguishment of convertible notes payable				$ (2,771,000)
2012 Convertible Notes Payable [Member] \| Minimum [Member]
Debt Instrument [Line Items]
Discount rate used in calculation of present value of future cash flows				10.00%

Loan and Warrant Agreements - Additional Information (Detail) - USD ($)		1 Months Ended		12 Months Ended
	Apr. 04, 2014	Nov. 30, 2013	Jan. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Mar. 31, 2012
Debt Instrument [Line Items]
Revolving line of credit amount outstanding				$ 0	$ 0
Revolving line of credit expiring date			Jan. 31, 2015
Loan outstanding				30,000,000
Minimum annual revenues attainable in 2014				30,000,000
Minimum annual revenues attainable in 2015				50,000,000
Minimum annual revenues attainable in 2016				65,000,000
Minimum annual revenues attainable in 2017				80,000,000
Minimum annual revenues attainable in 2018				95,000,000
Capital Royalty Partners [Member]
Debt Instrument [Line Items]
Loan outstanding				$ 30,000,000
SVB Revolving Line of Credit [Member]
Debt Instrument [Line Items]
Available revolving line of credit			$ 1,500,000
Revolving line of credit facility as percentage of accounts receivable			75.00%
Revolving line of credit interest rate				6.00%
Interest-only payments description				Interest-only payments at a rate of 6% per annum are payable monthly through the maturity date 24 months from the initial borrowing.
Maturity date from the initial borrowings				24 months
Original Term Loan Agreement [Member]
Debt Instrument [Line Items]
Interest rate				14.00%
Warrants issued to purchase common stock			271,834
Exercise price per share			$ 0.02
Available revolving line of credit			$ 30,000,000			$ 45,000,000
Additional loan amount available under agreement			15,000,000
Loan outstanding			$ 30,000,000
Warrants expire period			2023-01
Fair Value Of Common Stock						$ 1.61
Warrants fair value recorded as debt discount				$ 400,000
Financing fee of warrant recorded as debt discount				400,000
Debt Issuance Costs				700,000
Original Term Loan Agreement [Member] \| Capital Royalty Partners [Member]
Debt Instrument [Line Items]
Debt financing fee				$ 400,000
Amended and Restated Term Loan Agreement [Member]
Debt Instrument [Line Items]
Interest rate	11.50%
Available revolving line of credit	$ 30,000,000
Interest-only payments description				Interest is payable, at the Company’s option, (i) in cash at a rate of 11.5% per annum or (ii) 9.5% of the 11.5% per annum in cash and 2.0% of the 11.5% per annum is added to the principal of the loan and is subject to accruing interest. Interest-only payments are due quarterly on March 31, June 30, September 30 and December 31 of each year of the interest-only payment period.
Interest payable as cash	9.50%
Compounded interest payable	2.00%
Prepayment fee percentage	3.00%
Prepayment fee percentage on loan repayment	1.00%
Maturity of term loan	Mar. 31, 2020
Present value of the future cash flows				10.00%
Debt discount				$ 100,000
Amended and Restated Term Loan Agreement [Member] \| Minimum [Member]
Debt Instrument [Line Items]
Interest rate	11.50%
Interest payment period	Dec. 31, 2015
Amended and Restated Term Loan Agreement [Member] \| Maximum [Member]
Debt Instrument [Line Items]
Interest rate	14.00%
Interest payment period	Mar. 31, 2018
New Tranche Term Loan Agreement [Member]
Debt Instrument [Line Items]
Available revolving line of credit				$ 30,000,000
Term loan agreement terms				the Company may borrow up to an additional $30.0 million on or before March 31, 2015 at the same interest rate and on the same key terms as the Amended and Restated Term Loan Agreement
Silicon Valley Bank [Member]
Debt Instrument [Line Items]
Bridge loan							$ 5,000,000
Silicon Valley Bank Term Loan [Member] \| Series D Preferred Stock [Member]
Debt Instrument [Line Items]
Interest rate				4.00%
Loan final payment				$ 300,000
Loan fee				$ 200,000
Accrued interest payments due monthly				The term loan accrued interest at an annual rate of 4%, with principal and accrued interest payments due monthly throughout the 24 month term.
Warrants issued to purchase common stock				102,270
Exercise price per share				$ 4.40
Conversion of warrants to common shares		61,033
Weighted average exercise price of common stock		$ 7.37

Loan and Warrant Agreements - Future Minimum Principal Payments Under Term Loan Agreement (Detail) $ in Thousands	Dec. 31, 2014 USD ($)
Long Term Debt By Maturity [Abstract]
2018	$ 11,250
2019	15,000
Thereafter	3,750
Total	30,000
Notes payable, net of current portion	$ 30,000

Stockholders' Equity (Deficit) - Additional Information (Detail) - USD ($)			1 Months Ended	12 Months Ended
	Jan. 01, 2015	Jan. 02, 2014	Nov. 30, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Oct. 31, 2013
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Preferred stock, shares authorized				5,000,000	5,000,000
Proceeds from initial public offering					$ 125,040,000
Net proceeds from additional issuance of stock				$ 3,664,000	$ 2,575,000	$ 35,000
Common stock, shares outstanding				22,926,000	22,926,000
Common stock, shares authorized				100,000,000	100,000,000
Common stock reserved for future issuance				8,537,488
Options, Granted				760,639	4,430,214
Number of shares available for outstanding				5,011,063	4,539,616	135,902
Stock-based compensation cost				$ 200,000	$ 300,000
Unamortized compensation expense				$ 24,700,000
Share-based compensation expense remaining vesting term				2 years 8 months 12 days
Stock-based compensation expenses				$ 14,995,000	4,456,000	$ 246,000
Expected dividend yield				0.00%
Cash dividend				$ 0
Selling, general & administrative [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expenses				11,886,000	3,583,000	$ 148,000
Non-employees [Member] \| Selling, general & administrative [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock-based compensation expenses				$ 300,000	$ 100,000
Restricted Common Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Issuance of restricted common stock							23,872
Proceeds from the issuance of restricted common stock							$ 200,000
Number of vested restricted common stock			11,935
Employee Stock Option
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period of remaining stock				3 years
Expected dividend yield				0.00%	0.00%	0.00%
Employee Stock Option \| First Anniversary of Vesting Date [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock vested percentage				25.00%
ESPP [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Increase in common stock reserve for issuance		229,256
Number of shares available for grant				533,866
Issuance of common stock available for grant				556,000
Purchase of common stock under ESPP				251,390
Common stock reserved for issuance description				The number of shares of common stock reserved for issuance increases on January 1 of each calendar year, from January 1, 2014 through January 1, 2023, by the least of (a) one percent (1%) of the number of Shares issued and outstanding on the immediately preceding December 31, or (b) such lesser number of Shares as determined by the Administrator.
Maximum percentage that employee can contribute for purchase of common stock				15.00%
Offering Period				2 years
Purchase Period				four six-month
Expected dividend yield				0.00%	0.00%
ESPP [Member] \| Date of Offering [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Purchase price of common stock on date of purchase				85.00%
ESPP [Member] \| Date of Purchase [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Purchase price of common stock on date of purchase				85.00%
ESPP [Member] \| Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of common stock reserve for issuance to be increased								1.00%
Subsequent Event [Member] \| ESPP [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Increase in common stock reserve for issuance	236,547
IPO [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares offered for public offering			8,000,000
Shares offering price per share			$ 15.00
Proceeds from initial public offering			$ 108,300,000
Additional shares issued to underwriters			1,200,000
Net proceeds from additional issuance of stock			$ 16,700,000
Converted number of common stock			13,403,747
Conversion of warrants to common shares			1,171,352
Convertible Preferred Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Preferred stock, shares authorized					5,000,000
Common Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock, shares outstanding				23,654,745
Common Stock, voting rights				1
Common stock, shares authorized				100,000,000
2006 Stock Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved for future issuance				2,685,605
Options, Granted				0
Number of shares available for grant				5,011,063
Number of shares available for outstanding				5,011,063
2006 Stock Incentive Plan [Member] \| Employee Stock Option
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Maximum term of stock options				10 years
2013 Stock Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved for future issuance				1,985,982				4,809,000
Number of shares available for grant				5,011,063
Number of shares available for outstanding				5,011,063
2013 Stock Incentive Plan [Member] \| Employee Stock Option
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Maximum term of stock options				10 years
2013 Stock Incentive Plan [Member] \| Subsequent Event [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Increase in common stock reserve for issuance	946,189

Stockholders' Equity (Deficit) - Summary of Stock Option Transactions for 2006 Plan and 2013 Plan (Detail) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Stockholders Equity Note [Abstract]
Options, Outstanding at beginning of period	4,539,616	135,902
Options, Granted	760,639	4,430,214
Options, Exercised	(143,779)	(9,913)
Options, Canceled/forfeited/expired	(145,413)	(16,587)
Options, Outstanding at end of period	5,011,063	4,539,616	135,902
Options, Vested and expected to vest at December 31, 2014	4,943,856
Options, Exercisable at December 31, 2014	2,322,666
Weighted-Average Exercise Price, Outstanding at beginning of period	$ 8.07	$ 12.33
Weighted-Average Exercise Price, Granted	21.26	7.92
Weighted-Average Exercise Price, Exercised	2.26	6.65
Weighted-Average Exercise, Canceled/forfeited/expired	12.10	4.71
Weighted-Average Exercise Price, Outstanding at end of period	10.20	$ 8.07	$ 12.33
Weighted-Average Exercise Price, Vested and expected to vest at December 31, 2014	10.15
Weighted-Average Exercise Price, Exercisable at December 31, 2014	$ 5.86
Weighted-Average Remaining Contractual Life, Outstanding	8 years 7 months 13 days	9 years 5 months 27 days	7 years 7 days
Weighted-Average Contractual Life, Vested and expected to vest at December 31, 2014	8 years 7 months 13 days
Weighted-Average Contractual Life, Exercisable at December 31, 2014	8 years 3 months 26 days
Aggregate Intrinsic Value, Outstanding at beginning period	$ 80,369
Aggregate Intrinsic Value, Exercised	1,959	$ 118
Aggregate Intrinsic Value, Outstanding at end of period	23,534	$ 80,369
Aggregate Intrinsic Value, Vested and expected to vest at December 31, 2014	23,385
Aggregate Intrinsic Value, Exercisable at December 31, 2014	$ 17,590

Stockholders' Equity (Deficit) - Summary of Compensation Cost Included in Statement of Operations (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation cost	$ 14,995	$ 4,456	$ 246
Cost of sales [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation cost	1,317	204	36
Selling, general & administrative [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation cost	11,886	3,583	148
Research and development [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation cost	$ 1,792	$ 669	$ 62

Stockholders' Equity (Deficit) - Schedule of Assumptions Used in Black-Scholes Option-Pricing Model (Detail) - $ / shares	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected dividend yield	0.00%
Employee Stock Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average grant date fair value (per share)	$ 14.29	$ 7.52	$ 15.60
Risk-free interest rate	1.80%	1.40%	1.10%
Expected dividend yield	0.00%	0.00%	0.00%
Expected volatility	76.30%	79.00%	70.20%
Expected term (in years)	5 years 10 months 24 days	5 years 9 months 18 days	6 years
ESPP [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average grant date fair value (per share)	$ 6.86	$ 6.50
Risk-free interest rate	0.30%	0.20%
Expected dividend yield	0.00%	0.00%
Expected volatility	50.00%	66.30%
Expected term (in years)	1 year 3 months 18 days	1 year 3 months 18 days

Stockholders' Equity (Deficit) - Schedule of Shares of Common Stock Reserved for Future Issuance (Detail)	Dec. 31, 2014 shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved for future issuance	8,537,488
Common stock warrants outstanding [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved for future issuance	1,006,577
Stock options issued and outstanding [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved for future issuance	5,011,063
Authorized for future option grants [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved for future issuance	1,985,982
Employee stock purchase plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common stock reserved for future issuance	533,866

Income Taxes - Schedule of Components of Income Tax Expense (Benefit) (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Income Tax Disclosure [Abstract]
Tax at federal statutory rate	$ (27,065)	$ (21,467)	$ (11,225)
State income tax, net of federal benefit	(3,912)	(2,784)	(1,793)
Nondeductible convertible notes payable		3	617
Warrants revaluation		3,061	(869)
Research and development credits	(646)	(649)	209
Stock-based compensation	1,973	831	82
Other	355	(39)	73
Change in valuation allowance	29,366	$ 21,044	$ 12,906
Income tax expense (benefit)	$ 71

Income Taxes - Schedule of Deferred Tax Assets and Liabilities (Detail) - USD ($) $ in Thousands	Dec. 31, 2014	Dec. 31, 2013
Deferred tax assets:
Net operating loss (NOL)	$ 69,600	$ 47,996
Research and development tax credits	2,934	2,349
Capitalized R&D	10,750	7,686
Deferred rent	154	119
Stock-based and Accrued Compensation	6,481	2,490
Other	3,272	3,188
Total gross deferred tax assets	93,191	63,828
Less valuation allowance	$ (93,191)	$ (63,828)

Income Taxes - California NOL Carry Forwards Expiration (Detail) - California [Member] $ in Thousands	Dec. 31, 2014 USD ($)
Operating Loss Carryforwards [Line Items]
2016	$ 624
2017	2,052
Thereafter	$ 106,758

Income Taxes - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013
Income Tax Disclosure [Line Items]
Accumulated federal net operating loss carryforwards	$ 177,200
Accumulated state net operating loss carryforwards	190,600
Research and development tax credits	$ 2,934	$ 2,349
Deferred Tax Assets Tax Credit Carryforwards Research Expiration Year	2028
Evaluation of tax position, description	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 derive 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.
Unrecognized tax benefits	$ 3,000
Accrual interest and penalties	$ 0	0
United States Research and Development Tax Credit [Member]
Income Tax Disclosure [Line Items]
Tax Credit Carryforward, Amount		$ 400
Minimum [Member]
Income Tax Disclosure [Line Items]
Income tax Realization	50.00%
Federal [Member]
Income Tax Disclosure [Line Items]
Research and development tax credits	$ 2,800
Tax credit carryforward, expiration date	2026
California [Member]
Income Tax Disclosure [Line Items]
Research and development tax credits	$ 3,200
State and Local [Member]
Income Tax Disclosure [Line Items]
Tax credit carryforward, expiration date	2016

Income Taxes - Schedule of Unrecognized Tax Benefits (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Income Tax Disclosure [Abstract]
Gross unrecognized tax benefits at the beginning of the year	$ 1,912	$ 1,422	$ 779
Increases related to current year positions	476	349	176
Increases related to prior year positions	1,151	141	467
Gross unrecognized tax benefits at the end of the year	$ 3,539	$ 1,912	$ 1,422

Collaborations - Additional Information (Detail) $ in Thousands	12 Months Ended
	Dec. 31, 2014 USD ($) Milestone $ / IntegratedSystem	Dec. 31, 2013 USD ($)	Dec. 31, 2012 USD ($)	Sep. 30, 2016 USD ($)
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Research and development	$ 15,791	$ 11,079	$ 9,009
Restricted cash	2,000	2,050
DexCom Agreement [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Research and development	32	95	39
Additional research and development expense upon FDA approval	1,000
Milestone payment	$ 1,000
Number of additional milestone payments \| Milestone	1
Reimbursement of development costs	$ 1,000		$ 1,000
Reimbursed development costs	200
Additional payment upon achievement of milestones	$ 1,000
Royalty payable \| $ / IntegratedSystem	100
JDRF Agreement [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Research and development offset cumulative amount	$ 400
Aggregate amount of milestone payment achievements	700
Research and development offset amount	200	200
Restricted cash	$ 0	$ 0
JDRF Agreement [Member] \| Scenario Forecast [Member] \| Maximum [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Research and development offset cumulative amount				$ 3,000

Employee-Benefits - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013
Defined Benefit Plans And Other Postretirement Benefit Plans Table Text Block [Line Items]
Minimum age of employees for defined contribution plan	18 years
Total assets	$ 66,156	$ 120,207
Total liabilities	58
Deferred compensation [Member]
Defined Benefit Plans And Other Postretirement Benefit Plans Table Text Block [Line Items]
Total liabilities	58
Mutual funds held for nonqualified deferred compensation plan participants [Member]
Defined Benefit Plans And Other Postretirement Benefit Plans Table Text Block [Line Items]
Total assets	$ 58

Commitments and Contingencies - Additional Information (Detail) $ in Millions			1 Months Ended	12 Months Ended
	Nov. 05, 2013 USD ($)	Mar. 31, 2012 USD ($)	Jan. 31, 2013	Dec. 31, 2014 USD ($) LegalProceeding	Dec. 31, 2013 USD ($) LegalProceeding	Dec. 31, 2012 USD ($)
Operating Leased Assets [Line Items]
Regulatory proceedings \| LegalProceeding				0	0
Lease agreement expiration period			Jan. 31, 2015
Noncancelable Operating Lease Agreement Due On May 2017
Operating Leased Assets [Line Items]
Monthly rent payments under operating leases		$ 0.1
Tenant improvement allowances received under operating lease		2.0
Unsecured standby letter of credit		$ 0.4
Lease agreement expiration period		Aug. 31, 2017
Deferred rent arising from rent escalations and lease incentives				$ 3.4	$ 2.3
Rent expense				$ 2.1	$ 1.1	$ 0.9
Noncancelable Operating Lease Agreement Due On 2019
Operating Leased Assets [Line Items]
Tenant improvement allowances received under operating lease	$ 1.6
Unsecured standby letter of credit	$ 0.5
Lease agreement expiration period	Jul. 14, 2019

Commitments and Contingencies - Schedule of Future Minimum Payments Under Noncancelable Operating Leases (Detail) $ in Thousands	Dec. 31, 2014 USD ($)
Commitments And Contingencies Disclosure [Abstract]
2015	$ 2,555
2016	2,815
2017	2,924
2018	3,024
2019	1,275
Total	$ 12,593

Selected Quarterly Financial Data (Unaudited) (Detail) - USD ($)
$ / shares in Units, $ in Thousands

3 Months Ended

12 Months Ended

Dec. 31, 2014

Sep. 30, 2014

Jun. 30, 2014

Mar. 31, 2014

Dec. 31, 2013

Sep. 30, 2013

Jun. 30, 2013

Mar. 31, 2013

Dec. 31, 2014

Dec. 31, 2013

Dec. 31, 2012

Quarterly Financial Information Disclosure [Abstract]

Revenue

$ 17,889

$ 13,513

$ 10,254

$ 8,066

$ 10,245

$ 7,776

$ 5,528

$ 5,458

$ 49,722

$ 29,007

$ 2,475

Gross profit

6,537

4,396

3,448

867

1,188

2,533

406

2,040

15,248

6,167

(1,348)

Operating expenses

24,039

23,403

21,766

21,704

17,651

14,660

14,083

9,207

90,912

55,601

31,700

Operating loss

(17,502)

(19,007)

(18,318)

(20,837)

(16,463)

(12,127)

(13,677)

(7,167)

(75,664)

(49,434)

(33,048)

Net loss

$ (18,465)

$ (19,901)

$ (19,197)

$ (21,961)

$ (23,614)

$ (13,061)

$ (15,301)

$ (11,163)

$ (79,524)

$ (63,139)

$ (33,015)

Net loss per share, basic and diluted

$ (0.78)

^[1]

$ (0.85)

^[1]

$ (0.83)

^[1]

$ (0.96)

^[1]

$ (2.14)

$ (60.96)

$ (72.50)

$ (53.77)

$ (3.42)

$ (21.46)

$ (175.88)

[1]	Net loss per share is computed independently for each of the quarters presented. Therefore, the sum of the quarterly per-share calculations will not necessarily equal the annual per share calculation.

- Definition

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

+ References + Details