DexCom (DXCM) 10-K 23 Feb 16 2015 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($)	12 Months Ended
	Dec. 31, 2015	Feb. 18, 2016	Jun. 30, 2015
Entity Information [Line Items]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2015
Document Fiscal Year Focus	2,015
Document Fiscal Period Focus	FY
Trading Symbol	DXCM
Entity Registrant Name	DEXCOM INC
Entity Central Index Key	1,093,557
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	Yes
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		81,740,827
Entity Public Float			$ 6,284,835,598

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Current assets:
Cash and cash equivalents	$ 86.1	$ 71.8
Short-term marketable securities, available-for-sale	29.1	11.8
Accounts receivable, net	74.1	42.4
Inventory	35.2	16
Prepaid and other current assets	6.8	3.9
Total current assets	231.3	145.9
Property and equipment, net	54.7	31.2
Restricted cash	0	1
Intangible assets, net	2.2	2.7
Goodwill	3.7	3.2
Other assets	0.1	0.6
Total assets	292	184.6
Current liabilities:
Accounts payable and accrued liabilities	38.9	20.4
Accrued payroll and related expenses	24.9	17.2
Secured Debt, Current	2.3	2.3
Current portion of deferred revenue	0.8	0.7
Total current liabilities	66.9	40.6
Other liabilities	3.9	1.5
Secured Long-term Debt, Noncurrent	0	2.3
Total liabilities	$ 70.8	$ 44.4
Commitments and contingencies (Note 4)
Stockholders' equity:
Preferred stock, $0.001 par value, 5.0 shares authorized; no shares issued and outstanding at December 31, 2015 and December 31, 2014, respectively	$ 0	$ 0
Common stock, $0.001 par value, 100.0 authorized; 82.0 and 81.7 issued and outstanding, respectively, at December 31, 2015; and 77.6 and 77.3 shares issued and outstanding, respectively, at December 31, 2014	0.1	0.1
Additional paid-in capital	776.8	638
Accumulated other comprehensive loss	(0.3)	(0.1)
Accumulated deficit	(555.4)	(497.8)
Total stockholders' equity	221.2	140.2
Total liabilities and stockholders' equity	$ 292	$ 184.6

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 2015	Dec. 31, 2014
Statement of Financial Position [Abstract]
Preferred Stock, Par or Stated Value Per Share	$ 0.001	$ 0.001
Preferred Stock, Shares Authorized	5,000,000	5,000,000
Preferred stock, shares issued (in shares)	0
Preferred stock, shares outstanding (in shares)	0
Common Stock, Par or Stated Value Per Share	$ 0.001	$ 0.001
Common stock, shares authorized (in shares)	100,000,000	100,000,000
Common Stock, Shares, Issued	82,000,000	77,600,000
Balance, Shares	81,700,000	77,300,000

Consolidated Statements of Oper

Consolidated Statements of Operations - USD ($) shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Product revenue	$ 400.7	$ 257.1	$ 157.1
Development grant and other revenue	1.3	2.1	2.9
Total Revenue	402	259.2	160
Product cost of sales	123.6	82.3	58.1
Development and other cost of sales	0	0.6	1.8
Total cost of sales	123.6	82.9	59.9
Gross profit	278.4	176.3	100.1
Operating expenses
Research and development	137.5	69.4	44.8
Selling, general and administrative	198	128.4	84.2
Total operating expenses	335.5	197.8	129
Operating loss	(57.1)	(21.5)	(28.9)
Interest expense	(0.4)	(0.8)	(0.9)
Loss before income taxes	(57.5)	(22.3)	(29.8)
Income tax expense	(0.1)	(0.1)	0
Net loss	$ (57.6)	$ (22.4)	$ (29.8)
Basic and diluted net loss per share	$ (0.72)	$ (0.30)	$ (0.42)
Shares used to compute basic and diluted net loss per share	79.8	75.2	71.1

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Loss - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Net loss	$ (57,600)	$ (22,400)	$ (29,800)
Unrealized gain (loss) on short-term available-for-sale marketable securities	0	0	0
Foreign currency translation gain (loss)	(200)	0	0
Comprehensive loss	(57,800)	(22,400)	(29,800)
Accumulated deficit [Member]
Net loss	$ (57,600)	$ (22,400)	$ (29,800)

CONSOLIDATED STATEMENTS OF STOC

CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (DEFICIT) - USD ($) $ in Millions	Total	Common stock [Member]	Additional paid-in capital [Member]	Accumulated other comprehensive income (loss) [Member]	Accumulated deficit [Member]	Verily Life Sciences [Member]Common stock [Member]	Verily Life Sciences [Member]Additional paid-in capital [Member]
Balance at Dec. 31, 2012	$ 77	$ 0.1	$ 522.6	$ (0.1)	$ (445.6)
Balance, shares at Dec. 31, 2012		69,500,000
Issuance of common stock under equity incentive plans, shares		2,800,000
Issuance of common stock under equity incentive plans	$ 10.2		10.2
Issuance of common stock for Employee Stock Purchase Plan, shares	199,661	200,000
Issuance of common stock for Employee Stock Purchase Plan	$ 1.9		1.9
Other Significant Noncash Transaction, Value of Sweetspot Contingent Conisederation Settlement	0
Share-based compensation for employee stock options and award grants	24.8		24.8
Net loss	(29.8)				(29.8)
Balance at Dec. 31, 2013	84.1	$ 0.1	559.5	(0.1)	(475.4)
Balance, shares at Dec. 31, 2013		72,500,000
Issuance of common stock under equity incentive plans, shares		4,600,000
Issuance of common stock under equity incentive plans	$ 21.4		21.4
Issuance of common stock for Employee Stock Purchase Plan, shares	135,057	100,000
Issuance of common stock for Employee Stock Purchase Plan	$ 2.6		2.6
Issuance of common stock for SweetSpot acquisition and milestone, shares		100,000
Other Significant Noncash Transaction, Value of Sweetspot Contingent Conisederation Settlement	4		4
Share-based compensation for employee stock options and award grants	50.5		50.5
Net loss	(22.4)				(22.4)
Balance at Dec. 31, 2014	140.2	$ 0.1	638	(0.1)	(497.8)
Balance, shares at Dec. 31, 2014		77,300,000
Issuance of common stock under equity incentive plans, shares		3,900,000
Issuance of common stock under equity incentive plans	$ 15.3		15.3
Issuance of common stock for Employee Stock Purchase Plan, shares	115,848	100,000
Issuance of common stock for Employee Stock Purchase Plan	$ 3.8		3.8
Issuance of common stock related to Verily Collaboration Agreement, shares						400,000
Issuance of common stock related to Verily Collaboration Agreement	36.5						$ 36.5
Other Significant Noncash Transaction, Value of Sweetspot Contingent Conisederation Settlement	0
Share-based compensation for employee stock options and award grants	83.2		83.2
Net loss	(57.6)				(57.6)
Other comprehensive loss	(0.2)
Balance at Dec. 31, 2015	$ 221.2	$ 0.1	$ 776.8	$ (0.3)	$ (555.4)
Balance, shares at Dec. 31, 2015		81,700,000

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Operating activities
Net loss	$ (57.6)	$ (22.4)	$ (29.8)
Adjustments to reconcile net loss to cash used in operating activities:
Depreciation and amortization	10.8	8.4	7
Share-based compensation	82.7	50	24.6
Non-cash research and development charge through issuance of common stock	36.5	0	0
Accretion and amortization related to marketable securities, net	0.3	0.1	0.3
Amortization of debt issuance costs	0.2	0.3	0.4
Change in fair value of contingent consideration	0	(0.2)	2.5
Other non-cash expenses	0.5	0.2	0.2
Changes in operating assets and liabilities:
Accounts receivable	(31.7)	(16.3)	(6.5)
Inventory	(19.2)	(7)	(1.6)
Prepaid and other assets	(2.5)	(0.4)	(1.4)
Restricted cash	1	0	0
Accounts payable and accrued liabilities	17.8	8.3	2.4
Accrued payroll and related expenses	7.7	2.2	5.8
Deferred revenue	0.1	0	(1.2)
Deferred rent and other liabilities	2.4	0.4	(0.3)
Net Cash Provided by (Used in) Operating Activities	49	23.6	2.4
Investing activities
Purchase of available-for-sale marketable securities	(45.2)	(13.8)	(16.3)
Proceeds from the maturity of available-for-sale marketable securities	27.5	13.2	45.1
Purchase of property and equipment	(33.3)	(16.2)	(7.9)
Acquisitions, net of cash acquired	(0.5)	0	0
Net cash provided by (used in) investing activities	(51.5)	(16.8)	20.9
Financing activities
Net proceeds from issuance of common stock	19.1	24	12
Repayment of long-term debt	(2.3)	(2.2)	(0.2)
Net cash provided by financing activities	16.8	21.8	11.8
Increase in cash and cash equivalents	14.3	28.6	35.1
Cash and cash equivalents, beginning of period	71.8	43.2	8.1
Cash and cash equivalents, ending of period	86.1	71.8	43.2
Supplemental disclosure of non-cash transactions
Other Significant Noncash Transaction, Value of Sweetspot Contingent Conisederation Settlement	0	4	0
Interest Paid	$ 0.3	$ 0.4	$ 0.5

Organization and Summary of Sig

Organization and Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2015
Disclosure Organization And Summary Of Significant Accounting Policies Additional Information [Abstract]
Organization and Summary of Significant Accounting Policies	Organization and Summary of Significant Accounting Policies Organization and Business DexCom, Inc. is a medical device company focused on the design, development and commercialization of continuous glucose monitoring (“CGM”) systems for ambulatory use by people with diabetes and by healthcare providers in the hospital for the treatment of people with and without diabetes. Unless the context requires otherwise, the terms “we,” “us,” “our,” the “company,” or “DexCom” refer to DexCom, Inc. and its subsidiaries. Basis of Presentation We have incurred operating losses since our inception and have an accumulated deficit of $555.4 million at December 31, 2015 . As of December 31, 2015 , we had available cash, cash equivalents and short-term marketable securities totaling $115.2 million and working capital of $164.4 million . Our ability to transition to, and maintain, profitable operations is dependent upon achieving a level of revenues adequate to support our cost structure. If events or circumstances occur such that we do not meet our operating plan as expected, we may be required to reduce planned increases in compensation expenses and other operating expenses needed to support the growth of our business which could have an adverse impact on our ability to achieve our intended business objectives. We believe our working capital resources will be sufficient to fund our operations through at least December 31, 2016 . Principles of Consolidation The consolidated financial statements include the accounts of DexCom and our wholly owned subsidiaries, DexCom AB, and SweetSpot Diabetes Care, Inc. (“SweetSpot”). All significant intercompany balances and transactions have been eliminated in consolidation. Segment Reporting and Geographic Information An operating segment is identified as a component of a business that has discrete financial information available, and one for which the chief operating decision maker must decide the level of resource allocation. In addition, the guidance for segment reporting indicates certain quantitative thresholds. The operations of SweetSpot, our subsidiary, does not meet the definition of an operating segment and are currently not material, but may become material in the future. We currently consider our operations to be, and manage our business globally within, one reportable segment, which is consistent with how our President and Chief Executive Officer, who is our chief operating decision maker, reviews our business, makes investment and resource allocation decisions and assesses operating performance. We sell our products through a direct sales force in the United States and through distribution arrangements in the United States, Canada, Australia, New Zealand, and in portions of Europe, Asia, the Middle East, Latin America, and Africa. DexCom, Inc. is domiciled in the United States. During the years ended 2015 , 2014 and 2013 , no individual country, outside of our country of domicile, generated revenue that represented more than 10% of our total revenue. Product revenue is designated based on the geographic location to which we deliver the product. Development grant and other revenue is attributed to countries based upon the location of the headquarters of our customer or their billing address. During fiscal 2015 and 2014 , total revenues attributable to the United States and outside of the United States were as follows: Years Ended December 31, 2015 2014 Amount % Amount % (In millions, except percentages) Revenues: United States $ 347.4 86 % $ 224.2 86 % Outside of the United States 54.6 14 % 35.0 14 % Total $ 402.0 100 % $ 259.2 100 % Revenue attributed to countries outside of the United States for fiscal 2013 did not exceed 10% of our total revenue. Substantially all of our long-lived assets are located in the United States. Use of Estimates The preparation of consolidated financial statements in conformity with U.S. GAAP requires us to make estimates and assumptions that affect the amounts reported in the consolidated financial statements and accompanying notes. Actual results could differ from these estimates. Significant estimates include excess or obsolete inventories, valuation of inventory, warranty accruals, allowance for bad debt, refunds and rebates, including pharmacy rebates and share­based compensation expense. Cash and Cash Equivalents We invest our excess cash in bank deposits, money market accounts, and debt securities. We consider all highly liquid investments with a maturity of 90 days or less at the time of purchase to be cash equivalents. 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. Uncollectible accounts are written-off against the allowance after appropriate collection efforts have been exhausted and when it is deemed that a customer account is uncollectible. Generally, receivable balances greater than one year past due are deemed uncollectible. Letters of Credit At December 31, 2015 and 2014 , we had irrevocable letters of credit outstanding with a commercial bank for approximately $0.7 million and $0.7 million , respectively, securing our facility leases. The letters of credit are secured by cash equivalents. The letter of credit as of December 31, 2014 was also secured by an equal amount of restricted cash which has been separately disclosed in the accompanying consolidated balance sheets. Concentration of Credit Risk Financial instruments which potentially subject us to concentrations of credit risk consist primarily of cash, cash equivalents, short-term investment securities, and accounts receivable. We limit our exposure to credit loss by placing our cash with high credit quality financial institutions. We have established guidelines relative to diversification of our cash and investment securities and their maturities that are intended to secure safety and liquidity. These guidelines are periodically reviewed and modified to take advantage of trends in yields and interest rates and changes in our operations and financial position. The following table summarizes customers who accounted for 10% or more of net accounts receivable: December 31, 2015 2014 Customer A 23% 23% Customer B 13% 12% Impairment of Long-Lived Assets We record impairment losses on long-lived assets used in operations when events and circumstances indicate that assets might be impaired and the undiscounted cash flows estimated to be generated by those assets are less than the carrying amount of those assets. We have not experienced any material impairment losses on assets used in operations. Share-Based Compensation Share-based compensation expense is measured at the grant date based on the estimated fair value of the award and is recognized, for awards that are ultimately expected to vest, primarily on a straight-line basis over the requisite service period of the individual grants, which typically equals the vesting period. The fair value of our RSUs is based on the market price of our common stock on the date of grant. We are also required to estimate at grant the likelihood that the award will ultimately vest (the “pre-vesting forfeiture rate”), and to revise the estimate, if necessary, in future periods if the actual forfeiture rate differs. We determine the pre-vesting forfeiture rate of an award based on our historical pre-vesting award forfeiture experience, giving consideration to company-specific events impacting historical pre-vesting award forfeiture experience that are unlikely to occur in the future as well as anticipated future events that may impact forfeiture rates. We use our historical data to estimate pre-vesting forfeitures and record stock-based compensation expense only for those awards that are expected to vest. Revenue Recognition We sell our durable systems and disposable units through a direct sales force in the United States and through distribution arrangements in the United States , Canada , Australia , New Zealand , and in portions of Europe , Asia , the Middle East , Latin America and Africa . Components are individually priced and can be purchased separately or together. We receive payment directly from customers who use our products, as well as from distributors, organizations and third-party payors. Our durable system includes a reusable transmitter, a receiver, a power cord and a USB cable. Disposable sensors for use with the durable system are sold separately in packages of four. We provide free of charge software and mobile applications for use with our durable systems and disposable sensors. The initial durable system price is generally not dependent upon the purchase of any amount of disposable sensors. Revenue is recognized when persuasive evidence of an arrangement exists, delivery has occurred or services have been rendered, the price is fixed or determinable, and collectability is reasonably assured. Revenue on product sales is generally recognized upon shipment, which is when title and the risk of loss have been transferred to the customer and there are no other post shipment obligations. With respect to customers who directly pay for products, the products are generally paid for at the time of shipment using a customer’s credit card and do not include customer acceptance provisions. We recognize revenue from contracted insurance payors based on the contracted rate. For non-contracted insurance payors, we obtain prior authorization from the payor and recognize revenue based on the estimated collectible amount and historical experience. We also receive a prescription or statement of medical necessity and, for insurance reimbursement customers, an assignment of benefits prior to shipment. We provide a “ 30 -day money back guarantee” program whereby customers who purchase a durable system and a package of four disposable sensors may return the durable system for any reason within thirty days of purchase and receive a full refund of the purchase price of the durable system. We accrue for estimated returns, refunds and rebates, including pharmacy rebates, by reducing revenues and establishing a liability account at the time of shipment based on historical experience. Returns have historically been immaterial. Allowances for rebates include contracted discounts with commercial payors and are amounts owed after the final dispensing of the product by a distributor or retail pharmacy to a pharmacy benefit plan participant and are based upon contractual agreements with private sector benefit providers. The allowance for rebates is based on contractual discount rates, expected utilization under each contract and our estimate of the amount of inventory in the distribution channel that will become subject to such rebates. Our estimates for expected utilization for rebates are based on historical rebate claims and to a lesser extent third party market research data. Rebates are generally invoiced and paid monthly or quarterly in arrears so that our accrual consists of an estimate of the amount expected to be incurred for the current month's or quarter’s activity, plus an accrual for unpaid rebates from prior periods, and an accrual for inventory in the distribution channel. We have entered into distribution agreements with Byram , Edgepark and other distributors that allow the distributors to sell our durable systems and disposable units. We have contracts with certain distributors who stock our products, and we refer to these distributors as Stocking Distributors , whereby the Stocking Distributors fulfill orders for our product from their inventory. We also have contracts with certain distributors that do not stock our products, but rather products are shipped directly to the customer by us on behalf of our distributor, and we refer to these distributors as Drop-Ship Distributors. Revenue is recognized based on contracted prices and invoices are either paid by check following the issuance of a purchase order or letter of credit, or they are paid by wire at the time of placing the order. Terms of distributor orders are generally FOB (or Free Carrier (“ FCA ”) shipping point for international orders). Distributors do not have rights of return per their distribution agreement outside of our standard warranty. The distributors typically have a limited time frame to notify us of any missing, damaged, defective or non-conforming products. For any such products, we shall either, at our option, replace the portion of defective or non-conforming product at no additional cost to the distributor or cancel the order and refund any portion of the price paid to us at that time for the sale in question. One of our distributors, Byram , accounted for $74.1 million , $46.1 million and $24.3 million in gross revenue, which represents 18% , 18% and 15% of our total revenues for the twelve months ended December 31, 2015 , 2014 and 2013 , respectively. Another one of our distributors, Edgepark , accounted for $42.6 million , $28.1 million and $23.1 million in gross revenue, which represents 11% , 11% and 14% of our total revenues for the twelve months ended December 31, 2015 , 2014 and 2013 , respectively. Warranty Accrual Estimated warranty costs associated with a product are recorded at the time of shipment. We estimate future warranty costs by analyzing historical warranty experience for the timing and amount of returned product, and these estimates are evaluated on at least a quarterly basis to determine the continued appropriateness of such assumptions. Research and Development All costs of research and development are expensed as incurred. Research and development expenses primarily include salaries, bonus and payroll related costs, clinical trials, regulatory expenses, quality assurance programs, part components, share-based compensation, and fees paid to consultants. Foreign Currency The financial statements of our subsidiary in Sweden, whose functional currency is the Swedish Krona, are translated into U.S. dollars for financial reporting purposes. Assets and liabilities are translated at period-end exchange rates, and revenue and expense transactions are translated at average exchange rates for the period. Cumulative translation adjustments are recognized as part of comprehensive income and are included in accumulated other comprehensive loss in the consolidated balance sheet. Gains and losses on transactions denominated in other than the functional currency are reflected in operations. To date the results of operations of this subsidiary and related translation adjustments have not been material in our consolidated results. Comprehensive Loss We report all components of comprehensive loss, including net loss, in the consolidated 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. Net loss and comprehensive loss, including unrealized gains and losses on marketable securities and foreign currency translation adjustments, are reported, net of their related tax effect, to arrive at comprehensive loss. Inventory Inventory is valued at the lower of cost or market value on a part-by-part basis that approximates first in, first out. We make adjustments to reduce the cost of inventory to its net realizable value, if required, for estimated excess, obsolete and potential scrapped inventories. Factors influencing these adjustments include inventories on hand and on order compared to estimated future usage and sales for existing and new products, as well as judgments regarding quality control testing data, and assumptions about the likelihood of scrap and obsolescence. Once written down the adjustments are considered permanent and are not reversed until the related inventory is sold or disposed. Our products require customized products and components that currently are available from a limited number of sources. We purchase certain components and materials from single sources due to quality considerations, costs or constraints resulting from regulatory requirements. Deferred Rent Rent expense is recorded on a straight-line basis over the term of the lease. The difference between rent expense accrued and amounts paid under the lease agreement is recorded as deferred rent in the accompanying consolidated balance sheets. Income Taxes We account for income taxes under the asset and liability method, which requires the recognition of deferred tax assets and liabilities for the expected future tax consequences of events that have been included in the financial statements. Under this method, we determine deferred tax assets and liabilities on the basis of the differences between the financial statement and tax bases of assets and liabilities by using enacted tax rates in effect for the year in which the differences are expected to reverse. The effect of a change in tax rates on deferred tax assets and liabilities is recognized in income in the period that includes the enactment date. We recognize deferred tax assets to the extent that we believe that these assets are more likely than not to be realized, which requires significant judgment. We establish a valuation allowance against our net deferred tax assets to reduce them to the amount expected to be realized. The realization of deferred tax assets is dependent, in part, upon future taxable income. In assessing whether our deferred tax assets will be realized, we consider all available evidence, both positive and negative. Such evidence includes historical earnings, future reversals of existing taxable temporary differences, estimates of future taxable income, and the feasibility of ongoing tax planning strategies. We record uncertain tax positions in accordance with ASC 740 on the basis of a two-step process in which (1) we determine whether it is more likely than not that the tax positions will be sustained on the basis of the technical merits of the position and (2) for those tax positions that meet the more-likely-than-not recognition threshold, we recognize the largest amount of tax benefit that is more than 50 percent likely to be realized upon ultimate settlement with the related tax authority. We file income tax returns in the United States, Sweden and in various state jurisdictions with varying statutes of limitations. Due to net operating losses incurred, our income tax returns from inception to date are subject to examination by taxing authorities. Our policy is to recognize interest expense and penalties related to income tax matters as a component of income tax expense. As of December 31, 2015 , we had no interest or penalties accrued for uncertain tax positions. Marketable Securities We have classified our marketable securities with remaining maturity at purchase of more than three months and remaining maturities of one year or less as short-term available-for-sale marketable securities. Marketable securities with remaining maturities of greater than one year are also classified as short-term available-for-sale marketable securities as such marketable securities represent the investment of cash that is available for current operations. We carry our marketable securities at fair value with unrealized gains and losses, if any, reported as a separate component of stockholders' equity and included in comprehensive loss. Realized gains and losses are calculated using the specific identification method and recorded as interest income. We invest in various types of securities, including debt securities in government-sponsored entities, corporate debt securities, U.S. Treasury securities and commercial paper. We do not generally intend to sell the investments and it is not more likely than not that we will be required to sell the investments before recovery of their amortized cost bases, which may be at maturity. Fair Value Measurements The fair value hierarchy described by the authoritative guidance for fair value measurements is based on three levels of inputs, of which the first two are considered observable and the last unobservable, that may be used to measure fair value and include the following: Level 1—Quoted prices in active markets for identical assets or liabilities. Level 2—Inputs other than Level 1 that are observable, either directly or indirectly, such as quoted prices for similar assets or liabilities; quoted prices in markets that are not active; or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities. Level 3—Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets or liabilities. We carry our marketable securities at fair value. The carrying amounts of financial instruments, such as cash and cash equivalents, accounts receivable, prepaid expenses and other current assets, accounts payable and accrued liabilities, are carried at cost, which approximate the related fair values due to the short-term maturities of these instruments. For additional detail see Note 6 “Fair Value Measurements.” Property and Equipment Property and equipment is stated at cost and depreciated over the estimated useful lives of the assets, generally three years for computer equipment, four years for machinery and equipment, and five years for furniture and fixtures, using the straight-line method. Leasehold improvements are stated at cost and amortized over the shorter of the estimated useful lives of the assets or the remaining lease term. Goodwill and Intangible Assets Goodwill, which has an indefinite useful life, represents the excess of cost over fair value of net assets acquired. The change in the carrying value of goodwill during the twelve months ended December 31, 2015 resulted from an acquisition of a small privately held engineering consulting company with 10 full time employees to complement our research and development activities, which closed in April 2015. Our identifiable intangible assets are comprised of acquired technologies, customer relationships, covenants not-to-compete, in-process research and development and trade names. The cost of identifiable intangible assets with finite lives is generally amortized on a straight-line basis over the assets’ respective estimated useful lives. We test goodwill and intangible assets with indefinite lives for impairment on an annual basis. Also, between annual tests we test for impairment if events and circumstances indicate it is more likely than not that the fair value is less than the carrying value. Events that would indicate impairment and trigger an interim impairment assessment include, but are not limited to, current economic and market conditions, including a decline in market capitalization, a significant adverse change in legal factors, business climate or operational performance of the business and an adverse action or assessment by a regulator. Recent Accounting Guidance In May 2014, the Financial Accounting Standards Board ("FASB") issued authoritative guidance for Revenue from Contracts with Customers, to supersede nearly all existing revenue recognition guidance under U.S. GAAP. The core principle of the guidance is to recognize revenues when promised goods or services are transferred to customers in an amount that reflects the consideration that is expected to be received for those goods or services. The guidance defines a five step process to achieve this core principle and it is possible when the five step process is applied, more judgment and estimates may be required within the revenue recognition process than required under existing U.S. GAAP including 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 updated standard permits the use of either the retrospective or cumulative effect transition method and is effective for us in our first quarter of fiscal 2018. Early adoption is not permitted. We have not yet selected a transition method and we are currently evaluating the effect that the updated standard will have on our consolidated financial statements and related disclosures. In July 2015, the FASB issued guidance to change the subsequent measurement of inventory from lower of cost or market to lower of cost and net realizable value. The guidance requires that inventory accounted for under the first-in, first-out (FIFO) or average cost methods be measured at the lower of cost and net realizable value, where net realizable value represents the estimated selling price of inventory in the ordinary course of business, less reasonably predictable costs of completion, disposal, and transportation. The guidance is effective for us beginning in the first quarter of fiscal 2018. Earlier application is permitted as of the beginning of an interim or annual reporting period. We are currently evaluating the effect this guidance will have on our consolidated financial statements. In November 2015, the FASB issued ASU 2015-17, Balance Sheet Classification of Deferred Taxes ("ASU 2015-17"), which requires entities to present deferred tax assets and deferred tax liabilities as noncurrent in a classified balance sheet. The ASU simplifies the current guidance in ASC Topic 740, Income Taxes, which requires entities to separately present deferred tax assets and liabilities as current and noncurrent in a classified balance sheet. The current requirement that deferred tax liabilities and assets of a tax-paying component of an entity be offset and presented as a single amount is not affected by the amendments in this ASU. ASU 2015-17 is effective for fiscal years beginning after December 15, 2016, and interim periods within those annual periods, with early adoption permitted. We have elected to early adopt prospectively beginning in the year ended December 31, 2015 with our deferred tax assets and deferred tax liabilities presented as noncurrent in the consolidated balance sheet and related disclosures for the year ended December 31, 2015.

Net Loss Per Common Share

Net Loss Per Common Share	12 Months Ended
	Dec. 31, 2015
Earnings Per Share [Abstract]
Net Loss Per Common Share	Net Loss Per Common Share Basic net loss per share attributable to common stockholders is calculated by dividing the net loss attributable to common stockholders by the weighted-average number of common shares outstanding for the period, without consideration for common stock equivalents. Diluted net loss per share attributable to common stockholders is computed by dividing the net loss attributable to common stockholders by the weighted-average number of common share equivalents outstanding for the period determined using the treasury-stock method. For purposes of this calculation, outstanding options and unvested RSUs settleable in shares of common stock are considered to be common stock equivalents and are only included in the calculation of diluted net loss per share when their effect is dilutive. Historical outstanding anti-dilutive securities not included in diluted net loss per share attributable to common stockholders calculation (in millions): Years Ended December 31, 2015 2014 2013 Options outstanding to purchase common stock 1.3 3.1 5.8 Unvested restricted stock units 4.1 4.2 3.6 Total 5.4 7.3 9.4

Financial Statement Details

Financial Statement Details	12 Months Ended
	Dec. 31, 2015
Disclosure of Financial Statement Details [Abstract]
Financial Statement Details	Financial Statement Details (in millions) Short Term Marketable Securities, Available-for-Sale Short term marketable securities, consisting solely of debt securities were as follows: December 31, 2015 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Estimated Market Value U.S. government agencies $ 22.1 $ — $ — $ 22.1 Corporate debt 4.9 — — 4.9 Commercial paper 2.1 — — 2.1 Total $ 29.1 $ — $ — $ 29.1 December 31, 2014 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Estimated Market Value U.S. government agencies $ 9.1 $ — $ — $ 9.1 Corporate debt 2.3 — — 2.3 Commercial paper 0.4 — — 0.4 Total $ 11.8 $ — $ — $ 11.8 Accounts Receivable December 31, 2015 2014 Accounts receivable $ 82.0 $ 46.8 Less allowance for doubtful accounts, sales returns and discounts (7.9 ) (4.4 ) Total $ 74.1 $ 42.4 Inventory December 31, 2015 2014 Raw materials $ 16.0 $ 7.6 Work-in-process 2.6 1.0 Finished goods 16.6 7.4 Total $ 35.2 $ 16.0 Property and Equipment December 31, 2015 2014 Furniture and fixtures $ 3.7 $ 3.9 Computer equipment 21.0 18.9 Machinery and equipment 47.2 26.5 Leasehold improvements 21.0 14.7 Total 92.9 64.0 Accumulated depreciation and amortization (38.2 ) (32.8 ) Property and equipment, net $ 54.7 $ 31.2 Depreciation and amortization expense related to property and equipment for the twelve months ended December 31, 2015 , 2014 , and 2013 was $10.2 million , $7.8 million , and $6.4 million , respectively. Goodwill and Intangible Assets Goodwill and intangible assets as of December 31, 2015 consisted of the following (in millions, except months): Weighted-Average Amortization Period (in months) Gross Amount Accumulated Amortization Intangible Assets, net Intangible assets subject to amortization Developed technology 109 $ 3.2 $ (1.5 ) $ 1.7 Customer-related intangible 70 0.6 (0.4 ) 0.2 Covenants not-to-compete 70 0.2 (0.1 ) 0.1 In-process research and development 51 0.2 (0.1 ) 0.1 Total $ 4.2 $ (2.1 ) $ 2.1 Intangible assets not subject to amortization Trademarks and trade names 0.1 Goodwill 3.7 Total $ 3.8 Goodwill and intangible assets as of December 31, 2014 consisted of the following (in millions, except months): Weighted-Average Amortization Period (in months) Gross Amount Accumulated Amortization Intangible Assets, net Intangible assets subject to amortization Developed technology 109 $ 3.2 $ (1.2 ) $ 2.0 Customer-related intangible 70 0.6 (0.3 ) 0.3 Covenants not-to-compete 70 0.2 (0.1 ) 0.1 Total $ 4.0 $ (1.6 ) $ 2.4 Intangible assets not subject to amortization In-process research and development 0.2 Trademarks and trade names 0.1 Goodwill 3.2 Total $ 3.5 Total expense related to amortization of intangible assets for the twelve months ended December 31, 2015 , 2014 , and 2013 was $0.5 million , $0.6 million , and $0.6 million , respectively. In the fourth quarter of 2014 , we recorded an impairment charge of $0.2 million, included in the "Research and development" line item of the Consolidated Statement of Operations related to our Covenant not-to-compete intangible asset as a result of the SweetSpot settlement agreement entered into on November 3, 2014. The following table sets forth the total future amortization expense related to intangible assets subject to amortization as of December 31, 2015 : Fiscal Year Ending 2016 $ 0.5 2017 0.5 2018 0.3 2019 0.3 2020 0.3 Thereafter through 2021 0.2 Total $ 2.1 Accounts Payable and Accrued Liabilities December 31, 2015 2014 Accounts payable trade $ 19.0 $ 9.9 Accrued tax, audit, and legal fees 2.1 1.6 Clinical trials 0.7 0.4 Accrued other including warranty 17.1 8.5 Total $ 38.9 $ 20.4 Accrued Payroll and Related Expenses December 31, 2015 2014 Accrued paid time off $ 4.4 $ 3.2 Accrued wages, bonus and taxes 18.4 12.5 Other accrued employee benefits 2.1 1.5 Total $ 24.9 $ 17.2 Accrued Warranty Warranty costs are reflected in the consolidated statements of operations as product cost of sales. A reconciliation of our accrued warranty costs for the twelve months ended December 31, 2015 and 2014 were as follows: Years Ended December 31, 2015 2014 Beginning balance $ 1.3 $ 0.9 Charges to costs and expenses 9.0 5.2 Costs incurred (7.0 ) (4.8 ) Ending balance $ 3.3 $ 1.3

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2015
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Long-Term Debt In November 2012, we entered into a loan and security agreement (the “Loan Agreement”) that provides for (i) a $15.0 million revolving line of credit and (ii) a total term loan of up to $20.0 million (the "Term Loan"), in both cases, to be used for general corporate purposes. The borrowings under the Loan Agreement are collateralized by a first priority security interest in substantially all of our assets with a negative pledge on our intellectual property. The revolving line of credit expired as of November 2015 with no amounts drawn or outstanding. In accordance with the Loan Agreement, $7.0 million was advanced under the Term Loan at the funding date in November 2012 and the remaining $13.0 million in additional funds expired unused. The Term Loan bears a fixed interest rate equal to the three-year treasury rate at the time of advance plus 6.94% and requires payment of interest only for the first year and amortized payments of interest and principal thereafter through the maturity date of November 2016 . The aggregate debt issuance costs and fees incurred with respect to the issuance of the Loan Agreement were $1.1 million . These costs have been capitalized as debt issuance costs on our consolidated balance sheet as other assets. Fees related to the revolving line of credit were amortized through the maturity date of November 2015. Issuance costs and fees related to the term loan are being amortized through the maturity date of November 2016 using the effective interest method. As of December 31, 2015 , the remaining unamortized issuance costs and fees are insignificant. Principal repayment obligations under the Loan Agreement as of December 31, 2015 were $2.3 million . Leases Under the office lease agreement, as amended (the "Office Lease"), with John Hancock Life Insurance Company (U.S.A.) (the "Landlord") we lease approximately 219,000 square feet of space in the locations at 6340 Sequence Drive, 6310 Sequence Drive and 6290 Sequence Drive. The amended lease term extends through March 2022 and we have an option to renew the lease upon the expiration of the initial term for two additional five -year terms by giving notice to the Landlord prior to the end of the initial term of the lease and any extension period, if applicable. Provided we are not in default under the Office Lease and the Office Lease is still in effect, we generally have the right to terminate the lease starting at the 55 th month of the Office Lease. In September 2015, we received $1.8 million of tenant improvement allowance associated with the Office Lease, which was recorded as a deferred rent obligation and will be amortized over the term of the lease and reflected as a reduction to rent expense. Leasehold improvements associated with the tenant improvement allowance are included in Property and equipment, net in our consolidated balance sheet. We have also entered into other operating lease agreements, primarily for office and warehouse space, that expire at various times through March 2022. These facility leases have annual rental increases ranging from approximately 2.5% to 4% . The difference between the straight-line expense over the term of the lease and actual amounts paid are recorded as deferred rent. Rental obligations, excluding real estate taxes, operating costs, and tenant improvement allowances, under all lease agreements as of December 31, 2015 were as follows (in millions): Fiscal Year Ending 2016 $ 4.8 2017 4.4 2018 5.2 2019 5.3 2020 5.3 Thereafter 6.5 Total $ 31.5 Total rent expense for the twelve months ended December 31, 2015 , 2014 and 2013 was $5.6 million , $3.6 million and $3.0 million , respectively. Litigation From time to time, we are subject to various claims and suits arising out of the ordinary course of business, including commercial and employment related matters. In addition, from time to time, we may bring claims or initiate lawsuits against various third parties with respect to matters arising out of the ordinary course of our business, including commercial and employment related matters. We do not expect that the resolution of these matters would, or will, have a material adverse effect or material impact on our consolidated financial position. Purchase Commitments We are party to various purchase arrangements related to our manufacturing and development activities including materials used in our CGM systems. As of December 31, 2015 , we had purchase commitments with vendors totaling $49.3 million due within one year. There are no material purchase commitments due beyond one year.

Development and Other Agreement

Development and Other Agreements	12 Months Ended
	Dec. 31, 2015
Disclosure Development Agreements Additional Information [Abstract]
Development and Other Agreements	Development and Other Agreements Collaboration with Google Life Sciences On August 10, 2015, we entered into a Collaboration and License Agreement (the “ Verily Collaboration Agreement ”) with Google Life Sciences LLC , now renamed Verily Life Sciences (“ Verily ”). Pursuant to the Verily Collaboration Agreement , we and Verily have agreed to jointly develop a series of next-generation continuous glucose monitoring products. The Verily Collaboration Agreement provides us with an exclusive license to use certain intellectual property of Verily related to the development, manufacture and commercialization of the products contemplated under the Verily Collaboration Agreement . The Verily Collaboration Agreement provides for the establishment of a joint steering committee, joint development committee and joint commercialization committee to oversee and coordinate the parties’ activities under the collaboration. We and Verily have agreed to make committee decisions by consensus. The terms of Verily Collaboration Agreement required that we pay an upfront fee of $35.0 million in either cash or shares of our common stock at our sole election, with the number of shares calculated based on the volume weighted average trading price during a period of twenty consecutive trading days ending prior to the date of the Verily Collaboration Agreement . In addition, we will pay Verily up to $65.0 million in additional milestones upon achievement of various development and regulatory objectives, which payments may be paid in cash or shares of our common stock at our sole election, calculated based on the volume weighted average trading price during a period of twenty consecutive trading days ending on the trading day prior to the date on which the applicable objective has been achieved. On August 27, 2015, we filed a Registration Statement on Form S-3 with the SEC and issued 404,591 shares of our common stock to Verily in connection with the $35.0 million upfront payment. We recorded $36.5 million in research and development expense in our consolidated statement of operations for the twelve months ended months ended December 31, 2015 related to the issuance of the 404,591 shares of our common stock, based on our stock price of $90.29 per share as of the date of Verily Collaboration Agreement . In addition, Verily is eligible to receive tiered royalty payments associated with the commercialization of the products contemplated under the Verily Collaboration Agreement , which are subject to regulatory approval. Unless we attain annual product sales subject to the Verily Collaboration Agreement in excess of $750.0 million , there will be no royalty paid by us to Verily . Above this range, and upon marketing approval of the initial product contemplated by the Verily Collaboration Agreement , or upon commercialization of any other DexCom product that incorporates Verily intellectual property, we will pay to Verily a royalty percentage starting in the high single digits and declining to the mid-single digits based on our annual aggregate product sales. The Verily Collaboration Agreement shall be terminable by either party (a) upon uncured material breach of the Verily Collaboration Agreement by the other party, (b) if the second product contemplated by the Verily Collaboration Agreement has not been submitted to the FDA for approval by a specified date and (c) if the annual net sales for the products developed with Verily under the Verily Collaboration Agreement are less than a specified aggregate dollar amount. Additionally, we have the right to terminate the Verily Collaboration Agreement upon the expiration of the last to expire patent that covers a product developed under the Verily Collaboration Agreement . Edwards Lifesciences LLC On November 10, 2008, we entered into a Collaboration Agreement with Edwards Lifesciences LLC (“Edwards”) . The Collaboration Agreement was amended by the parties on May 5, 2009 (as amended, the “Collaboration Agreement”). In accordance with the Collaboration Agreement, the parties also entered into a Manufacturing and Supply Agreement and Quality Agreement, each dated as of November 10, 2008 (the “Manufacturing and Supply Agreement” and “Quality Agreement,” respectively). Pursuant to the Collaboration Agreement, the parties agreed to develop jointly and to market an in-hospital automatic blood glucose monitoring system ("In-Hospital Product"). On September 3, 2015, we and Edwards entered into a Restatement of License, Termination of Collaboration & Release Agreement (the “Restated Agreement”) terminating each of the Manufacturing and Supply Agreement and Quality Agreement, and amending in part the Collaboration Agreement. Pursuant to the Restated Agreement, we and Edwards agreed to a mutual release of claims, including any activities related to further development obligations or milestone payments. In addition, the Restated Agreement provides Edwards with a fully paid-up, royalty-free license to use certain of our intellectual property solely in the field of blood-based glucose monitoring within the hospital environment. Under the Restated Agreement, we reserve the right to market and sell our interstitial continuous glucose monitoring technology in all settings, including within the hospital market. No payments are required by either party in connection with the Restated Agreement. Tandem Diabetes Care, Inc. On February 1, 2012, we entered into a non-exclusive Development and Commercialization Agreement (the “Tandem Agreement”) with Tandem Diabetes Care, Inc. (“Tandem”) to integrate a future generation of our continuous glucose monitoring technology with Tandem ’s t:slim ™ insulin delivery system in the United States. On January 4, 2013, the Tandem Agreement was amended to allow for the integration of our G4 PLATINUM systems with Tandem 's t:slim insulin delivery system in the United States. We received an initial payment of $1.0 million as a result of the execution of the Tandem Agreement , which was fully recognized in development grant and other revenue as of December 31, 2014. During the year ended December 31, 2013 we recognized $0.5 million related to the initial consideration received. In July 2014, we received an additional $1.0 million milestone payment related to the regulatory submission by Tandem of their CGM enabled insulin pump. In September 2015, we received the final $1.0 million milestone payment related to the regulatory approval of Tandem 's CGM enabled insulin pump, which was recognized in development grant and other revenue for the twelve months ended December 31, 2015 . Under the terms of the Tandem Agreement , we are entitled to receive up to $1.0 million to offset certain development, clinical and regulatory expenses. Each of the milestones related to the Tandem Agreement is considered to be substantive. In September 2015, the Tandem Agreement was amended to eliminate Tandem’s obligation to pay DexCom a royalty of $100 for each Tandem t:slim G4 integrated pump system sold and instead to reallocate $100 for each Tandem t:slim G4 integrated pump system to incremental marketing activities for such pump systems, or marketing activities to support other jointly funded development projects. The Leona M. and Harry B Helmsley Charitable Trust In July 2013, we were awarded a $4.0 million grant (the "Helmsley Grant") from the Leona M. and Harry B. Helmsley Charitable Trust (the "Helmsley Trust") to accelerate the development of the sixth generation of our advanced glucose-sensing technologies (the " Gen 6 Sensor "). The funding is milestone-based and is contingent upon our meeting specific development milestones related to the development of the Gen 6 Sensor over a period of several years. Upon successful commercialization of our Gen 6 Sensor , we are obligated to either (1) make royalty payments based on a percentage of product sales of up to $2.0 million per year for four years, or (2) at our sole election, make a one-time $6.0 million royalty payment. The Helmsley Grant funds will offset research and development expense as incurred and earned. During the years ended 2015 , 2014 and 2013 , $1.0 million , $2.5 million and $0.5 million of the Helmsley Grant was received and earned.

Fair Value Measurements

Fair Value Measurements	12 Months Ended
	Dec. 31, 2015
Fair Value Disclosures [Abstract]
Fair Value Measurement	Fair Value Measurements We base the fair value of our Level 1 financial instruments that are in active markets using quoted market prices for identical instruments. We obtain the fair value of our Level 2 financial instruments, which are not in active markets, from a primary professional pricing source using quoted market prices for identical or comparable instruments, rather than direct observations of quoted prices in active markets. Fair value obtained from this professional pricing source can also be based on pricing models whereby all significant observable inputs, including maturity dates, issue dates, settlement date, benchmark yields, reported trades, broker-dealer quotes, issue spreads, benchmark securities, bids, offers or other market related data, are observable or can be derived from, or corroborated by, observable market data for substantially the full term of the asset. We validate the quoted market prices provided by our primary pricing service by comparing the fair values of our Level 2 marketable securities portfolio balance provided by our primary pricing service against the fair values of our Level 2 marketable securities portfolio balance provided by our investment managers. The following table represents our fair value hierarchy for our financial assets (cash equivalents and marketable securities) measured at fair value on a recurring basis as of December 31, 2015 (in millions): Fair Value Measurements Using Level 1 Level 2 Level 3 Total Cash equivalents $ — $ 32.1 $ — $ 32.1 Marketable securities, available for sale U.S. government agencies — 22.1 — 22.1 Corporate debt — 4.9 — 4.9 Commercial paper — 2.1 — 2.1 Total marketable securities, available for sale $ — $ 29.1 $ — $ 29.1 The following table represents our fair value hierarchy for our financial assets (cash equivalents, marketable securities and restricted cash) measured at fair value on a recurring basis as of December 31, 2014 (in millions): Fair Value Measurements Using Level 1 Level 2 Level 3 Total Cash equivalents $ — $ 54.3 $ — $ 54.3 Marketable securities, available for sale U.S. government agencies — 9.1 — 9.1 Corporate debt — 2.3 — 2.3 Commercial paper — 0.4 — 0.4 Total marketable securities, available for sale $ — $ 11.8 $ — $ 11.8 Restricted cash $ 1.0 $ — $ — $ 1.0 Our restricted cash balance as of December 31, 2014 included certificates of deposit. There were no transfers between Level 1 and Level 2 securities during the years ended December 31, 2015 and December 31, 2014 .

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2015
Income Taxes	7. Income Taxes We have recorded a net tax expense of $0.1 million for the years ended December 31, 2015 and 2014 , respectively, and a net tax benefit of $12,000 for the year ended December 31, 2013 . The tax expense for the years ended December 31, 2015 and 2014 were primarily related to foreign income taxes and state minimum taxes. At December 31, 2015 , we had federal and state tax net operating loss carryforwards of approximately $675.1 million and $424.3 million , respectively. The federal and state tax loss carryforwards will begin to expire in 2019 and 2016 , respectively, unless previously utilized. California net operating loss carryforwards of $39.6 million and $14.1 million will expire in 2016 and 2017, respectively. California net operating loss carryforwards of $321.8 million will expire from 2028 through 2035. Arizona net operating loss carryforwards of $0.7 million will expire in 2016. We also had federal and state research and development tax credit carryforwards of approximately $18.5 million and $20.5 million , respectively. The federal research and development tax credit will begin to expire in 2019 , unless previously utilized. The state research and development tax credit will carryforward indefinitely until utilized. Utilization of net operating losses and credit carryforwards are subject to an annual limitation due to ownership change limitations provided by Section 382 and 383 of the Internal Revenue Code of 1986, as amended, and similar state provisions. An ownership change limitation occurred as a result of the stock offering completed in February 2009. The limitation will likely result in approximately $2.1 million of U.S. income tax credits that will expire unused. The related deferred tax assets have been removed from the components of our deferred tax assets as summarized below. The tax benefits related to the remaining federal and state net operating losses and tax credit carryforwards may be further limited or lost if future cumulative changes in ownership exceed 50% within any three -year period. Significant components of our deferred tax assets as of December 31, 2015 and 2014 are shown below (in millions). A valuation allowance of approximately $196.4 million has been established as of December 31, 2015 to offset the deferred tax assets, as realization of such assets is uncertain. We maintain a deferred tax liability related to indefinite lived intangible assets that is not netted against deferred tax assets, as reversal of the taxable temporary difference cannot serve as a source of income for realization of the deferred tax assets, because the deferred tax liability will not reverse until the asset is sold or written down due to impairment. December 31, 2015 2014 Deferred tax assets: Net operating loss carryforwards $ 127.6 $ 132.2 Capitalized research and development expenses 17.0 5.0 Tax credits 19.1 9.0 Share-based compensation 20.8 15.5 Fixed and intangible assets (1.3 ) 1.2 Other, net 13.9 7.0 Total gross deferred tax assets 197.1 169.9 Less: valuation allowance (196.4 ) (169.0 ) Deferred tax liability related to acquired intangibles assets (0.8 ) (1.0 ) Net deferred tax liability $ (0.1 ) $ (0.1 ) We recognize windfall tax benefits associated with the exercise of share-based compensation directly to stockholders’ equity only when realized. Accordingly, deferred tax assets are not recognized for net operating loss carryforwards resulting from windfall tax benefits occurring from January 1, 2006 onward. At December 31, 2015 , deferred tax assets do not include $131.9 million of excess tax benefits from share-based compensation. As discussed in Note 1, we have elected to early adopt ASU 2015-17 prospectively beginning in the year ended December 31, 2015 with our deferred tax assets and deferred tax liabilities presented as noncurrent in the consolidated balance sheet for the year ended December 31, 2015. The reconciliation between our effective tax rate on income (loss) from continuing operations and the statutory rate is as follows: December 31, 2015 2014 2013 Income taxes at statutory rates 35.00 % 35.00 % 35.00 % State income tax, net of federal benefit 1.72 % (1.56 )% 2.70 % Permanent items (0.55 )% (0.80 )% (3.64 )% Research and development credits 17.40 % 7.50 % 6.17 % Stock and officers compensation (5.37 )% (15.93 )% (2.23 )% Rate change (0.30 )% (1.66 )% 7.11 % Other (0.36 )% (3.97 )% 0.08 % Change in valuation allowance (47.73 )% (19.24 )% (45.15 )% Income taxes at effective rates (0.19 )% (0.66 )% 0.04 % The following table summarizes the activity related to our gross unrecognized tax benefits (in millions): Balance at January 1, 2013 $ 4.8 Increases related to prior year tax positions 0.5 Increases related to current year tax positions 0.9 Balance at December 31, 2013 6.2 Increases related to current year tax positions 1.4 Balance at December 31, 2014 7.6 Increases related to prior year tax positions 2.6 Increases related to current year tax positions 5.4 Balance at December 31, 2015 $ 15.6 Due to the valuation allowance recorded against our deferred tax assets, none of the total unrecognized tax benefits as of December 31, 2015 would reduce our annual effective tax rate if recognized. Interest and penalties are classified as a component of income tax expense and were not material for all the periods presented. Due to net operating losses incurred, tax years from 1999 and forward remain open to examination by the major taxing jurisdictions to which we are subject. We do not expect any changes to our unrecognized tax benefits over the next twelve months. As of December 31, 2015 , U.S. income taxes have not been provided on approximately $0.5 million of accumulated undistributed earnings of our foreign subsidiary in Sweden, as we currently intend to indefinitely reinvest these earnings in our foreign operations. It is not practicable to estimate the amount of tax that might be payable if some or all of such earnings were to be remitted.

Employee Benefit Plans

Employee Benefit Plans	12 Months Ended
	Dec. 31, 2015
Employee Benefit Plans	. Employee Benefit Plans 401(k) Plan We have a defined contribution 401(k) retirement plan (the “401(k) Plan”) covering substantially all employees that meet certain age requirements. Employees may contribute up to 90% of their compensation per year (subject to a maximum limit by federal tax law). Under the 401(k) Plan, we may elect to match a discretionary percentage of contributions. No such matching contributions have been made to the 401(k) Plan since its inception. Employee Stock Purchase Plan In May 2015, we adopted a new ESPP, the 2015 Employee Stock Purchase Plan (the “2015 ESPP”) which replaced our 2005 ESPP and permits our eligible employees to purchase shares of common stock, at semi-annual intervals, through periodic payroll deductions. Payroll deductions may not exceed 10% of the participant’s cash compensation subject to certain limitations, and the purchase price will not be less than 85% of the lower of the fair market value of the stock at either the beginning of the applicable Offering Period or the Purchase Date. Under our 2015 ESPP, each Offering Period is twelve months, with new Offering Periods commencing every six months on the dates of March 1 and September 1 of each year. Each Offering Period consists of two (2) six month purchase periods (each a “Purchase Period”) during which payroll deductions of the participants are accumulated under the ESPP . The last business day of each Purchase Period is referred to as the “Purchase Date.” Purchase Dates are every six months on the dates of February 28 or February 29 and August 31. Under our 2005 ESPP, the Offering Periods commence on February 1 and August 1 of each year with Purchase dates on January 31 and July 31. During the years ended 2015 , 2014 and 2013 we issued 115,848 , 135,057 and 199,661 , respectively, shares of common stock under the 2005 ESPP . Equity Incentive Plans In May 2015, we adopted the 2015 Equity Incentive Plan (the “2015 Plan”) , which replaced the 2005 Equity Incentive Plan and provides for the grant of incentive and nonstatutory stock options, restricted stock, stock bonuses, stock appreciation rights, and restricted stock units to employees, directors or consultants of the Company. The total number of shares reserved for issuance pursuant to the 2015 Plan as of the date of adoption was 4.0 million and forfeited shares under the 2005 Equity Incentive Plan subsequent to May 28, 2015 are returned to the share reserve under the 2015 Plan and will be available for future awards. Stockholder approval is required to increase the maximum number of securities that may be issued under the 2015 Plan . Options generally vest over three or four years and expire ten years from the date of grant. In addition, incentive stock options may not be granted at a price less than the 100% of the fair market value on the date of grant. A summary of our stock option activity, and related information for the year ended December 31, 2015 is as follows (in millions except weighted-average exercise price and weighted-average remaining contractual term): Number of Shares Weighted- Average Exercise Price Weighted- Average Remaining Contractual Term (years) Aggregate Intrinsic Value Outstanding at December 31, 2014 3.1 $ 7.95 Exercised (1.8 ) 8.22 Forfeited — — Outstanding at December 31, 2015 1.3 $ 7.56 2.96 $ 94.5 Exercisable at December 31, 2015 1.3 $ 7.56 2.96 $ 94.5 The total intrinsic value of options exercised as of the date of exercise and total fair value of options vested was as follows (in millions): Years Ended December 31, 2015 2014 2013 Intrinsic value of options exercised $ 125.8 $ 99.0 $ 29.8 Fair value of options vested $ — $ 0.4 $ 1.3 We define in-the-money options at December 31, 2015 as options that had exercise prices that were lower than the $81.90 closing market price of our common stock at that date. The aggregate intrinsic value of options outstanding at December 31, 2015 is calculated as the difference between the exercise price of the underlying options and the market price of our common stock for the 1.3 million options that were in-the-money at that date. There were 1.3 million in-the-money options exercisable at December 31, 2015 . Valuation and expense information The following table summarizes share-based compensation expense related to employee stock options, restricted stock units and employee stock purchases for the years ended December 31, 2015 , 2014 and 2013 (in millions): Years Ended December 31, 2015 2014 2013 Cost of sales $ 8.1 $ 4.5 $ 2.6 Research and development 28.5 17.0 8.5 Selling, general and administrative 46.1 28.5 13.5 Share-based compensation expense included in operating expenses $ 82.7 $ 50.0 $ 24.6 At December 31, 2015 , unrecognized estimated compensation costs related to unvested restricted stock units totaled $151.8 million and are expected to be recognized through 2019 . We estimate the fair value of each option grant and ESPP purchase rights on the date of grant using the Black-Scholes option pricing model with the below assumptions. We did not have any option grants during the years ended 2015 , 2014 and 2013 . ESPP: Years Ended December 31, 2015 2014 2013 Risk free interest rate 0.15 – 0.25 0.10 – 0.12 0.13 – 0.17 Dividend yield — % — % — % Expected volatility of the Company’s stock 0.30 – 0.44 0.41 – 0.50 0.30 – 0.39 Expected life (in years) 1 1 1 Restricted Stock Units (RSUs) RSU awards typically vest annually over three or four years, and vesting is subject to continued employment. The RSUs had a weighted-average grant date fair value of $63.63 , $46.19 and $17.29 per share for the years ended December 31, 2015 , 2014 and 2013 , respectively. The total fair value of RSUs vested was $60.0 million , $27.0 million and $17.5 million for the years ended 2015 , 2014 and 2013 , respectively. The following table sets forth a summary of our RSU activity as of and for the year ended December 31, 2015 (in millions except weighted average grant date fair value): Shares Weighted Average Grant Date Fair Value Aggregate Intrinsic Value Nonvested at December 31, 2014 4.2 $ 33.35 Granted 2.1 63.63 Vested (2.0 ) 29.48 Forfeited (0.2 ) 32.62 Nonvested at December 31, 2015 4.1 $ 50.60 $ 339.0 Reserved Shares We have reserved shares of common stock for future issuance as follows (in millions) December 31, 2015 2014 Stock options and awards under our plans: Stock options granted and outstanding 1.3 3.1 Unvested restricted stock units 4.1 4.2 Reserved for future grant 3.7 0.3 Employee Stock Purchase Plan 1.5 2.5 Total 10.6 10.1

Quarterly Financial Information

Quarterly Financial Information	12 Months Ended
	Dec. 31, 2015
Quarterly Financial Information	. Quarterly Financial Information (Unaudited) The following is a summary of the quarterly results of operations for the years ended December 31, 2015 and 2014 (in millions except per share data): For the Three Months Ended December 31 September 30 June 30 March 31 Year ended December 31, 2015 Revenues $ 130.8 $ 105.2 $ 93.2 $ 72.8 Gross profit 91.2 74.7 66.0 46.5 Total operating expenses 89.6 117.1 69.6 59.2 Net income (loss) 1.5 (42.5 ) (3.7 ) (12.9 ) Basic net income (loss) per share (a) $ 0.02 $ (0.53 ) $ (0.05 ) $ (0.17 ) Diluted net income (loss) per share (a) $ 0.02 $ (0.53 ) $ (0.05 ) $ (0.17 ) Year ended December 31, 2014 Revenues $ 84.3 $ 69.0 $ 58.8 $ 47.1 Gross profit 59.4 47.2 39.9 29.8 Total operating expenses 57.8 52.2 45.7 42.1 Net income (loss) 1.3 (5.2 ) (6.0 ) (12.5 ) Basic net income (loss) per share (a) $ 0.02 $ (0.07 ) $ (0.08 ) $ (0.17 ) Diluted net income (loss) per share (a) $ 0.02 $ (0.08 ) $ (0.09 ) $ (0.17 ) (a) Basic and diluted earnings per share are computed independently for each of the quarters presented. Therefore, the sum of quarterly basic and diluted per share information may not equal annual basic and diluted earnings per share.

Valuation and Qualifying Accoun

Valuation and Qualifying Accounts	12 Months Ended
	Dec. 31, 2015
VALUATION AND QUALIFYING ACCOUNTS	SCHEDULE II—VALUATION AND QUALIFYING ACCOUNTS For the Years Ended December 31, 2015 , 2014 and 2013 (in millions) Allowance for doubtful accounts Balance December 31, 2012 $ 1.2 Provision for doubtful accounts 2.7 Write-off and adjustments (1.4 ) Recoveries 0.1 Balance December 31, 2013 $ 2.6 Allowance for doubtful accounts Balance December 31, 2013 $ 2.6 Provision for doubtful accounts 4.0 Write-off and adjustments (2.6 ) Recoveries 0.3 Balance December 31, 2014 $ 4.3 Allowance for doubtful accounts Balance December 31, 2014 $ 4.3 Provision for doubtful accounts 7.8 Write-off and adjustments (4.5 ) Recoveries 0.2 Balance December 31, 2015 $ 7.8

Subsequent Events (Notes)

Subsequent Events (Notes)	12 Months Ended
	Dec. 31, 2015
Subsequent Events [Abstract]
Subsequent Events	Subsequent Events On February 1, 2016, we entered into a Sublease (the “Sublease”) with Entropic Communications, LLC with respect to facilities in the building at 6350 Sequence Drive in San Diego, California (the “6350 Building”). Under the Sublease, we have leased approximately 132,600 square feet of space in the 6350 Building. The lease term extends through January 2022. Rent payable by us under the Sublease will be as follows (in millions): Fiscal Year Ending Total Annual Base Rent 2016 $ 0.8 2017 1.5 2018 2.2 2019 2.9 2020 3.4 Thereafter 3.8 Total $ 14.6 In addition, under the Sublease, we are obligated to pay a share of the real estate taxes and operating costs for the 6350 Building and were required to provide a security deposit of $0.3 million . The total obligation for rent under the life of the lease is $14.6 million , excluding real estate taxes and operating costs.

Organization and Summary of S19

Organization and Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2015
Disclosure Organization And Summary Of Significant Accounting Policies Additional Information [Abstract]
Organization and Business	Organization and Business DexCom, Inc. is a medical device company focused on the design, development and commercialization of continuous glucose monitoring (“CGM”) systems for ambulatory use by people with diabetes and by healthcare providers in the hospital for the treatment of people with and without diabetes. Unless the context requires otherwise, the terms “we,” “us,” “our,” the “company,” or “DexCom” refer to DexCom, Inc. and its subsidiaries.
Basis of Presentation	Basis of Presentation We have incurred operating losses since our inception and have an accumulated deficit of $555.4 million at December 31, 2015 . As of December 31, 2015 , we had available cash, cash equivalents and short-term marketable securities totaling $115.2 million and working capital of $164.4 million . Our ability to transition to, and maintain, profitable operations is dependent upon achieving a level of revenues adequate to support our cost structure. If events or circumstances occur such that we do not meet our operating plan as expected, we may be required to reduce planned increases in compensation expenses and other operating expenses needed to support the growth of our business which could have an adverse impact on our ability to achieve our intended business objectives. We believe our working capital resources will be sufficient to fund our operations through at least December 31, 2016 .
Principles of Consolidation	Principles of Consolidation The consolidated financial statements include the accounts of DexCom and our wholly owned subsidiaries, DexCom AB, and SweetSpot Diabetes Care, Inc. (“SweetSpot”). All significant intercompany balances and transactions have been eliminated in consolidation.
Segment Reporting	Segment Reporting and Geographic Information An operating segment is identified as a component of a business that has discrete financial information available, and one for which the chief operating decision maker must decide the level of resource allocation. In addition, the guidance for segment reporting indicates certain quantitative thresholds. The operations of SweetSpot, our subsidiary, does not meet the definition of an operating segment and are currently not material, but may become material in the future. We currently consider our operations to be, and manage our business globally within, one reportable segment, which is consistent with how our President and Chief Executive Officer, who is our chief operating decision maker, reviews our business, makes investment and resource allocation decisions and assesses operating performance. We sell our products through a direct sales force in the United States and through distribution arrangements in the United States, Canada, Australia, New Zealand, and in portions of Europe, Asia, the Middle East, Latin America, and Africa. DexCom, Inc. is domiciled in the United States. During the years ended 2015 , 2014 and 2013 , no individual country, outside of our country of domicile, generated revenue that represented more than 10% of our total revenue. Product revenue is designated based on the geographic location to which we deliver the product. Development grant and other revenue is attributed to countries based upon the location of the headquarters of our customer or their billing address. During fiscal 2015 and 2014 , total revenues attributable to the United States and outside of the United States were as follows: Years Ended December 31, 2015 2014 Amount % Amount % (In millions, except percentages) Revenues: United States $ 347.4 86 % $ 224.2 86 % Outside of the United States 54.6 14 % 35.0 14 % Total $ 402.0 100 % $ 259.2 100 % Revenue attributed to countries outside of the United States for fiscal 2013 did not exceed 10% of our total revenue. Substantially all of our long-lived assets are located in the United States.
Use of Estimates	Use of Estimates The preparation of consolidated financial statements in conformity with U.S. GAAP requires us to make estimates and assumptions that affect the amounts reported in the consolidated financial statements and accompanying notes. Actual results could differ from these estimates. Significant estimates include excess or obsolete inventories, valuation of inventory, warranty accruals, allowance for bad debt, refunds and rebates, including pharmacy rebates and share­based compensation expense.
Cash and Cash Equivalents	Cash and Cash Equivalents We invest our excess cash in bank deposits, money market accounts, and debt securities. We consider all highly liquid investments with a maturity of 90 days or less at the time of purchase to be cash equivalents.
Accounts Receivables	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. Uncollectible accounts are written-off against the allowance after appropriate collection efforts have been exhausted and when it is deemed that a customer account is uncollectible. Generally, receivable balances greater than one year past due are deemed uncollectible.
Letters Of Credit	Letters of Credit At December 31, 2015 and 2014 , we had irrevocable letters of credit outstanding with a commercial bank for approximately $0.7 million and $0.7 million , respectively, securing our facility leases. The letters of credit are secured by cash equivalents. The letter of credit as of December 31, 2014 was also secured by an equal amount of restricted cash which has been separately disclosed in the accompanying consolidated balance sheets.
Concentration of Credit Risk	Concentration of Credit Risk Financial instruments which potentially subject us to concentrations of credit risk consist primarily of cash, cash equivalents, short-term investment securities, and accounts receivable. We limit our exposure to credit loss by placing our cash with high credit quality financial institutions. We have established guidelines relative to diversification of our cash and investment securities and their maturities that are intended to secure safety and liquidity. These guidelines are periodically reviewed and modified to take advantage of trends in yields and interest rates and changes in our operations and financial position. The following table summarizes customers who accounted for 10% or more of net accounts receivable: December 31, 2015 2014 Customer A 23% 23% Customer B 13% 12%
Impairment of Long-Lived Assets	Impairment of Long-Lived Assets We record impairment losses on long-lived assets used in operations when events and circumstances indicate that assets might be impaired and the undiscounted cash flows estimated to be generated by those assets are less than the carrying amount of those assets. We have not experienced any material impairment losses on assets used in operations.
Share-Based Compensation	Share-Based Compensation Share-based compensation expense is measured at the grant date based on the estimated fair value of the award and is recognized, for awards that are ultimately expected to vest, primarily on a straight-line basis over the requisite service period of the individual grants, which typically equals the vesting period. The fair value of our RSUs is based on the market price of our common stock on the date of grant. We are also required to estimate at grant the likelihood that the award will ultimately vest (the “pre-vesting forfeiture rate”), and to revise the estimate, if necessary, in future periods if the actual forfeiture rate differs. We determine the pre-vesting forfeiture rate of an award based on our historical pre-vesting award forfeiture experience, giving consideration to company-specific events impacting historical pre-vesting award forfeiture experience that are unlikely to occur in the future as well as anticipated future events that may impact forfeiture rates. We use our historical data to estimate pre-vesting forfeitures and record stock-based compensation expense only for those awards that are expected to vest.
Revenue Recognition	Revenue Recognition We sell our durable systems and disposable units through a direct sales force in the United States and through distribution arrangements in the United States , Canada , Australia , New Zealand , and in portions of Europe , Asia , the Middle East , Latin America and Africa . Components are individually priced and can be purchased separately or together. We receive payment directly from customers who use our products, as well as from distributors, organizations and third-party payors. Our durable system includes a reusable transmitter, a receiver, a power cord and a USB cable. Disposable sensors for use with the durable system are sold separately in packages of four. We provide free of charge software and mobile applications for use with our durable systems and disposable sensors. The initial durable system price is generally not dependent upon the purchase of any amount of disposable sensors. Revenue is recognized when persuasive evidence of an arrangement exists, delivery has occurred or services have been rendered, the price is fixed or determinable, and collectability is reasonably assured. Revenue on product sales is generally recognized upon shipment, which is when title and the risk of loss have been transferred to the customer and there are no other post shipment obligations. With respect to customers who directly pay for products, the products are generally paid for at the time of shipment using a customer’s credit card and do not include customer acceptance provisions. We recognize revenue from contracted insurance payors based on the contracted rate. For non-contracted insurance payors, we obtain prior authorization from the payor and recognize revenue based on the estimated collectible amount and historical experience. We also receive a prescription or statement of medical necessity and, for insurance reimbursement customers, an assignment of benefits prior to shipment. We provide a “ 30 -day money back guarantee” program whereby customers who purchase a durable system and a package of four disposable sensors may return the durable system for any reason within thirty days of purchase and receive a full refund of the purchase price of the durable system. We accrue for estimated returns, refunds and rebates, including pharmacy rebates, by reducing revenues and establishing a liability account at the time of shipment based on historical experience. Returns have historically been immaterial. Allowances for rebates include contracted discounts with commercial payors and are amounts owed after the final dispensing of the product by a distributor or retail pharmacy to a pharmacy benefit plan participant and are based upon contractual agreements with private sector benefit providers. The allowance for rebates is based on contractual discount rates, expected utilization under each contract and our estimate of the amount of inventory in the distribution channel that will become subject to such rebates. Our estimates for expected utilization for rebates are based on historical rebate claims and to a lesser extent third party market research data. Rebates are generally invoiced and paid monthly or quarterly in arrears so that our accrual consists of an estimate of the amount expected to be incurred for the current month's or quarter’s activity, plus an accrual for unpaid rebates from prior periods, and an accrual for inventory in the distribution channel. We have entered into distribution agreements with Byram , Edgepark and other distributors that allow the distributors to sell our durable systems and disposable units. We have contracts with certain distributors who stock our products, and we refer to these distributors as Stocking Distributors , whereby the Stocking Distributors fulfill orders for our product from their inventory. We also have contracts with certain distributors that do not stock our products, but rather products are shipped directly to the customer by us on behalf of our distributor, and we refer to these distributors as Drop-Ship Distributors. Revenue is recognized based on contracted prices and invoices are either paid by check following the issuance of a purchase order or letter of credit, or they are paid by wire at the time of placing the order. Terms of distributor orders are generally FOB (or Free Carrier (“ FCA ”) shipping point for international orders). Distributors do not have rights of return per their distribution agreement outside of our standard warranty. The distributors typically have a limited time frame to notify us of any missing, damaged, defective or non-conforming products. For any such products, we shall either, at our option, replace the portion of defective or non-conforming product at no additional cost to the distributor or cancel the order and refund any portion of the price paid to us at that time for the sale in question. One of our distributors, Byram , accounted for $74.1 million , $46.1 million and $24.3 million in gross revenue, which represents 18% , 18% and 15% of our total revenues for the twelve months ended December 31, 2015 , 2014 and 2013 , respectively. Another one of our distributors, Edgepark , accounted for $42.6 million , $28.1 million and $23.1 million in gross revenue, which represents 11% , 11% and 14% of our total revenues for the twelve months ended December 31, 2015 , 2014 and 2013 , respectively.
Warranty Accrual	Warranty Accrual Estimated warranty costs associated with a product are recorded at the time of shipment. We estimate future warranty costs by analyzing historical warranty experience for the timing and amount of returned product, and these estimates are evaluated on at least a quarterly basis to determine the continued appropriateness of such assumptions.
Research and Development	Research and Development All costs of research and development are expensed as incurred. Research and development expenses primarily include salaries, bonus and payroll related costs, clinical trials, regulatory expenses, quality assurance programs, part components, share-based compensation, and fees paid to consultants.
Foreign Currency	Foreign Currency The financial statements of our subsidiary in Sweden, whose functional currency is the Swedish Krona, are translated into U.S. dollars for financial reporting purposes. Assets and liabilities are translated at period-end exchange rates, and revenue and expense transactions are translated at average exchange rates for the period. Cumulative translation adjustments are recognized as part of comprehensive income and are included in accumulated other comprehensive loss in the consolidated balance sheet. Gains and losses on transactions denominated in other than the functional currency are reflected in operations. To date the results of operations of this subsidiary and related translation adjustments have not been material in our consolidated results.
Comprehensive Loss	Comprehensive Loss We report all components of comprehensive loss, including net loss, in the consolidated 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. Net loss and comprehensive loss, including unrealized gains and losses on marketable securities and foreign currency translation adjustments, are reported, net of their related tax effect, to arrive at comprehensive loss.
Inventory	Inventory Inventory is valued at the lower of cost or market value on a part-by-part basis that approximates first in, first out. We make adjustments to reduce the cost of inventory to its net realizable value, if required, for estimated excess, obsolete and potential scrapped inventories. Factors influencing these adjustments include inventories on hand and on order compared to estimated future usage and sales for existing and new products, as well as judgments regarding quality control testing data, and assumptions about the likelihood of scrap and obsolescence. Once written down the adjustments are considered permanent and are not reversed until the related inventory is sold or disposed. Our products require customized products and components that currently are available from a limited number of sources. We purchase certain components and materials from single sources due to quality considerations, costs or constraints resulting from regulatory requirements.
Deferred Rent	Deferred Rent Rent expense is recorded on a straight-line basis over the term of the lease. The difference between rent expense accrued and amounts paid under the lease agreement is recorded as deferred rent in the accompanying consolidated balance sheets.
Income Taxes	Income Taxes We account for income taxes under the asset and liability method, which requires the recognition of deferred tax assets and liabilities for the expected future tax consequences of events that have been included in the financial statements. Under this method, we determine deferred tax assets and liabilities on the basis of the differences between the financial statement and tax bases of assets and liabilities by using enacted tax rates in effect for the year in which the differences are expected to reverse. The effect of a change in tax rates on deferred tax assets and liabilities is recognized in income in the period that includes the enactment date. We recognize deferred tax assets to the extent that we believe that these assets are more likely than not to be realized, which requires significant judgment. We establish a valuation allowance against our net deferred tax assets to reduce them to the amount expected to be realized. The realization of deferred tax assets is dependent, in part, upon future taxable income. In assessing whether our deferred tax assets will be realized, we consider all available evidence, both positive and negative. Such evidence includes historical earnings, future reversals of existing taxable temporary differences, estimates of future taxable income, and the feasibility of ongoing tax planning strategies. We record uncertain tax positions in accordance with ASC 740 on the basis of a two-step process in which (1) we determine whether it is more likely than not that the tax positions will be sustained on the basis of the technical merits of the position and (2) for those tax positions that meet the more-likely-than-not recognition threshold, we recognize the largest amount of tax benefit that is more than 50 percent likely to be realized upon ultimate settlement with the related tax authority. We file income tax returns in the United States, Sweden and in various state jurisdictions with varying statutes of limitations. Due to net operating losses incurred, our income tax returns from inception to date are subject to examination by taxing authorities. Our policy is to recognize interest expense and penalties related to income tax matters as a component of income tax expense. As of December 31, 2015 , we had no interest or penalties accrued for uncertain tax positions.
Marketable Securities	Marketable Securities We have classified our marketable securities with remaining maturity at purchase of more than three months and remaining maturities of one year or less as short-term available-for-sale marketable securities. Marketable securities with remaining maturities of greater than one year are also classified as short-term available-for-sale marketable securities as such marketable securities represent the investment of cash that is available for current operations. We carry our marketable securities at fair value with unrealized gains and losses, if any, reported as a separate component of stockholders' equity and included in comprehensive loss. Realized gains and losses are calculated using the specific identification method and recorded as interest income. We invest in various types of securities, including debt securities in government-sponsored entities, corporate debt securities, U.S. Treasury securities and commercial paper. We do not generally intend to sell the investments and it is not more likely than not that we will be required to sell the investments before recovery of their amortized cost bases, which may be at maturity.
Fair Value Measurements	Fair Value Measurements The fair value hierarchy described by the authoritative guidance for fair value measurements is based on three levels of inputs, of which the first two are considered observable and the last unobservable, that may be used to measure fair value and include the following: Level 1—Quoted prices in active markets for identical assets or liabilities. Level 2—Inputs other than Level 1 that are observable, either directly or indirectly, such as quoted prices for similar assets or liabilities; quoted prices in markets that are not active; or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities. Level 3—Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets or liabilities. We carry our marketable securities at fair value. The carrying amounts of financial instruments, such as cash and cash equivalents, accounts receivable, prepaid expenses and other current assets, accounts payable and accrued liabilities, are carried at cost, which approximate the related fair values due to the short-term maturities of these instruments. For additional detail see Note 6 “Fair Value Measurements.”
Property and Equipment	Property and Equipment Property and equipment is stated at cost and depreciated over the estimated useful lives of the assets, generally three years for computer equipment, four years for machinery and equipment, and five years for furniture and fixtures, using the straight-line method. Leasehold improvements are stated at cost and amortized over the shorter of the estimated useful lives of the assets or the remaining lease term.
Goodwill and Intangible Assets	Goodwill and Intangible Assets Goodwill, which has an indefinite useful life, represents the excess of cost over fair value of net assets acquired. The change in the carrying value of goodwill during the twelve months ended December 31, 2015 resulted from an acquisition of a small privately held engineering consulting company with 10 full time employees to complement our research and development activities, which closed in April 2015. Our identifiable intangible assets are comprised of acquired technologies, customer relationships, covenants not-to-compete, in-process research and development and trade names. The cost of identifiable intangible assets with finite lives is generally amortized on a straight-line basis over the assets’ respective estimated useful lives. We test goodwill and intangible assets with indefinite lives for impairment on an annual basis. Also, between annual tests we test for impairment if events and circumstances indicate it is more likely than not that the fair value is less than the carrying value. Events that would indicate impairment and trigger an interim impairment assessment include, but are not limited to, current economic and market conditions, including a decline in market capitalization, a significant adverse change in legal factors, business climate or operational performance of the business and an adverse action or assessment by a regulator.
Recent Accounting Guidance	Recent Accounting Guidance In May 2014, the Financial Accounting Standards Board ("FASB") issued authoritative guidance for Revenue from Contracts with Customers, to supersede nearly all existing revenue recognition guidance under U.S. GAAP. The core principle of the guidance is to recognize revenues when promised goods or services are transferred to customers in an amount that reflects the consideration that is expected to be received for those goods or services. The guidance defines a five step process to achieve this core principle and it is possible when the five step process is applied, more judgment and estimates may be required within the revenue recognition process than required under existing U.S. GAAP including 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 updated standard permits the use of either the retrospective or cumulative effect transition method and is effective for us in our first quarter of fiscal 2018. Early adoption is not permitted. We have not yet selected a transition method and we are currently evaluating the effect that the updated standard will have on our consolidated financial statements and related disclosures. In July 2015, the FASB issued guidance to change the subsequent measurement of inventory from lower of cost or market to lower of cost and net realizable value. The guidance requires that inventory accounted for under the first-in, first-out (FIFO) or average cost methods be measured at the lower of cost and net realizable value, where net realizable value represents the estimated selling price of inventory in the ordinary course of business, less reasonably predictable costs of completion, disposal, and transportation. The guidance is effective for us beginning in the first quarter of fiscal 2018. Earlier application is permitted as of the beginning of an interim or annual reporting period. We are currently evaluating the effect this guidance will have on our consolidated financial statements. In November 2015, the FASB issued ASU 2015-17, Balance Sheet Classification of Deferred Taxes ("ASU 2015-17"), which requires entities to present deferred tax assets and deferred tax liabilities as noncurrent in a classified balance sheet. The ASU simplifies the current guidance in ASC Topic 740, Income Taxes, which requires entities to separately present deferred tax assets and liabilities as current and noncurrent in a classified balance sheet. The current requirement that deferred tax liabilities and assets of a tax-paying component of an entity be offset and presented as a single amount is not affected by the amendments in this ASU. ASU 2015-17 is effective for fiscal years beginning after December 15, 2016, and interim periods within those annual periods, with early adoption permitted. We have elected to early adopt prospectively beginning in the year ended December 31, 2015 with our deferred tax assets and deferred tax liabilities presented as noncurrent in the consolidated balance sheet and related disclosures for the year ended December 31, 2015.

Organization and Summary of S20

Organization and Summary of Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2015
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Schedule of Revenue from External Customers and Long-Lived Assets, by Geographical Areas [Table Text Block]	During fiscal 2015 and 2014 , total revenues attributable to the United States and outside of the United States were as follows: Years Ended December 31, 2015 2014 Amount % Amount % (In millions, except percentages) Revenues: United States $ 347.4 86 % $ 224.2 86 % Outside of the United States 54.6 14 % 35.0 14 % Total $ 402.0 100 % $ 259.2 100 %
Schedules of Concentration of Risk, by Risk Factor [Table Text Block]	The following table summarizes customers who accounted for 10% or more of net accounts receivable: December 31, 2015 2014 Customer A 23% 23% Customer B 13% 12%

Net Loss Per Common Share (Tabl

Net Loss Per Common Share (Tables)	12 Months Ended
	Dec. 31, 2015
Earnings Per Share [Abstract]
Historical Outstanding Anti-Dilutive Securities	Historical outstanding anti-dilutive securities not included in diluted net loss per share attributable to common stockholders calculation (in millions): Years Ended December 31, 2015 2014 2013 Options outstanding to purchase common stock 1.3 3.1 5.8 Unvested restricted stock units 4.1 4.2 3.6 Total 5.4 7.3 9.4

Financial Statement Details (Ta

Financial Statement Details (Tables)	12 Months Ended
	Dec. 31, 2015
Disclosure of Financial Statement Details [Abstract]
Short Term Marketable Securities, Available for Sale	Short term marketable securities, consisting solely of debt securities were as follows: December 31, 2015 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Estimated Market Value U.S. government agencies $ 22.1 $ — $ — $ 22.1 Corporate debt 4.9 — — 4.9 Commercial paper 2.1 — — 2.1 Total $ 29.1 $ — $ — $ 29.1 December 31, 2014 Amortized Cost Gross Unrealized Gains Gross Unrealized Losses Estimated Market Value U.S. government agencies $ 9.1 $ — $ — $ 9.1 Corporate debt 2.3 — — 2.3 Commercial paper 0.4 — — 0.4 Total $ 11.8 $ — $ — $ 11.8
Accounts Receivable	Accounts Receivable December 31, 2015 2014 Accounts receivable $ 82.0 $ 46.8 Less allowance for doubtful accounts, sales returns and discounts (7.9 ) (4.4 ) Total $ 74.1 $ 42.4
Inventory	Inventory December 31, 2015 2014 Raw materials $ 16.0 $ 7.6 Work-in-process 2.6 1.0 Finished goods 16.6 7.4 Total $ 35.2 $ 16.0
Property and Equipment	Property and Equipment December 31, 2015 2014 Furniture and fixtures $ 3.7 $ 3.9 Computer equipment 21.0 18.9 Machinery and equipment 47.2 26.5 Leasehold improvements 21.0 14.7 Total 92.9 64.0 Accumulated depreciation and amortization (38.2 ) (32.8 ) Property and equipment, net $ 54.7 $ 31.2
Schedule of Intangible Assets and Goodwill	Goodwill and Intangible Assets Goodwill and intangible assets as of December 31, 2015 consisted of the following (in millions, except months): Weighted-Average Amortization Period (in months) Gross Amount Accumulated Amortization Intangible Assets, net Intangible assets subject to amortization Developed technology 109 $ 3.2 $ (1.5 ) $ 1.7 Customer-related intangible 70 0.6 (0.4 ) 0.2 Covenants not-to-compete 70 0.2 (0.1 ) 0.1 In-process research and development 51 0.2 (0.1 ) 0.1 Total $ 4.2 $ (2.1 ) $ 2.1 Intangible assets not subject to amortization Trademarks and trade names 0.1 Goodwill 3.7 Total $ 3.8 Goodwill and intangible assets as of December 31, 2014 consisted of the following (in millions, except months): Weighted-Average Amortization Period (in months) Gross Amount Accumulated Amortization Intangible Assets, net Intangible assets subject to amortization Developed technology 109 $ 3.2 $ (1.2 ) $ 2.0 Customer-related intangible 70 0.6 (0.3 ) 0.3 Covenants not-to-compete 70 0.2 (0.1 ) 0.1 Total $ 4.0 $ (1.6 ) $ 2.4 Intangible assets not subject to amortization In-process research and development 0.2 Trademarks and trade names 0.1 Goodwill 3.2 Total $ 3.5
Schedule of Estimated Future Amortization Expense	The following table sets forth the total future amortization expense related to intangible assets subject to amortization as of December 31, 2015 : Fiscal Year Ending 2016 $ 0.5 2017 0.5 2018 0.3 2019 0.3 2020 0.3 Thereafter through 2021 0.2 Total $ 2.1
Accounts Payable and Accrued Liabilities	Accounts Payable and Accrued Liabilities December 31, 2015 2014 Accounts payable trade $ 19.0 $ 9.9 Accrued tax, audit, and legal fees 2.1 1.6 Clinical trials 0.7 0.4 Accrued other including warranty 17.1 8.5 Total $ 38.9 $ 20.4
Accrued Payroll And Related Expenses	Accrued Payroll and Related Expenses December 31, 2015 2014 Accrued paid time off $ 4.4 $ 3.2 Accrued wages, bonus and taxes 18.4 12.5 Other accrued employee benefits 2.1 1.5 Total $ 24.9 $ 17.2
Accrued Warranty	Accrued Warranty Warranty costs are reflected in the consolidated statements of operations as product cost of sales. A reconciliation of our accrued warranty costs for the twelve months ended December 31, 2015 and 2014 were as follows: Years Ended December 31, 2015 2014 Beginning balance $ 1.3 $ 0.9 Charges to costs and expenses 9.0 5.2 Costs incurred (7.0 ) (4.8 ) Ending balance $ 3.3 $ 1.3

Commitments and Contingencies (

Commitments and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2015
Commitments and Contingencies Disclosure [Abstract]
Rental Obligations	Rental obligations, excluding real estate taxes, operating costs, and tenant improvement allowances, under all lease agreements as of December 31, 2015 were as follows (in millions): Fiscal Year Ending 2016 $ 4.8 2017 4.4 2018 5.2 2019 5.3 2020 5.3 Thereafter 6.5 Total $ 31.5 Rent payable by us under the Sublease will be as follows (in millions): Fiscal Year Ending Total Annual Base Rent 2016 $ 0.8 2017 1.5 2018 2.2 2019 2.9 2020 3.4 Thereafter 3.8 Total $ 14.6

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	12 Months Ended
	Dec. 31, 2015
Fair Value Disclosures [Abstract]
Fair Value Hierarchy for Financial Assets	The following table represents our fair value hierarchy for our financial assets (cash equivalents and marketable securities) measured at fair value on a recurring basis as of December 31, 2015 (in millions): Fair Value Measurements Using Level 1 Level 2 Level 3 Total Cash equivalents $ — $ 32.1 $ — $ 32.1 Marketable securities, available for sale U.S. government agencies — 22.1 — 22.1 Corporate debt — 4.9 — 4.9 Commercial paper — 2.1 — 2.1 Total marketable securities, available for sale $ — $ 29.1 $ — $ 29.1 The following table represents our fair value hierarchy for our financial assets (cash equivalents, marketable securities and restricted cash) measured at fair value on a recurring basis as of December 31, 2014 (in millions): Fair Value Measurements Using Level 1 Level 2 Level 3 Total Cash equivalents $ — $ 54.3 $ — $ 54.3 Marketable securities, available for sale U.S. government agencies — 9.1 — 9.1 Corporate debt — 2.3 — 2.3 Commercial paper — 0.4 — 0.4 Total marketable securities, available for sale $ — $ 11.8 $ — $ 11.8 Restricted cash $ 1.0 $ — $ — $ 1.0

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2015
Deferred Tax Assets and Liabilities	December 31, 2015 2014 Deferred tax assets: Net operating loss carryforwards $ 127.6 $ 132.2 Capitalized research and development expenses 17.0 5.0 Tax credits 19.1 9.0 Share-based compensation 20.8 15.5 Fixed and intangible assets (1.3 ) 1.2 Other, net 13.9 7.0 Total gross deferred tax assets 197.1 169.9 Less: valuation allowance (196.4 ) (169.0 ) Deferred tax liability related to acquired intangibles assets (0.8 ) (1.0 ) Net deferred tax liability $ (0.1 ) $ (0.1 )
Reconciliation Between Effective Tax Rate and Statutory Rate	The reconciliation between our effective tax rate on income (loss) from continuing operations and the statutory rate is as follows: December 31, 2015 2014 2013 Income taxes at statutory rates 35.00 % 35.00 % 35.00 % State income tax, net of federal benefit 1.72 % (1.56 )% 2.70 % Permanent items (0.55 )% (0.80 )% (3.64 )% Research and development credits 17.40 % 7.50 % 6.17 % Stock and officers compensation (5.37 )% (15.93 )% (2.23 )% Rate change (0.30 )% (1.66 )% 7.11 % Other (0.36 )% (3.97 )% 0.08 % Change in valuation allowance (47.73 )% (19.24 )% (45.15 )% Income taxes at effective rates (0.19 )% (0.66 )% 0.04 %
Summary of Unrecognized Tax Benefits	The following table summarizes the activity related to our gross unrecognized tax benefits (in millions): Balance at January 1, 2013 $ 4.8 Increases related to prior year tax positions 0.5 Increases related to current year tax positions 0.9 Balance at December 31, 2013 6.2 Increases related to current year tax positions 1.4 Balance at December 31, 2014 7.6 Increases related to prior year tax positions 2.6 Increases related to current year tax positions 5.4 Balance at December 31, 2015 $ 15.6

Employee Benefit Plans (Tables)

Employee Benefit Plans (Tables)	12 Months Ended
	Dec. 31, 2015
Summary of Stock Option Activity	A summary of our stock option activity, and related information for the year ended December 31, 2015 is as follows (in millions except weighted-average exercise price and weighted-average remaining contractual term): Number of Shares Weighted- Average Exercise Price Weighted- Average Remaining Contractual Term (years) Aggregate Intrinsic Value Outstanding at December 31, 2014 3.1 $ 7.95 Exercised (1.8 ) 8.22 Forfeited — — Outstanding at December 31, 2015 1.3 $ 7.56 2.96 $ 94.5 Exercisable at December 31, 2015 1.3 $ 7.56 2.96 $ 94.5
Schedule of Intrinsic Value of Options Exercised and Fair Value of Options Vested	The total intrinsic value of options exercised as of the date of exercise and total fair value of options vested was as follows (in millions): Years Ended December 31, 2015 2014 2013 Intrinsic value of options exercised $ 125.8 $ 99.0 $ 29.8 Fair value of options vested $ — $ 0.4 $ 1.3
Schedule of Share-Based Compensation Expenses	The following table summarizes share-based compensation expense related to employee stock options, restricted stock units and employee stock purchases for the years ended December 31, 2015 , 2014 and 2013 (in millions): Years Ended December 31, 2015 2014 2013 Cost of sales $ 8.1 $ 4.5 $ 2.6 Research and development 28.5 17.0 8.5 Selling, general and administrative 46.1 28.5 13.5 Share-based compensation expense included in operating expenses $ 82.7 $ 50.0 $ 24.6
Schedule of Valuation Assumptions for Employee Stock Purchase Plan	ESPP: Years Ended December 31, 2015 2014 2013 Risk free interest rate 0.15 – 0.25 0.10 – 0.12 0.13 – 0.17 Dividend yield — % — % — % Expected volatility of the Company’s stock 0.30 – 0.44 0.41 – 0.50 0.30 – 0.39 Expected life (in years) 1 1 1
Schedule of Restricted Stock Units Activity	The following table sets forth a summary of our RSU activity as of and for the year ended December 31, 2015 (in millions except weighted average grant date fair value): Shares Weighted Average Grant Date Fair Value Aggregate Intrinsic Value Nonvested at December 31, 2014 4.2 $ 33.35 Granted 2.1 63.63 Vested (2.0 ) 29.48 Forfeited (0.2 ) 32.62 Nonvested at December 31, 2015 4.1 $ 50.60 $ 339.0
Schedule of Stock Options Reserved for Future Issuance	Reserved Shares We have reserved shares of common stock for future issuance as follows (in millions) December 31, 2015 2014 Stock options and awards under our plans: Stock options granted and outstanding 1.3 3.1 Unvested restricted stock units 4.1 4.2 Reserved for future grant 3.7 0.3 Employee Stock Purchase Plan 1.5 2.5 Total 10.6 10.1

Quarterly Financial Informati27

Quarterly Financial Information (Tables)	12 Months Ended
	Dec. 31, 2015
Schedule of Quarterly Financial Information	The following is a summary of the quarterly results of operations for the years ended December 31, 2015 and 2014 (in millions except per share data): For the Three Months Ended December 31 September 30 June 30 March 31 Year ended December 31, 2015 Revenues $ 130.8 $ 105.2 $ 93.2 $ 72.8 Gross profit 91.2 74.7 66.0 46.5 Total operating expenses 89.6 117.1 69.6 59.2 Net income (loss) 1.5 (42.5 ) (3.7 ) (12.9 ) Basic net income (loss) per share (a) $ 0.02 $ (0.53 ) $ (0.05 ) $ (0.17 ) Diluted net income (loss) per share (a) $ 0.02 $ (0.53 ) $ (0.05 ) $ (0.17 ) Year ended December 31, 2014 Revenues $ 84.3 $ 69.0 $ 58.8 $ 47.1 Gross profit 59.4 47.2 39.9 29.8 Total operating expenses 57.8 52.2 45.7 42.1 Net income (loss) 1.3 (5.2 ) (6.0 ) (12.5 ) Basic net income (loss) per share (a) $ 0.02 $ (0.07 ) $ (0.08 ) $ (0.17 ) Diluted net income (loss) per share (a) $ 0.02 $ (0.08 ) $ (0.09 ) $ (0.17 )

Subsequent Events Subsequent Ev

Subsequent Events Subsequent Events (Tables)	12 Months Ended
	Dec. 31, 2015
Subsequent Events [Abstract]
Schedule of Future Minimum Rental Payments for Operating Leases [Table Text Block]	Rental obligations, excluding real estate taxes, operating costs, and tenant improvement allowances, under all lease agreements as of December 31, 2015 were as follows (in millions): Fiscal Year Ending 2016 $ 4.8 2017 4.4 2018 5.2 2019 5.3 2020 5.3 Thereafter 6.5 Total $ 31.5 Rent payable by us under the Sublease will be as follows (in millions): Fiscal Year Ending Total Annual Base Rent 2016 $ 0.8 2017 1.5 2018 2.2 2019 2.9 2020 3.4 Thereafter 3.8 Total $ 14.6

Organization and Summary of S29

Organization and Summary of Significant Accounting Policies - Additional Information (Detail) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2015USD ($)	Sep. 30, 2015USD ($)	Jun. 30, 2015USD ($)	Mar. 31, 2015USD ($)	Dec. 31, 2014USD ($)	Sep. 30, 2014USD ($)	Jun. 30, 2014USD ($)	Mar. 31, 2014USD ($)	Dec. 31, 2015USD ($)	Dec. 31, 2014USD ($)	Dec. 31, 2013USD ($)
Organization And Summary Of Significant Accounting Policies [Line Items]
Accumulated deficit	$ 555.4				$ 497.8				$ 555.4	$ 497.8
Cash, cash equivalents and short-term investments	115.2								115.2
Working capital	164.4								$ 164.4
Maturity Threshold Of Investments Classified To Cash Equivalents									90
Letters of Credit Outstanding, Amount	0.7				0.7				$ 0.7	0.7
Money back guarantee period (days)									30 days
Revenues	$ 130.8	$ 105.2	$ 93.2	$ 72.8	$ 84.3	$ 69	$ 58.8	$ 47.1
Computer Equipment [Member]
Organization And Summary Of Significant Accounting Policies [Line Items]
Property, Plant and Equipment, Useful Life									3 years
Machinery and Equipment [Member]
Organization And Summary Of Significant Accounting Policies [Line Items]
Property, Plant and Equipment, Useful Life									4 years
Furniture and Fixtures [Member]
Organization And Summary Of Significant Accounting Policies [Line Items]
Property, Plant and Equipment, Useful Life									5 years
Customer [Member]
Organization And Summary Of Significant Accounting Policies [Line Items]
Concentration Risk, Percentage									10.00%
Byram [Member]
Organization And Summary Of Significant Accounting Policies [Line Items]
Revenues									$ 74.1	$ 46.1	$ 24.3
Concentration Risk, Percentage									18.00%	18.00%	15.00%
Edgepark [Member]
Organization And Summary Of Significant Accounting Policies [Line Items]
Revenues									$ 42.6	$ 28.1	$ 23.1
Concentration Risk, Percentage									11.00%	11.00%	14.00%
Series of Individually Immaterial Business Acquisitions [Member]
Organization And Summary Of Significant Accounting Policies [Line Items]
Entity Number of Employees	10								10

Organization and Summary of S30

Organization and Summary of Significant Accounting Policies Organization and Summary of Significant Accounting Policies - Concentration of Credit Risk (Detail)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Customer [Member]
Entity Wide Accounts Receivable By Major Customer Percentage	23.00%	23.00%
Customer B [Member]
Entity Wide Accounts Receivable By Major Customer Percentage	13.00%	12.00%

Organization and Summary of S31

Organization and Summary of Significant Accounting Policies Organization and Significant Accounting Policies - Segment Reporting and Geographic Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Revenues from External Customers and Long-Lived Assets [Line Items]
Number of Reportable Segments	1
Revenue, Percentage	100.00%	100.00%
Total Revenue	$ 402	$ 259.2	$ 160
UNITED STATES
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue, Percentage	86.00%	86.00%
Total Revenue	$ 347.4	$ 224.2
International [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue, Percentage	14.00%	14.00%	10.00%
Total Revenue	$ 54.6	$ 35
Maximum [Member] | All Countries [Domain]
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue, Percentage	10.00%

Net Loss Per Common Share - His

Net Loss Per Common Share - Historical Outstanding Anti-Dilutive Securities (Detail) - shares shares in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Outstanding anti-dilutive securities	5.4	7.3	9.4
Options outstanding to purchase common stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Outstanding anti-dilutive securities	1.3	3.1	5.8
Unvested restricted stock units
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Outstanding anti-dilutive securities	4.1	4.2	3.6

Financial Statement Details - S

Financial Statement Details - Short Term Marketable Securities, Available for Sale (Detail) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Financial Statement Details [Line Items]
Amortized Cost	$ 29.1	$ 11.8
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Estimated Market Value	29.1	11.8
U.S. government agencies [Member]
Financial Statement Details [Line Items]
Amortized Cost	22.1	9.1
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Estimated Market Value	22.1	9.1
Corporate debt [Member]
Financial Statement Details [Line Items]
Amortized Cost	4.9	2.3
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Estimated Market Value	4.9	2.3
Commercial paper [Member]
Financial Statement Details [Line Items]
Amortized Cost	2.1	0.4
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Estimated Market Value	$ 2.1	$ 0.4

Financial Statement Details Fin

Financial Statement Details Financial Statement Details - Accounts Receivable (Details) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Accounting Policies [Abstract]
Accounts Receivable, Gross	$ 82	$ 46.8
Allowance for Doubtful Accounts Receivable	(7.9)	(4.4)
Accounts Receivable, Net	$ 74.1	$ 42.4

Financial Statement Details - I

Financial Statement Details - Inventory (Detail) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Disclosure of Financial Statement Details [Abstract]
Raw materials	$ 16	$ 7.6
Work-in-process	2.6	1
Finished goods	16.6	7.4
Total	$ 35.2	$ 16

Financial Statement Details F36

Financial Statement Details Financial Statement Details - Property and Equipment (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Property, Plant and Equipment [Line Items]
Property and Equipment, Gross	$ 92.9	$ 64
Accumulated Depreciation and Amortization	(38.2)	(32.8)
Property and equipment, net	54.7	31.2
Depreciation	10.2	7.8	$ 6.4
Furniture and Fixtures [Member]
Property, Plant and Equipment [Line Items]
Property and Equipment, Gross	3.7	3.9
Computer Equipment [Member]
Property, Plant and Equipment [Line Items]
Property and Equipment, Gross	21	18.9
Equipment [Member]
Property, Plant and Equipment [Line Items]
Property and Equipment, Gross	47.2	26.5
Property, Plant and Equipment, Type [Domain]
Property, Plant and Equipment [Line Items]
Property and Equipment, Gross	$ 21	$ 14.7

Financial Statement Details F37

Financial Statement Details Financial Statement Details - Schedule of Goodwill and Intangible Assets (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Net	$ 2.1
Amortization of Intangible Assets	0.5	$ 0.6	$ 0.6
Impairment of Intangible Assets, Finite-lived		0.2
Intangible Assets Not Subject To Amortization [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Net	3.8	3.5
Intangible Assets Not Subject To Amortization [Member] | In Process Research and Development [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Net		0.2
Intangible Assets Not Subject To Amortization [Member] | Trademarks and Trade Names [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Net	0.1	0.1
Intangible Assets Not Subject To Amortization [Member] | Goodwill [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Net	3.7	3.2
Intangible Assets Subject To Amortization [Member]
Finite-Lived Intangible Assets [Line Items]
Finite-Lived Intangible Assets, Gross	4.2	4
Finite-Lived Intangible Assets, Accumulated Amortization	(2.1)	(1.6)
Finite-Lived Intangible Assets, Net	$ 2.1	$ 2.4
Intangible Assets Subject To Amortization [Member] | Developed Technology Rights [Member]
Finite-Lived Intangible Assets [Line Items]
Finite Lived Intangible Asset Weighted Average Amortization Period	109 months	109 months
Finite-Lived Intangible Assets, Gross	$ 3.2	$ 3.2
Finite-Lived Intangible Assets, Accumulated Amortization	(1.5)	(1.2)
Finite-Lived Intangible Assets, Net	$ 1.7	$ 2
Intangible Assets Subject To Amortization [Member] | Customer-Related Intangible Assets [Member]
Finite-Lived Intangible Assets [Line Items]
Finite Lived Intangible Asset Weighted Average Amortization Period	70 months	70 months
Finite-Lived Intangible Assets, Gross	$ 0.6	$ 0.6
Finite-Lived Intangible Assets, Accumulated Amortization	(0.4)	(0.3)
Finite-Lived Intangible Assets, Net	$ 0.2	$ 0.3
Intangible Assets Subject To Amortization [Member] | Covenants Not To Compete [Member]
Finite-Lived Intangible Assets [Line Items]
Finite Lived Intangible Asset Weighted Average Amortization Period	70 months	70 months
Finite-Lived Intangible Assets, Gross	$ 0.2	$ 0.2
Finite-Lived Intangible Assets, Accumulated Amortization	(0.1)	(0.1)
Finite-Lived Intangible Assets, Net	$ 0.1	$ 0.1
Intangible Assets Subject To Amortization [Member] | In Process Research and Development [Member]
Finite-Lived Intangible Assets [Line Items]
Finite Lived Intangible Asset Weighted Average Amortization Period	51 months
Finite-Lived Intangible Assets, Gross	$ 0.2
Finite-Lived Intangible Assets, Accumulated Amortization	(0.1)
Finite-Lived Intangible Assets, Net	$ 0.1

Financial Statement Details F38

Financial Statement Details Financial Statement Details - Schedule of Future Amortization Expense (Details) $ in Millions	Dec. 31, 2015USD ($)
Disclosure Financial Statement Details Schedule Of Future Amortization Expense [Abstract]
Future Amortization Expense, 2016	$ 0.5
Future Amortization Expense, 2017	0.5
Future Amortization Expense, 2018	0.3
Future Amortization Expense, 2019	0.3
Future Amortization Expense, 2020	0.3
Thereafter through 2021	0.2
Finite-Lived Intangible Assets, Net	$ 2.1

Financial Statement Details - A

Financial Statement Details - Accounts Payable and Accrued Liabilities (Detail) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Disclosure of Financial Statement Details [Abstract]
Accounts payable trade	$ 19	$ 9.9
Accrued tax, audit, and legal fees	2.1	1.6
Clinical trials	0.7	0.4
Accrued other including warranty	17.1	8.5
Total	$ 38.9	$ 20.4

Financial Statement Details F40

Financial Statement Details Financial Statement Details - Accrued Payroll and Related Expenses (Details) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Disclosure Financial Statement Details Accrued Payroll And Related Expenses [Abstract]
Accrued Vacation	$ 4.4	$ 3.2
Accrued Wages Bonus And Taxes	18.4	12.5
Accrued Employee Benefits, Current	2.1	1.5
Employee-related Liabilities	$ 24.9	$ 17.2

Financial Statement Details -41

Financial Statement Details - Accrued Warranty (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Movement in Standard Product Warranty Accrual [Roll Forward]
Beginning balance	$ 1.3	$ 0.9
Charges to costs and expenses	9	5.2
Costs incurred	(7)	(4.8)
Ending balance	$ 3.3	$ 1.3

Commitments and Contingencies -

Commitments and Contingencies - Long-Term Debt and PO Commitments (Detail) - USD ($) $ in Millions	1 Months Ended	12 Months Ended
	Nov. 30, 2012	Dec. 31, 2015	Dec. 31, 2012
Commitments and Contingencies Disclosure [Abstract]
Long-term Line of Credit	$ 15
Term Loan Debt	20
Term Loan Advances Aggregate Amount	7
Debt Instrument, Unused Borrowing Capacity, Amount	$ 13
Debt Instrument Basis Spread On Treasury Variable Rate	6.94%
Debt Instrument, Maturity Date	Nov. 1, 2016
Debt Issuance Cost			$ 1.1
Long-term Debt, Fiscal Year Maturity [Abstract]
Long-term Debt, Maturities, Repayments of Principal in Next Twelve Months		$ 2.3
Purchase commitments with vendors total		$ 49.3
Purchase commitments with vendors total maximum term, in years		1 year

Commitments and Contingencies43

Commitments and Contingencies - Rental Obligations (Detail) $ in Millions	12 Months Ended
	Dec. 31, 2015USD ($)	Dec. 31, 2014USD ($)	Dec. 31, 2013USD ($)	Oct. 01, 2014ft²
Operating Leases, Rent Expense	$ 5.6	$ 3.6	$ 3
Payments for (Proceeds from) Tenant Allowance	$ (1.8)
Potential Rental Rate Adjustment Minimum	2.50%
Potential Rental Rate Adjustment Maximum	4.00%
Operating Leases, Future Minimum Payments Due, Remainder of 2015	$ 4.8
Operating Leases, Future Minimum Payments, 2016	4.4
Operating Leases, Future Minimum Payments, 2017	5.2
Operating Leases, Future Minimum Payments, 2018	5.3
Operating Leases, Future Minimum Payments, 2019	5.3
Operating Leases, Future Minimum Payments, Thereafter	6.5
Total	$ 31.5
Leased Buildings -6340 Sequence Drive, 6310 Sequence Drive, 6290 Sequence drive [Member]
Leased Square Footage | ft²				219,000
6310,6340 and 6290 Sequence Drive Lease [Member]
Lessee Leasing Arrangements, Operating Leases, Number of Renewal Term	2
Lessee Leasing Arrangements, Operating Leases, Renewal Term	5 years

Development and Other Agreeme44

Development and Other Agreements - Additional Information (Detail) - USD ($)	1 Months Ended			3 Months Ended	12 Months Ended
	Jul. 31, 2014	Jul. 31, 2013	Feb. 29, 2012	Dec. 31, 2015	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Aug. 10, 2015	Feb. 01, 2012
Development Agreements [Line Items]
Issuance of common stock related to Verily Collaboration Agreement					$ 36,500,000
Development grant and other revenue					1,300,000	$ 2,100,000	$ 2,900,000
Research and Development Arrangement, Value of Grant		$ 4,000,000
Research and Development Arrangement, Grants Received During Period					1,000,000	2,500,000	$ 500,000
Option One [Member]
Development Agreements [Line Items]
Royalty Guarantees, Commitments, Commitment Period		4 years
Option Two [Member]
Development Agreements [Line Items]
Royalty Guarantees, Commitments, Amount		$ 6,000,000
Option One [Member]
Development Agreements [Line Items]
Royalty Guarantees, Commitments, Amounts, Per Year		$ 2,000,000
Tandem Diabetes Care, Inc. [Member]
Development Agreements [Line Items]
Development grant and other revenue						$ 500,000
Collaborative Arrangement, Royalty per Product Sold					100
Collaborative Arrangement, Marketing Funds per Product Sold					100
Tandem Diabetes Care, Inc. [Member] | Maximum [Member]
Development Agreements [Line Items]
Third party contribution to off set expenses									$ 1,000,000
Tandem Diabetes Care, Inc. [Member] | Collaborative Arrangement, Initial Payment [Member]
Development Agreements [Line Items]
One-time milestone payment, received			$ 1,000,000
Regulatory Submission Milestone [Member] | Tandem Diabetes Care, Inc. [Member]
Development Agreements [Line Items]
Additional milestone payments	$ 1,000,000
Regulatory Approval Milestone [Member] [Member] | Tandem Diabetes Care, Inc. [Member]
Development Agreements [Line Items]
Additional milestone payments					1,000,000
Verily Life Sciences [Member] | Collaborative Arrangement [Member]
Development Agreements [Line Items]
Collaborative Arrangement, Royalty Eligible Sales					$ 750,000,000
Collaborative Arrangement, Commitment Amount, Royalty Eligible Sales Threshold Not Achieved								$ 0
Verily Life Sciences [Member] | Collaborative Arrangement [Member] | Collaborative Arrangement, Milestone Payments [Member]
Development Agreements [Line Items]
Collaborative Arrangement, Development & Regulatory Milestones								65,000,000
Verily Life Sciences [Member] | Collaborative Arrangement [Member] | Collaborative Arrangement, Initial Payment [Member]
Development Agreements [Line Items]
Collaborative Arrangement, Upfront Fee								$ 35,000,000
Issuance of common stock related to Verily Collaboration Agreement, shares				404,591
Share Price								$ 90.29
Research and Development Expense [Member] | Verily Life Sciences [Member] | Collaborative Arrangement [Member] | Collaborative Arrangement, Initial Payment [Member]
Development Agreements [Line Items]
Issuance of common stock related to Verily Collaboration Agreement				$ 36,500,000

Fair Value Measurements (Detail

Fair Value Measurements (Details) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash Equivalents, at Carrying Value	$ 32.1	$ 54.3
Available-for-sale Securities, Debt Securities, Current	29.1	11.8
Restricted cash		1
Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash Equivalents, at Carrying Value	0	0
Available-for-sale Securities, Debt Securities, Current	0	0
Restricted cash		1
Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash Equivalents, at Carrying Value	32.1	54.3
Available-for-sale Securities, Debt Securities, Current	29.1	11.8
Restricted cash		0
Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash Equivalents, at Carrying Value	0	0
Available-for-sale Securities, Debt Securities, Current	0	0
Restricted cash		0
U.S. government agencies [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities, Debt Securities, Current	22.1	9.1
U.S. government agencies [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities, Debt Securities, Current	0	0
U.S. government agencies [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities, Debt Securities, Current	22.1	9.1
U.S. government agencies [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities, Debt Securities, Current	0	0
Corporate debt [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities, Debt Securities, Current	4.9	2.3
Corporate debt [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities, Debt Securities, Current	0	0
Corporate debt [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities, Debt Securities, Current	4.9	2.3
Corporate debt [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities, Debt Securities, Current	0	0
Commercial paper [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities, Debt Securities, Current	2.1	0.4
Commercial paper [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities, Debt Securities, Current	0	0
Commercial paper [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities, Debt Securities, Current	2.1	0.4
Commercial paper [Member] | Fair Value, Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities, Debt Securities, Current	$ 0	$ 0

Income Taxes - Additional Infor

Income Taxes - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Operating Loss Carryforwards [Line Items]
Income tax expense	$ (0.1)	$ (0.1)	$ 0
Tax Credit Carryforward, Expiration Date	Jan. 1, 2019
Tax credit carryforwards subject to expiration	$ 2.1
Net operating losses and tax credit carryforwards, limitations on use, ownership changes	50.00%
Net operating losses and tax credit carryforwards, limitations on use, ownership change period (years)	3 years
Valuation allowance amount	$ 196.4	$ 169
Share-based compensation, excess tax benefits	131.9
Unrecognized tax benefits	0
Undistributed Earnings of Foreign Subsidiaries	0.5
Federal [Member]
Operating Loss Carryforwards [Line Items]
Operating Loss Carryforwards	$ 675.1
Operating Loss Carryforwards, Expiration Dates	Jan. 1, 2019
Deferred Tax Assets, Tax Credit Carryforwards, Research	$ 18.5
State and Local Jurisdiction [Member]
Operating Loss Carryforwards [Line Items]
Operating Loss Carryforwards	$ 424.3
Operating Loss Carryforwards, Expiration Dates	Jan. 1, 2016
Deferred Tax Assets, Tax Credit Carryforwards, Research	$ 20.5

Income Taxes - Deferred Tax Ass

Income Taxes - Deferred Tax Assets and Liabilities (Detail) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Summary Of Net Deferred Tax Assets [Line Items]
Net operating loss carryforwards	$ 127.6	$ 132.2
Capitalized research and development expenses	17	5
Tax credits	19.1	9
Share-based compensation	20.8	15.5
Fixed and intangible assets	(1.3)	1.2
Other, net	13.9	7
Total gross deferred tax assets	197.1	169.9
Less: valuation allowance	(196.4)	(169)
Deferred tax liability related to acquired intangibles assets	(0.8)	(1)
Net deferred tax liability	$ (0.1)	$ (0.1)

Income Taxes - Reconciliation B

Income Taxes - Reconciliation Between Effective Tax Rate and Statutory Rate (Detail)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Reconciliation Of Statutory Federal Tax Rate [Line Items]
Income taxes at statutory rates	35.00%	35.00%	35.00%
State income tax, net of federal benefit	1.72%	(1.56%)	2.70%
Permanent items	(0.55%)	(0.80%)	(3.64%)
Research and development credits	17.40%	7.50%	6.17%
Stock and officers compensation	(5.37%)	(15.93%)	(2.23%)
Rate change	(0.30%)	(1.66%)	7.11%
Other	(0.36%)	(3.97%)	0.08%
Change in valuation allowance	(47.73%)	(19.24%)	(45.15%)
Income taxes at effective rates	(0.19%)	(0.66%)	0.04%

Income Taxes - Summary of Unrec

Income Taxes - Summary of Unrecognized Tax Benefits (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Reconciliation Of Unrecognized Tax Benefits [Line Items]
Beginning Balance	$ 7.6	$ 6.2	$ 4.8
Unrecognized Tax Benefits, Increase Resulting from Prior Period Tax Positions	2.6		0.5
Unrecognized Tax Benefits, Income Tax Penalties Expense	0
Increases related to current year tax positions	5.4	1.4	0.9
Ending Balance	$ 15.6	$ 7.6	$ 6.2

Income Taxes Net Operating Loss

Income Taxes Net Operating Loss Carryforwards (Details) $ in Millions	12 Months Ended
	Dec. 31, 2015USD ($)
Operating Loss Carryforwards [Line Items]
Tax Credit Carryforward, Expiration Date	Jan. 1, 2019
State and Local Jurisdiction [Member]
Operating Loss Carryforwards [Line Items]
Net Operating Loss Carryforwards Expiring In 2016	$ 0.7
California Franchise Tax Board [Member]
Operating Loss Carryforwards [Line Items]
Net Operating Loss Carryforwards Expiring In 2016	39.6
Net Operating Loss Carryforwards Expiring In 2017	14.1
Federal [Member]
Operating Loss Carryforwards [Line Items]
Operating Loss Carryforwards	$ 675.1
Operating Loss Carryforwards, Expiration Dates	Jan. 1, 2019
Deferred Tax Assets, Tax Credit Carryforwards, Research	$ 18.5
State and Local Jurisdiction [Member]
Operating Loss Carryforwards [Line Items]
Operating Loss Carryforwards	$ 424.3
Operating Loss Carryforwards, Expiration Dates	Jan. 1, 2016
Deferred Tax Assets, Tax Credit Carryforwards, Research	$ 20.5
California Franchise Tax Board [Member]
Operating Loss Carryforwards [Line Items]
Net Operating Loss Carryforwards Expiring In Year Thirteen and Thereafter	$ 321.8

Employee Benefit Plans - Additi

Employee Benefit Plans - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	May. 28, 2015
Maximum employee contribution percentage	90.00%
Maximum payroll deductions, percentage	10.00%
Employee purchase price floor, percentage	85.00%
Offering period (months)	12 months
Offering periods, frequency (months)	6 months
Number of purchase periods within an offering period	2
Purchase Period Months	6 months
Purchase date, frequency (months)	6 months
Stock Issued During Period, Shares, Employee Stock Purchase Plans	115,848	135,057	199,661
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized				4,000,000
Vesting period, maximum, years	10 years
Equity Incentive Plan fair market value on grant date floor, percentage	100.00%
In-the-money options, maximum exercise price	$ 81.90
Options in-the-money, number	1,300,000
Options in-the-money, exercisable, number	1,300,000
Unrecognized compensation cost	$ 151.8
Minimum [Member]
Vesting period, years	3 years
Maximum [Member]
Vesting period, years	4 years
Restricted Stock [Member]
Weighted average fair value of options granted	$ 63.63	$ 46.19	$ 17.29
Total fair value of RSUs vested	$ 60	$ 27	$ 17.5
Restricted Stock [Member] | Minimum [Member]
Vesting period, years	3 years
Restricted Stock [Member] | Maximum [Member]
Vesting period, years	4 years

Employee Benefit Plans - Summar

Employee Benefit Plans - Summary of Stock Option Activity (Detail) $ / shares in Thousands, shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2015USD ($)$ / sharesshares
Schedule Of Stock Options [Line Items]
Outstanding, Beginning | shares	3.1
Exercised, Number of Shares | shares	(1.8)
Cancelled, Number of Shares | shares	0
Outstanding, Ending | shares	1.3
Exercisable, Number of Shares | shares	1.3
Outstanding, Weighted-Average Exercise Price | $ / shares	$ 7,950
Exercised, Weighted-Average Exercise Price | $ / shares	8,220
Cancelled, Weighted-Average Exercise Price | $ / shares	0
Outstanding, Weighted-Average Exercise Price | $ / shares	7,560
Exercisable, Weighted-Average Exercise Price | $ / shares	$ 7,560
Outstanding, Weighted-Average Remaining Contractual Term (years)	2 years 11 months 15 days
Exercisable, Weighted-Average Remaining Contractual Term (years)	2 years 11 months 15 days
Outstanding, Aggregate Intrinsic Value | $	$ 94.5
Exercisable, Aggregate Intrinsic Value | $	$ 94.5

Employee Benefit Plans - Schedu

Employee Benefit Plans - Schedule of Intrinsic Value of Options Exercised and Fair Value of Options Vested (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Intrinsic value of options exercised	$ 125.8	$ 99	$ 29.8
Fair value of options vested	$ 0	$ 0.4	$ 1.3

Employee Benefit Plans - Sche54

Employee Benefit Plans - Schedule of Share Based Compensation Expenses (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Share-based compensation expense included in operating expenses	$ 82.7	$ 50	$ 24.6
Cost of sales [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Share-based compensation expense included in operating expenses	8.1	4.5	2.6
Research and development [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Share-based compensation expense included in operating expenses	28.5	17	8.5
Selling, general and administrative [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Share-based compensation expense included in operating expenses	$ 46.1	$ 28.5	$ 13.5

Employee Benefit Plans - Sche55

Employee Benefit Plans - Schedule of Valuation Assumptions for Each Option Grant and Employee Stock Purchase Plan Purchase Rights (Detail) - Employee Stock Purchase Plan [Member]	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Dividend yield	0.00%	0.00%	0.00%
Expected life (in years)	1 year	1 year	1 year
Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Risk free interest rate	0.15%	0.10%	0.13%
Expected volatility of the Company's stock	0.30%	0.41%	0.30%
Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Risk free interest rate	0.25%	0.12%	0.17%
Expected volatility of the Company's stock	0.44%	0.50%	0.39%

Employee Benefit Plans - Sche56

Employee Benefit Plans - Schedule of Restricted Stock Units Activity (Detail) $ / shares in Thousands, shares in Millions	12 Months Ended
	Dec. 31, 2015$ / sharesshares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Outstanding,Shares	4.2
Outstanding, Shares	4.1
Unvested restricted stock units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Outstanding,Shares	4.2
Granted, Shares	2.1
Vested, Shares	(2)
Forfeited, Shares	(0.2)
Outstanding, Shares	4.1
Outstanding, Weighted Average Grant Date Fair Value | $ / shares	$ 33,350
Granted, Weighted Average Grant Date Fair Value | $ / shares	63,630
Vested, Weighted Average Grant Date Fair Value | $ / shares	29,480
Forfeited, Weighted Average Grant Date Fair Value | $ / shares	32,620
Outstanding, Weighted Average Grant Date Fair Value | $ / shares	50,600
Outstanding, Aggregate Intrinsic Value | $ / shares	$ 339,000

Employee Benefit Plans - Sche57

Employee Benefit Plans - Schedule of Stock Options Reserved for Future Issuance (Detail) - shares shares in Millions	Dec. 31, 2015	Dec. 31, 2014
Stock options granted and outstanding	1.3	3.1
Unvested RSUs	4.1	4.2
Reserved for future grant	3.7	0.3
Employee Stock Purchase Plan	1.5	2.5
Total	10.6	10.1

Quarterly Financial Informati58

Quarterly Financial Information - Schedule of Quarterly Financial Information (Detail) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Quarterly Financial Data [Line Items]
Revenues	$ 130.8	$ 105.2	$ 93.2	$ 72.8	$ 84.3	$ 69	$ 58.8	$ 47.1
Gross profit	91.2	74.7	66	46.5	59.4	47.2	39.9	29.8	$ 278.4	$ 176.3	$ 100.1
Total operating costs	89.6	117.1	69.6	59.2	57.8	52.2	45.7	42.1	335.5	197.8	129
Net loss	$ 1.5	$ (42.5)	$ (3.7)	$ (12.9)	$ 1.3	$ (5.2)	$ (6)	$ (12.5)	$ (57.6)	$ (22.4)	$ (29.8)
Income (Loss) from Continuing Operations, Per Basic Share	$ 0.02	$ (0.53)	$ (0.05)	$ (0.17)	$ 0.02	$ (0.07)	$ (0.08)	$ (0.17)
Income (Loss) from Continuing Operations, Per Diluted Share	$ 0.02	$ (0.53)	$ (0.05)	$ (0.17)	$ 0.02	$ (0.08)	$ (0.09)	$ (0.17)

Valuation and Qualifying Acco59

Valuation and Qualifying Accounts (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Allowance for doubtful accounts
Balance, beginning	$ 4.3	$ 2.6	$ 1.2
Provision for doubtful accounts	7.8	4	2.7
Write-off and adjustments	(4.5)	(2.6)	(1.4)
Recoveries	0.2	0.3	0.1
Balance, ending	$ 7.8	$ 4.3	$ 2.6

Subsequent Events Subsequent 60

Subsequent Events Subsequent Events (Details) $ in Millions	Feb. 01, 2016USD ($)ft²	Dec. 31, 2015USD ($)
Subsequent Event [Line Items]
Operating Leases, Future Minimum Payments, Due in Two Years		$ 4.4
Operating Leases, Future Minimum Payments, Due in Three Years		5.2
Operating Leases, Future Minimum Payments, Due in Four Years		5.3
Operating Leases, Future Minimum Payments, Due in Five Years		5.3
Operating Leases, Future Minimum Payments, Due Thereafter		6.5
Total		$ 31.5
Subsequent Event [Member]
Subsequent Event [Line Items]
Security Deposit	$ 0.3
Operating Leases, Future Minimum Payments, 2016	0.8
Operating Leases, Future Minimum Payments, Due in Two Years	1.5
Operating Leases, Future Minimum Payments, Due in Three Years	2.2
Operating Leases, Future Minimum Payments, Due in Four Years	2.9
Operating Leases, Future Minimum Payments, Due in Five Years	3.4
Operating Leases, Future Minimum Payments, Due Thereafter	3.8
Total	$ 14.6
Leased Buildings -6350 Sequence Drive [Member] | Subsequent Event [Member]
Subsequent Event [Line Items]
Leased Square Footage | ft²	132,600