DexCom (DXCM) 10-Q 6 Nov 14 2014 Q3 Quarterly report Financial data

Document_and_Entity_Informatio

Document and Entity Information	9 Months Ended
	Sep. 30, 2014	Nov. 01, 2014
Entity Information [Line Items]	'	'
Document Type	'10-Q	'
Amendment Flag	'false	'
Document Period End Date	30-Sep-14	'
Document Fiscal Year Focus	'2014	'
Document Fiscal Period Focus	'Q3	'
Trading Symbol	'DXCM	'
Entity Registrant Name	'DEXCOM INC	'
Entity Central Index Key	'0001093557	'
Current Fiscal Year End Date	'--12-31	'
Entity Filer Category	'Large Accelerated Filer	'
Entity Common Stock, Shares Outstanding	'	76,561,868

Consolidated_Balance_Sheets

Consolidated Balance Sheets (USD $)	Sep. 30, 2014	Dec. 31, 2013
In Millions, unless otherwise specified
Current assets:	'	'
Cash and cash equivalents	$63.20	$43.20
Short-term marketable securities, available-for-sale	11.7	11.4
Accounts receivable, net	31.4	26.1
Inventory	14.3	9
Prepaid and other current assets	2.8	3.4
Total current assets	123.4	93.1
Property and equipment, net	28	20.7
Restricted cash	1	1
Intangible assets, net	3.1	3.6
Goodwill	3.2	3.2
Other assets	0.7	0.9
Total assets	159.4	122.5
Current liabilities:	'	'
Accounts payable and accrued liabilities	20.9	14.1
Accrued payroll and related expenses	16.8	15.1
Current portion of long-term debt	2.3	2.2
Current portion of deferred revenue	0.6	0.7
Total current liabilities	40.6	32.1
Other liabilities	0.9	1.7
Long-term debt, net of current portion	2.9	4.6
Total liabilities	44.4	38.4
Commitments and contingencies (Note 4)	'	'
Stockholders' equity:	'	'
Preferred stock, $0.001 par value, 5.0 shares authorized; no shares issued and outstanding at September 30, 2014 and December 31, 2013, respectively	0	0
Common stock, $0.001 par value, 100.0 authorized; 76.7 and 76.4 issued and outstanding, respectively, at September 30, 2014; and 72.8 and 72.5 shares issued and outstanding, respectively, at December 31, 2013	0.1	0.1
Additional paid-in capital	614.1	559.5
Accumulated other comprehensive loss	-0.1	-0.1
Accumulated deficit	-499.1	-475.4
Total stockholders’ equity	115	84.1
Total liabilities and stockholders’ equity	$159.40	$122.50

Consolidated_Balance_Sheets_Pa

Consolidated Balance Sheets (Parenthetical) (USD $)	Sep. 30, 2014	Dec. 31, 2013
Statement of Financial Position [Abstract]	'	'
Preferred stock, par value (in usd per share)	$0.00	$0.00
Preferred stock, shares authorized (in shares)	5,000,000	5,000,000
Preferred stock, shares issued (in shares)	0	0
Preferred stock, shares outstanding (in shares)	0	0
Common stock, par value (in usd per share)	$0.00	$0.00
Common stock, shares authorized (in shares)	100,000,000	100,000,000
Common stock, shares issued (in shares)	76,700,000	72,800,000
Common stock, shares outstanding (in shares)	76,400,000	72,500,000

Consolidated_Statements_of_Ope

Consolidated Statements of Operations (USD $)	3 Months Ended		9 Months Ended
In Millions, except Per Share data, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Product revenue	$67.90	$42.50	$172.80	$105.80
Development grant and other revenue	1.1	0.4	2.1	2.5
Total revenue	69	42.9	174.9	108.3
Product cost of sales	21.8	14.8	57.4	40.9
Development and other cost of sales	0	0.5	0.6	1.4
Total cost of sales	21.8	15.3	58	42.3
Gross profit	47.2	27.6	116.9	66
Operating expenses	'	'	'	'
Research and development	18.5	11.8	47.8	32.2
Selling, general and administrative	33.7	21.6	92.2	60.4
Total operating expenses	52.2	33.4	140	92.6
Operating loss	-5	-5.8	-23.1	-26.6
Interest expense	-0.2	-0.2	-0.6	-0.6
Net loss	($5.20)	($6)	($23.70)	($27.20)
Basic net loss per share	($0.07)	($0.08)	($0.32)	($0.38)
Shares used to compute basic net loss per share	75.8	71.4	74.7	70.7
Diluted net loss per share	($0.08)	($0.08)	($0.33)	($0.38)
Shares used to compute diluted net loss per share	76.1	71.4	75	70.7

Consolidated_Statements_of_Com

Consolidated Statements of Comprehensive Loss (USD $)	3 Months Ended		9 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Net loss	($5.20)	($6)	($23.70)	($27.20)
Unrealized gain (loss) on short-term available-for-sale marketable securities	0	0	0	0
Foreign currency translation gain (loss)	0.1	0	0	0
Comprehensive loss	($5.10)	($6)	($23.70)	($27.20)

Consolidated_Statements_of_Cas

Consolidated Statements of Cash Flows (USD $)	9 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013
Operating activities	'	'
Net loss	($23.70)	($27.20)
Adjustments to reconcile net loss to cash used in operating activities:	'	'
Depreciation and amortization	6	5.1
Share-based compensation	35.7	18
Accretion and amortization related to marketable securities, net	0.1	0.3
Amortization of debt issuance costs	0.3	0.3
Change in fair value of contingent consideration	-0.7	2
Changes in operating assets and liabilities:	'	'
Accounts receivable, net	-5.3	-2
Inventory	-5.3	-2.5
Prepaid and other assets	0.7	-0.5
Accounts payable and accrued liabilities	6.1	2.9
Accrued payroll and related expenses	1.7	3.1
Deferred revenue	-0.1	-1.4
Deferred rent and other liabilities	-0.3	-0.1
Net cash provided by (used in) operating activities	15.2	-2
Investing activities	'	'
Purchase of available-for-sale marketable securities	-10.3	-12.4
Proceeds from the maturity of available-for-sale marketable securities	9.8	38.4
Purchase of property and equipment	-11.6	-5.6
Net cash provided by (used in) investing activities	-12.1	20.4
Financing activities	'	'
Net proceeds from issuance of common stock	18.5	6.9
Repayment of long-term debt	-1.6	0
Net cash provided by financing activities	16.9	6.9
Increase in cash and cash equivalents	20	25.3
Cash and cash equivalents, beginning of period	43.2	8.1
Cash and cash equivalents, end of period	$63.20	$33.40

Organization_and_Summary_of_Si

Organization and Summary of Significant Accounting Policies	9 Months Ended
	Sep. 30, 2014
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 $499.1 million at September 30, 2014. As of September 30, 2014, we had available cash, cash equivalents and short-term marketable securities totaling $74.9 million, excluding $1.0 million of restricted cash, and working capital of $82.8 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 related expenses or other operating expenses 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 September 30, 2015.
	We have prepared the accompanying unaudited consolidated financial statements in accordance with accounting principles generally accepted in the United States of America (“U.S. GAAP”) for interim financial information and with the instructions to Form 10-Q and Article 10 of Regulation S-X. Accordingly, they do not include all of the information and disclosures required by U.S. GAAP for complete financial statements. In the opinion of management, all adjustments, which include only normal recurring adjustments considered necessary for a fair presentation (except for the changes in estimates described below), have been included. Operating results for the three and nine months ended September 30, 2014 are not necessarily indicative of the results that may be expected for the year ending December 31, 2014. These unaudited consolidated financial statements should be read in conjunction with the audited financial statements and related notes thereto for the year ended December 31, 2013 included in the Annual Report on Form 10-K filed by us with the Securities and Exchange Commission on February 20, 2014.
	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
	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 as, one operating segment.
	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, employee bonus, clinical trial expenses, allowance for bad debt, accounting for the SweetSpot acquisition including contingent consideration, and share-based compensation expense.
	Share-Based Compensation
	We recorded $13.8 million and $35.7 million in share-based compensation expense during the three and nine months ended September 30, 2014, respectively, compared to $6.6 million and $18.0 million, respectively, during the three and nine months ended September 30, 2013. At September 30, 2014, unrecognized estimated compensation costs related to unvested stock options and restricted stock units totaled $116.6 million and are expected to be recognized through 2018. We issued performance restricted stock units (the “Performance Awards”) in connection with our acquisition of SweetSpot in March 2012. The performance targets for these Performance Awards are tied to earnings before interest, taxes, depreciation and amortization (“EBITDA”) for fiscal years 2013 and 2014. We recognize expense for the Performance Awards when it is probable that the EBITDA targets will be met. The performance target for fiscal 2013 EBITDA was not achieved. At September 30, 2014, we had $2.2 million of unrecognized share-based compensation expense related to the Performance Awards for the fiscal 2014 performance target. We use the grant date fair value of our common stock for valuing restricted stock unit awards. Our determination of the fair value of share-based payment awards on the date of grant is affected by our stock price. Compensation costs will be adjusted for future changes in estimated forfeitures.
	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 and Latin America. 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, data management software and a USB cable. Disposable sensors for use with the durable system are sold separately in packages of four. 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 by reducing revenues and establishing a liability account at the time of shipment based on historical experience. Returns have historically been immaterial.
	We have entered into distribution agreements with Byram Healthcare and their subsidiaries ("Byram"), RGH Enterprises, Inc. (“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 (“Stocking Distributors”), whereby the 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 (“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 Freight on Board (“FOB”) shipping point (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.
	We have collaborative license and development arrangements with strategic partners for the development and commercialization of products utilizing our technologies. The terms of these agreements typically include the license of certain intellectual property rights and the provision of multiple deliverables by us (for example, research and development services, product prototypes and products for use in clinical trials) in exchange for consideration to us of some combination of non-refundable license fees, funding of research and development activities, payments based upon achievement of development milestones and royalties in the form of a designated percentage of product sales or profits. With the exception of royalties, these types of consideration are classified as development grant and other revenue in our consolidated statements of operations and are generally recognized over the service period except for substantive milestone payments, which are generally recognized when the milestone is achieved. In determining whether each milestone is substantive, we considered whether the consideration earned by achieving the milestone should (i) be commensurate with either (a) our performance to achieve the milestone or (b) the enhancement of value of the item delivered as a result of a specific outcome resulting from our performance to achieve the milestone, (ii) relate solely to past performance and (iii) be reasonable relative to all deliverables and payment terms in the arrangement. We recognize royalties in the period in which we obtain the royalty report, which is necessary to determine the amount of royalties we are entitled to receive.
	Non-refundable license fees are recognized as revenue when we have a contractual right to receive such payment, the contract price is fixed or determinable, the collection of the resulting receivable is reasonably assured and we have no further performance obligations under the license agreement. Multiple element arrangements, such as license, development and other multiple element service arrangements are analyzed to determine how the arrangement consideration should be allocated among the separate units of accounting, or whether they must be accounted for as a single unit of accounting.
	For transactions containing multiple element arrangements, we consider deliverables as separate units of accounting and recognize deliverables as revenue upon delivery only if (i) the deliverable has standalone value and (ii) if the arrangement includes a general right of return relative to the delivered item(s), delivery or performance of the undelivered item(s) is probable and substantially controlled by us. We allocate consideration to the separate units of accounting using the relative selling price method, in which allocation of consideration is based on vendor-specific objective evidence (“VSOE”) if available, third-party evidence (“TPE”), or if VSOE and TPE are not available, management’s best estimate of a standalone selling price for elements.
	We use judgment in estimating the value allocable to the deliverables in an agreement based on our estimate of the fair value or relative selling price attributable to the related deliverables and the consideration from such an agreement is typically recognized as product revenue or development grant and other revenue. For arrangements that are accounted for as a single unit of accounting, total payments under the arrangement are recognized as revenue on a straight-line basis over the period we expect to complete our performance obligations. We review the estimated period of our performance obligations on a periodic basis and update the recognition period as appropriate. The cumulative amount of revenue earned is limited to the cumulative amount of payments we are entitled to as of the period ending date.
	If we cannot reasonably estimate when our performance obligation either ceases or becomes inconsequential, then revenue is deferred until we can reasonably estimate when the performance obligation ceases or becomes inconsequential. Revenue is then recognized over the remaining estimated period of performance. Deferred revenue amounts are classified as current liabilities to the extent that revenue is expected to be recognized within one year.
	Significant management judgment is required in determining the level of effort required under an arrangement and the period over which we are expected to complete our performance obligations under an arrangement.
	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.
	Foreign Currency
	The financial statements of our non-U.S. subsidiary, 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 income 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 other 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.
	Short-Term Marketable Securities
	We have classified our short-term marketable securities as “available-for-sale” and carry them 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 do not 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 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 base the fair value of our Level 1 financial instruments that are in active markets using quoted market prices for identical instruments. Our Level 1 financial instruments include certificates of deposit.
	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.
	Certain contingent consideration liabilities are classified within Level 3 of the fair value hierarchy because they use unobservable inputs. For those liabilities, fair value is determined using a probability-weighted discounted cash flow model, the significant inputs, which include the probability and expected timing of achievement and the discount rate, are not observable in the market.
	The following table represents our fair value hierarchy for our financial assets (cash equivalents, marketable securities and restricted cash) and liabilities measured at fair value on a recurring basis as of September 30, 2014 (in millions):
		Fair Value Measurements Using
		Level 1			Level 2		Level 3			Total
	Cash equivalents	$	—		$	24.5	$	—		$	24.5
	Marketable securities, available for sale
	U.S. government agencies	—			8.8		—			8.8
	Corporate debt	—			2		—			2
	Commercial paper	—			0.9		—			0.9
	Total marketable securities, available for sale	$	—		$	11.7	$	—		$	11.7
	Restricted cash	$	1		$	—	$	—		$	1
	Contingent consideration liability	$	—		$	—	$	3.5		$	3.5
	The following table represents our fair value hierarchy for our financial assets (cash equivalents, marketable securities and restricted cash) and liabilities measured at fair value on a recurring basis as of December 31, 2013 (in millions):
		Fair Value Measurements Using
		Level 1			Level 2		Level 3			Total
	Cash equivalents	$	—		$	28.7	$	—		$	28.7
	Marketable securities, available for sale
	U.S. government agencies	—			8.9		—			8.9
	Corporate debt	—			2.5		—			2.5
	Total marketable securities, available for sale	$	—		$	11.4	$	—		$	11.4
Restricted cash	$	1		$	—	$	—		$	1
Contingent consideration liability	$	—		$	—	$	4.2		$	4.2
Additional Disclosures Regarding Fair Value Measurements
The book values of cash equivalents, short-term marketable securities, accounts receivable and accounts payable approximate their respective fair values due to the short-term nature of these instruments.
Non-Financial Assets and Liabilities Measured at Fair Value on a Nonrecurring Basis
Our non-financial assets and liabilities (e.g., goodwill, intangible assets, property and equipment and nonfinancial assets and liabilities initially measured at fair value in a business combination) are re-measured at fair value subsequent to initial recognition only when they are deemed to be other-than-temporarily impaired. There were no non-financial assets and liabilities deemed to be other-than-temporarily impaired and measured at fair value on a nonrecurring basis for the periods presented.
Contingent Consideration Liability
On February 21, 2012, we entered into an Agreement and Plan of Merger (the “Merger Agreement”) to acquire SweetSpot. The merger was consummated on March 6, 2012 (the “Closing”). In connection with the acquisition of SweetSpot, at the closing of the acquisition, we agreed to issue up to an additional 357,176 shares of our common stock to the security holders of SweetSpot (the “SweetSpot Security-holders”) upon the achievement of certain platform development milestones and regulatory approval milestones (the “Milestone Payments”), which are classified as contingent consideration. The fair value of the contingent consideration at the closing of $2.2 million was determined using a probability-weighted discounted cash flow model, the significant inputs of which are not observable in the market. The key assumptions in applying this approach are the interest rate and the estimated probabilities and timing assigned to the Milestone Payments being achieved. During 2012, approximately $1.1 million related to the contingent consideration was earned and paid through the issuance of 89,296 shares of our common stock. We did not issue any shares of common stock for Milestone Payments in 2013 or through September 30, 2014. On November 3, 2014, we entered into a Settlement Agreement with the stockholders’ agent for the SweetSpot Security-holders (the “SweetSpot Settlement Agreement), whereby we agreed to, among other things, issue 89,300 shares of our common stock in exchange for the cancellation of the remaining Milestone Payments. For details on the SweetSpot Settlement Agreement please see Note 6 "Subsequent Events."
We reassess the fair value of our contingent consideration liability on a quarterly basis. Changes in fair value are recorded in the consolidated statements of operations as research and development expense since the milestones are related to development activities.
The following table sets forth the change in the estimated fair value for our liabilities measured on a recurring basis using significant unobservable inputs (Level 3) (in millions):
	Three Months Ended					Nine Months Ended
	September 30,					September 30,
	2014			2013		2014			2013
Fair value measurement at the beginning of period	$	4.4		$	2.7	$	4.2		$	1.7
Changes in fair value measurement included in operating expenses	(0.9		)	1		(0.7		)	2
Fair value measurement at end of period	$	3.5		$	3.7	$	3.5		$	3.7
The changes in the fair value of the contingent consideration for the SweetSpot acquisition for the periods presented resulted from updates to assumed probability of achievement of milestones and adjustments to the discount periods.
Impairment of Goodwill and Intangible Assets
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.
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.
Recent Accounting Guidance
In July 2013, the FASB issued authoritative guidance for Presentation of an Unrecognized Tax Benefit When a Net Operating Loss Carryforward, a Similar Tax Loss, or a Tax Credit Carryforward Exists, which provides explicit guidance on the financial statement presentation of an unrecognized tax benefit when a net operating loss carryforward, a similar tax loss, or a tax credit carryforward exists. The guidance is effective prospectively for fiscal years, and interim periods within those years, beginning after December 15, 2013, with early adoption permitted. We adopted this guidance on January 1, 2014, and the adoption of this guidance did not have a material impact on our consolidated financial statements or related financial statement disclosures.
In May 2014, the 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 2017. 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.

Net_Loss_Per_Common_Share

Net Loss Per Common Share	9 Months Ended
	Sep. 30, 2014
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, options, unvested restricted stock units settleable in shares of common stock and contingently issuable shares related to contingent consideration for the SweetSpot acquisition 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. The dilutive effect of the contingent consideration settleable in stock is calculated as if the contingently issuable shares were outstanding as of the beginning of the period.
	The following table sets forth the computation of basic and diluted net loss per share (in millions, except per share data):
		Three Months Ended							Nine Months Ended
		September 30,							September 30,
		2014				2013			2014			2013
	Numerator for basic and diluted net loss per share:
	Net loss for basic	$	(5.2	)		$	(6.0	)	$	(23.7	)	$	(27.2	)
	Impact of income related to mark-to-market on contingent consideration obligation settleable in shares	(0.9		)		—			(0.7		)	—
	Net loss for diluted	$	(6.1	)		$	(6.0	)	$	(24.4	)	$	(27.2	)
	Denominator for basic and diluted net loss per share:
	Weighted average common shares outstanding for basic	75.8				71.4			74.7			70.7
	Dilutive potential common stock outstanding:
	Contingently issuable shares related to contingent consideration obligation settleable in shares	0.3				—			0.3			—
	Weighted average common shares outstanding for diluted	76.1				71.4			75			70.7
	Basic net loss per share	$	(0.07	)		$	(0.08	)	$	(0.32	)	$	(0.38	)
	Diluted net loss per share	$	(0.08	)		$	(0.08	)	$	(0.33	)	$	(0.38	)
	Historical outstanding anti-dilutive securities not included in diluted net loss per share attributable to common stockholders calculation (in millions):
		Three Months Ended						Nine Months Ended
		September 30,						September 30,
		2014			2013			2014		2013
	Options outstanding to purchase common stock	3.8			6.6			3.8		6.6
	Unvested restricted stock units	4.3			3.7			4.3		3.7
	Total	8.1			10.3			8.1		10.3

Financial_Statement_Details

Financial Statement Details	9 Months Ended
	Sep. 30, 2014
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 with contractual maturities of less than one year were as follows:
		30-Sep-14
		Amortized			Gross			Gross			Estimated
		Cost			Unrealized			Unrealized			Market
					Gains			Losses			Value
	U.S. government agencies	$	8.8		$	—		$	—		$	8.8
	Corporate debt	2			—			—			2
	Commercial paper	0.9			—			—			0.9
	Total	$	11.7		$	—		$	—		$	11.7
		December 31, 2013
		Amortized			Gross			Gross			Estimated
		Cost			Unrealized			Unrealized			Market
					Gains			Losses			Value
	U.S. government agencies	$	8.9		$	—		$	—		$	8.9
	Corporate debt	2.5			—			—			2.5
	Total	$	11.4		$	—		$	—		$	11.4
	Inventory
		30-Sep-14			31-Dec-13
	Raw materials	$	6.2		$	4.8
	Work-in-process	1.2			0.3
	Finished goods	6.9			3.9
	Total	$	14.3		$	9
	Accounts Payable and Accrued Liabilities
		30-Sep-14			31-Dec-13
	Accounts payable trade	$	7.9		$	4.2
	Accrued tax, audit, and legal fees	1.5			1.2
	Clinical trials	0.5			0.3
	Accrued other including warranty	7.5			4.8
	Acquisition-related liabilities	3.5			3.6
	Total	$	20.9		$	14.1
	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 three and nine months ended September 30, 2014 and 2013 were as follows:
		Three Months Ended						Nine Months Ended
		September 30,						September 30,
		2014			2013			2014			2013
	Beginning balance	$	0.9		$	0.3		$	0.9		$	0.3
	Charges to costs and expenses	1.6			2.1			3.8			3.5
	Costs incurred	(1.3		)	(1.1		)	(3.5		)	(2.5		)
	Ending balance	$	1.2		$	1.3		$	1.2		$	1.3

Commitments_and_Contingencies

Commitments and Contingencies	9 Months Ended
	Sep. 30, 2014
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 is an interest-only financing that bears an interest rate equal to the prime rate plus 0.5% and requires repayment of principal at the maturity date of November 2015. Under the revolving line of credit, available funds, which were up to $15.0 million as of September 30, 2014 can be drawn at any time, and repaid funds can be redrawn. No amounts have been drawn against the revolving line of credit.
	Per the Loan Agreement, $7.0 million was advanced under the Term Loan at the funding date in November 2012 and up to $13.0 million in additional funds was available upon our request from June 1, 2013 to September 30, 2013 (the "Draw Period"). In August 2013, the Loan Agreement was amended to change the Draw Period for the additional funds under the Term Loan to January 1, 2014 through March 31, 2014, at which time the Draw Period 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 are being 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 September 30, 2014, the remaining unamortized issuance costs and fees totaled $0.4 million. Principal repayment obligations under the Loan Agreement as of September 30, 2014 were as follows (in millions):
	Fiscal Year Ending
	Remainder of 2014	$	0.6
	2015	2.3
	2016	2.3
	Total	$	5.2
	Leases
	In April 2006, we entered into an office lease agreement for facilities located in San Diego, California. In August 2010, we entered into a First Amendment to Office Lease (the “First Lease Amendment”) with respect to facilities in the buildings at 6340 Sequence Drive and 6310 Sequence Drive, each in San Diego, California, and in October 2014, we entered into a Second Amendment to Office Lease (the “Second Lease Amendment”), which added the building at 6290 Sequence Drive to our lease. The Second Lease Amendment is described in further detail in Note 6 “Subsequent Events”. 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. These facility leases have annual rental increases ranging from approximately 2.5% to 4.0%. The difference between the straight-line expense over the term of the lease and actual amounts paid are recorded as deferred rent. In September 2008, our subsidiary in Sweden entered into a three-year lease for a small shared office space, which was renewed for a three-year term and has a quarterly adjustment clause for rent to increase or decrease in proportion to changes in consumer prices. In July 2012, our subsidiary SweetSpot entered into a five-year lease for a small office space in a multi-tenant commercial building in Portland, Oregon. Rental obligations, excluding real estate taxes, operating costs, and tenant improvement allowances, under all lease agreements as of September 30, 2014 were as follows (in millions):
	Fiscal Year Ending
	Remainder of 2014	$	0.7
	2015	2.9
	2016	2.6
	Total	$	6.2
	Total rent expense for the three and nine months ended September 30, 2014 was $0.8 million and $2.3 million, respectively, compared to $0.7 million and $2.2 million, respectively, for the same periods of 2013.
	Litigation
	Commencing on August 11, 2005, Abbott Diabetes Care, Inc. (“Abbott”) instituted various patent infringement proceedings against us in the United States District Court for the District of Delaware. In these proceedings Abbott sought, among other things, a declaratory judgment that our continuous glucose monitoring systems infringe certain patents held by Abbott.
	On July 2, 2014, we entered into a Settlement and License Agreement (the “Abbott Settlement Agreement”) with Abbott (Abbott and us together, the “settlement parties” and each, a “settlement party”). The Abbott Settlement Agreement was entered into in full settlement of all pending patent infringement legal proceedings brought by Abbott against us. In accordance with the Abbott Settlement Agreement, on July 7, 2014, the parties filed a joint stipulation of dismissal of all pending legal proceedings, which was granted by the court on July 11, 2014.
	The Abbott Settlement Agreement does not obligate us to pay any royalties or any other form of financial compensation. The Abbott Settlement Agreement provides for a royalty-free, worldwide, non-exclusive, non-sublicensable cross-license of certain patents. We receive a limited license from Abbott to the patents that Abbott has alleged that we infringed (and other Abbott patents that claim priority to such patents). We grant to Abbott a limited license of certain patents with an actual filing date prior to January 1, 2005 (and other of our patents that claim priority to such patents). In addition, each settlement party agrees not to (1) sue the other settlement party for patent infringement based on certain of their respective continuous glucose monitoring products, and (2) challenge any patent or patent application held by the other settlement party, subject to certain limited exceptions, in each case, until March 31, 2021. The cross-license and mutual covenant not to sue granted to each settlement party do not apply to the type of sensor technology used by the other settlement party.
	In the event of a change of control, the settlement party that is not acquired in the change of control (the “Non-Acquired Party”) shall be paid a one-time continuation fee of $25.0 million. If the Non-Acquired Party is not paid the continuation fee within 30 days after the effective date of such change of control, then the license granted by, and all covenants of, the Non-Acquired Party shall expire 30 days after the effective date of the change of control, but the license granted by, and all covenants of, the settlement party that is acquired shall survive such expiration.
	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 glucose monitoring systems. As of September 30, 2014, we had purchase commitments with vendors totaling $26.9 million due within one year. There are no material purchase commitments due beyond one year.

Development_and_Other_Agreemen

Development and Other Agreements	9 Months Ended
	Sep. 30, 2014
Disclosure Development Agreements Additional Information [Abstract]	'
Development and Other Agreements	'
	Development and Other Agreements
	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”). 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”). Under the terms of the Collaboration Agreement we will receive a royalty of up to 6% of commercial sales of the product. The Collaboration Agreement provides Edwards with an exclusive license to certain of our intellectual property rights used in the In-Hospital Product (“Edwards License”). The Edwards License is limited to the critical care sector of the in-hospital market. Our development obligations under the Collaboration Agreement were completed in the fourth quarter of 2012.
	Each of the milestones related to the Collaboration Agreement is considered to be substantive under the terms of the Collaboration Agreement and, at the outset of the Collaboration Agreement, we were entitled to receive up to $12.0 million in milestones related to regulatory approvals and manufacturing readiness, subject to reductions based on the timing of the receipt of approvals. We currently do not expect to receive the full amount of such milestones due to regulatory and joint development delays. We did not recognize any consideration for milestones related to the Collaboration Agreement for the three and nine months ended September 30, 2014 and 2013.
	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 system with Tandem's t:slim insulin delivery system in the United States. 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. We received an initial payment of $1.0 million as a result of the execution of the Tandem Agreement. We received a $1.0 million milestone in July 2014 related to the regulatory submission by Tandem of their CGM enabled insulin pump. We are also entitled to receive up to an additional $1.0 million upon the achievement of a milestone related to regulatory approvals as set forth in the Tandem Agreement. Each of the milestones related to the Tandem Agreement is considered to be substantive. During the three and nine months ended September 30, 2014 we recorded $1.0 million and $1.2 million, respectively, in development grant and other revenue related to consideration previously received for development efforts and the $1.0 million milestone for regulatory submission. During the three and nine months ended September 30, 2013 we recorded $0.1 million and $0.4 million, respectively, in development grant and other revenue related to consideration previously received for development efforts.
	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 Gen 6 Sensor over the next 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 2013, $0.5 million of the Helmsley Grant was received and $0.5 million was earned. During the three months ended September 30, 2014 we did not receive or earn any of the Helmsley Grant funds. During the nine months ended September 30, 2014, $1.5 million of the Helmsley Grant was received and $1.5 million was earned.

Subsequent_Events

Subsequent Events	9 Months Ended
	Sep. 30, 2014
Subsequent Events [Abstract]	'
Subsequent Events	'
	Subsequent Events
	On October 1, 2014, we entered into a Second Amendment to Office Lease (the “Second Lease Amendment”) with Kilroy Realty, L.P. (the “Landlord”) with respect to facilities in the buildings at 6340 Sequence Drive, 6310 Sequence Drive, and 6290 Sequence Drive, each in San Diego, California (the “Buildings”).
	Under the Second Lease Amendment, we will continue to lease approximately 129,000 square feet in the current locations at 6340 Sequence Drive and 6310 Sequence Drive, and will lease an additional 45,000 square feet at 6290 Sequence Drive, for a total of approximately 174,000 square feet of space. We also retain the right and obligation to lease an additional 45,000 square feet in the 6290 Sequence Drive location (the “Additional Space”). The lease term extends through March 2022. Rent payable by us under the Second Lease Amendment will be as follows (in millions):
	Fiscal Year Ending	Amount (1)
	Remainder of 2014	$	0.7
	2015	2.9
	2016	3.5
	2017	4
	2018	5
	Thereafter	16.9
	Total	$	33
	-1	Assumes rent payment for the Additional Space commencing on March 1, 2017.
	In addition, under the Second Lease Amendment, we are obligated to pay a share of the real estate taxes and operating costs for the Buildings. The total obligation for rent under the life of the lease for the Buildings is $33.0 million, excluding real estate taxes and operating costs.
	Provided we are not in default under the Second Lease Amendment and the Second Lease Amendment is still in effect, we generally have the right to terminate the lease starting at the 55th month of the Second Lease Amendment, as well as to extend the lease 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.
	On November 3, 2014, we entered into the SweetSpot Settlement Agreement. Pursuant to the terms of the SweetSpot Settlement Agreement, we will issue 89,300 shares of our common stock (the “Settlement Shares”) to the SweetSpot Security-holders in exchange for the cancellation of the remaining Milestone Payments. The SweetSpot Settlement Agreement also obligates us to file a Registration Statement on Form S-3 to cover the resale of the Settlement Shares by the SweetSpot Security-holders. Pursuant to the terms of the SweetSpot Settlement Agreement, upon issuance of the Settlement Shares, we will have no further obligation to issue any additional shares of our Common Stock to the SweetSpot Security-holders under the Merger Agreement.

Organization_and_Summary_of_Si1

Organization and Summary of Significant Accounting Policies (Policies)	9 Months Ended
	Sep. 30, 2014
Disclosure Organization And Summary Of Significant Accounting Policies Additional Information [Abstract]	'
New Accounting Pronouncements, Policy [Policy Text Block]	'
	Recent Accounting Guidance
	In July 2013, the FASB issued authoritative guidance for Presentation of an Unrecognized Tax Benefit When a Net Operating Loss Carryforward, a Similar Tax Loss, or a Tax Credit Carryforward Exists, which provides explicit guidance on the financial statement presentation of an unrecognized tax benefit when a net operating loss carryforward, a similar tax loss, or a tax credit carryforward exists. The guidance is effective prospectively for fiscal years, and interim periods within those years, beginning after December 15, 2013, with early adoption permitted. We adopted this guidance on January 1, 2014, and the adoption of this guidance did not have a material impact on our consolidated financial statements or related financial statement disclosures.
	In May 2014, the 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 2017. 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.
Marketable Securities, Available-for-sale Securities, Policy [Policy Text Block]	'
	Short-Term Marketable Securities
	We have classified our short-term marketable securities as “available-for-sale” and carry them 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 do not 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 maturity.
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 $499.1 million at September 30, 2014. As of September 30, 2014, we had available cash, cash equivalents and short-term marketable securities totaling $74.9 million, excluding $1.0 million of restricted cash, and working capital of $82.8 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 related expenses or other operating expenses 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 September 30, 2015.
	We have prepared the accompanying unaudited consolidated financial statements in accordance with accounting principles generally accepted in the United States of America (“U.S. GAAP”) for interim financial information and with the instructions to Form 10-Q and Article 10 of Regulation S-X. Accordingly, they do not include all of the information and disclosures required by U.S. GAAP for complete financial statements. In the opinion of management, all adjustments, which include only normal recurring adjustments considered necessary for a fair presentation (except for the changes in estimates described below), have been included. Operating results for the three and nine months ended September 30, 2014 are not necessarily indicative of the results that may be expected for the year ending December 31, 2014. These unaudited consolidated financial statements should be read in conjunction with the audited financial statements and related notes thereto for the year ended December 31, 2013 included in the Annual Report on Form 10-K filed by us with the Securities and Exchange Commission on February 20, 2014.
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
	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 as, one operating segment.
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, employee bonus, clinical trial expenses, allowance for bad debt, accounting for the SweetSpot acquisition including contingent consideration, and share-based compensation expense.
Share-Based Compensation	'
	Share-Based Compensation
	We recorded $13.8 million and $35.7 million in share-based compensation expense during the three and nine months ended September 30, 2014, respectively, compared to $6.6 million and $18.0 million, respectively, during the three and nine months ended September 30, 2013. At September 30, 2014, unrecognized estimated compensation costs related to unvested stock options and restricted stock units totaled $116.6 million and are expected to be recognized through 2018. We issued performance restricted stock units (the “Performance Awards”) in connection with our acquisition of SweetSpot in March 2012. The performance targets for these Performance Awards are tied to earnings before interest, taxes, depreciation and amortization (“EBITDA”) for fiscal years 2013 and 2014. We recognize expense for the Performance Awards when it is probable that the EBITDA targets will be met. The performance target for fiscal 2013 EBITDA was not achieved. At September 30, 2014, we had $2.2 million of unrecognized share-based compensation expense related to the Performance Awards for the fiscal 2014 performance target. We use the grant date fair value of our common stock for valuing restricted stock unit awards. Our determination of the fair value of share-based payment awards on the date of grant is affected by our stock price. Compensation costs will be adjusted for future changes in estimated forfeitures.
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 and Latin America. 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, data management software and a USB cable. Disposable sensors for use with the durable system are sold separately in packages of four. 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 by reducing revenues and establishing a liability account at the time of shipment based on historical experience. Returns have historically been immaterial.
	We have entered into distribution agreements with Byram Healthcare and their subsidiaries ("Byram"), RGH Enterprises, Inc. (“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 (“Stocking Distributors”), whereby the 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 (“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 Freight on Board (“FOB”) shipping point (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.
	We have collaborative license and development arrangements with strategic partners for the development and commercialization of products utilizing our technologies. The terms of these agreements typically include the license of certain intellectual property rights and the provision of multiple deliverables by us (for example, research and development services, product prototypes and products for use in clinical trials) in exchange for consideration to us of some combination of non-refundable license fees, funding of research and development activities, payments based upon achievement of development milestones and royalties in the form of a designated percentage of product sales or profits. With the exception of royalties, these types of consideration are classified as development grant and other revenue in our consolidated statements of operations and are generally recognized over the service period except for substantive milestone payments, which are generally recognized when the milestone is achieved. In determining whether each milestone is substantive, we considered whether the consideration earned by achieving the milestone should (i) be commensurate with either (a) our performance to achieve the milestone or (b) the enhancement of value of the item delivered as a result of a specific outcome resulting from our performance to achieve the milestone, (ii) relate solely to past performance and (iii) be reasonable relative to all deliverables and payment terms in the arrangement. We recognize royalties in the period in which we obtain the royalty report, which is necessary to determine the amount of royalties we are entitled to receive.
	Non-refundable license fees are recognized as revenue when we have a contractual right to receive such payment, the contract price is fixed or determinable, the collection of the resulting receivable is reasonably assured and we have no further performance obligations under the license agreement. Multiple element arrangements, such as license, development and other multiple element service arrangements are analyzed to determine how the arrangement consideration should be allocated among the separate units of accounting, or whether they must be accounted for as a single unit of accounting.
	For transactions containing multiple element arrangements, we consider deliverables as separate units of accounting and recognize deliverables as revenue upon delivery only if (i) the deliverable has standalone value and (ii) if the arrangement includes a general right of return relative to the delivered item(s), delivery or performance of the undelivered item(s) is probable and substantially controlled by us. We allocate consideration to the separate units of accounting using the relative selling price method, in which allocation of consideration is based on vendor-specific objective evidence (“VSOE”) if available, third-party evidence (“TPE”), or if VSOE and TPE are not available, management’s best estimate of a standalone selling price for elements.
	We use judgment in estimating the value allocable to the deliverables in an agreement based on our estimate of the fair value or relative selling price attributable to the related deliverables and the consideration from such an agreement is typically recognized as product revenue or development grant and other revenue. For arrangements that are accounted for as a single unit of accounting, total payments under the arrangement are recognized as revenue on a straight-line basis over the period we expect to complete our performance obligations. We review the estimated period of our performance obligations on a periodic basis and update the recognition period as appropriate. The cumulative amount of revenue earned is limited to the cumulative amount of payments we are entitled to as of the period ending date.
	If we cannot reasonably estimate when our performance obligation either ceases or becomes inconsequential, then revenue is deferred until we can reasonably estimate when the performance obligation ceases or becomes inconsequential. Revenue is then recognized over the remaining estimated period of performance. Deferred revenue amounts are classified as current liabilities to the extent that revenue is expected to be recognized within one year.
	Significant management judgment is required in determining the level of effort required under an arrangement and the period over which we are expected to complete our performance obligations under an arrangement.
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.
Foreign Currency	'
	Foreign Currency
	The financial statements of our non-U.S. subsidiary, 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 income 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 other 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.
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 base the fair value of our Level 1 financial instruments that are in active markets using quoted market prices for identical instruments. Our Level 1 financial instruments include certificates of deposit.
	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.
	Certain contingent consideration liabilities are classified within Level 3 of the fair value hierarchy because they use unobservable inputs. For those liabilities, fair value is determined using a probability-weighted discounted cash flow model, the significant inputs, which include the probability and expected timing of achievement and the discount rate, are not observable in the market.
	The following table represents our fair value hierarchy for our financial assets (cash equivalents, marketable securities and restricted cash) and liabilities measured at fair value on a recurring basis as of September 30, 2014 (in millions):
		Fair Value Measurements Using
		Level 1			Level 2		Level 3			Total
	Cash equivalents	$	—		$	24.5	$	—		$	24.5
	Marketable securities, available for sale
	U.S. government agencies	—			8.8		—			8.8
	Corporate debt	—			2		—			2
	Commercial paper	—			0.9		—			0.9
	Total marketable securities, available for sale	$	—		$	11.7	$	—		$	11.7
	Restricted cash	$	1		$	—	$	—		$	1
	Contingent consideration liability	$	—		$	—	$	3.5		$	3.5
	The following table represents our fair value hierarchy for our financial assets (cash equivalents, marketable securities and restricted cash) and liabilities measured at fair value on a recurring basis as of December 31, 2013 (in millions):
		Fair Value Measurements Using
		Level 1			Level 2		Level 3			Total
	Cash equivalents	$	—		$	28.7	$	—		$	28.7
	Marketable securities, available for sale
	U.S. government agencies	—			8.9		—			8.9
	Corporate debt	—			2.5		—			2.5
	Total marketable securities, available for sale	$	—		$	11.4	$	—		$	11.4
	Restricted cash	$	1		$	—	$	—		$	1
	Contingent consideration liability	$	—		$	—	$	4.2		$	4.2
	Additional Disclosures Regarding Fair Value Measurements
	The book values of cash equivalents, short-term marketable securities, accounts receivable and accounts payable approximate their respective fair values due to the short-term nature of these instruments.
	Non-Financial Assets and Liabilities Measured at Fair Value on a Nonrecurring Basis
	Our non-financial assets and liabilities (e.g., goodwill, intangible assets, property and equipment and nonfinancial assets and liabilities initially measured at fair value in a business combination) are re-measured at fair value subsequent to initial recognition only when they are deemed to be other-than-temporarily impaired. There were no non-financial assets and liabilities deemed to be other-than-temporarily impaired and measured at fair value on a nonrecurring basis for the periods presented.
Contingent Consideration Liability	'
	Contingent Consideration Liability
	On February 21, 2012, we entered into an Agreement and Plan of Merger (the “Merger Agreement”) to acquire SweetSpot. The merger was consummated on March 6, 2012 (the “Closing”). In connection with the acquisition of SweetSpot, at the closing of the acquisition, we agreed to issue up to an additional 357,176 shares of our common stock to the security holders of SweetSpot (the “SweetSpot Security-holders”) upon the achievement of certain platform development milestones and regulatory approval milestones (the “Milestone Payments”), which are classified as contingent consideration. The fair value of the contingent consideration at the closing of $2.2 million was determined using a probability-weighted discounted cash flow model, the significant inputs of which are not observable in the market. The key assumptions in applying this approach are the interest rate and the estimated probabilities and timing assigned to the Milestone Payments being achieved. During 2012, approximately $1.1 million related to the contingent consideration was earned and paid through the issuance of 89,296 shares of our common stock. We did not issue any shares of common stock for Milestone Payments in 2013 or through September 30, 2014. On November 3, 2014, we entered into a Settlement Agreement with the stockholders’ agent for the SweetSpot Security-holders (the “SweetSpot Settlement Agreement), whereby we agreed to, among other things, issue 89,300 shares of our common stock in exchange for the cancellation of the remaining Milestone Payments. For details on the SweetSpot Settlement Agreement please see Note 6 "Subsequent Events."
	We reassess the fair value of our contingent consideration liability on a quarterly basis. Changes in fair value are recorded in the consolidated statements of operations as research and development expense since the milestones are related to development activities.
	The following table sets forth the change in the estimated fair value for our liabilities measured on a recurring basis using significant unobservable inputs (Level 3) (in millions):
		Three Months Ended					Nine Months Ended
		September 30,					September 30,
		2014			2013		2014			2013
	Fair value measurement at the beginning of period	$	4.4		$	2.7	$	4.2		$	1.7
	Changes in fair value measurement included in operating expenses	(0.9		)	1		(0.7		)	2
	Fair value measurement at end of period	$	3.5		$	3.7	$	3.5		$	3.7
	The changes in the fair value of the contingent consideration for the SweetSpot acquisition for the periods presented resulted from updates to assumed probability of achievement of milestones and adjustments to the discount periods.
Impairment of Goodwill and Intangible Assets	'
	Impairment of Goodwill and Intangible Assets
	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.
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.

Organization_and_Summary_of_Si2

Organization and Summary of Significant Accounting Policies (Tables)	9 Months Ended
	Sep. 30, 2014
Disclosure Organization And Summary Of Significant Accounting Policies Additional Information [Abstract]	'
Fair Value Hierarchy for Financial Assets	'
	The following table represents our fair value hierarchy for our financial assets (cash equivalents, marketable securities and restricted cash) and liabilities measured at fair value on a recurring basis as of September 30, 2014 (in millions):
		Fair Value Measurements Using
		Level 1			Level 2		Level 3			Total
	Cash equivalents	$	—		$	24.5	$	—		$	24.5
	Marketable securities, available for sale
	U.S. government agencies	—			8.8		—			8.8
	Corporate debt	—			2		—			2
	Commercial paper	—			0.9		—			0.9
	Total marketable securities, available for sale	$	—		$	11.7	$	—		$	11.7
	Restricted cash	$	1		$	—	$	—		$	1
	Contingent consideration liability	$	—		$	—	$	3.5		$	3.5
	The following table represents our fair value hierarchy for our financial assets (cash equivalents, marketable securities and restricted cash) and liabilities measured at fair value on a recurring basis as of December 31, 2013 (in millions):
		Fair Value Measurements Using
		Level 1			Level 2		Level 3			Total
	Cash equivalents	$	—		$	28.7	$	—		$	28.7
	Marketable securities, available for sale
	U.S. government agencies	—			8.9		—			8.9
	Corporate debt	—			2.5		—			2.5
	Total marketable securities, available for sale	$	—		$	11.4	$	—		$	11.4
	Restricted cash	$	1		$	—	$	—		$	1
	Contingent consideration liability	$	—		$	—	$	4.2		$	4.2
Change in Estimated Fair Value of Liabilities Measured on Recurring Basis	'
	The following table sets forth the change in the estimated fair value for our liabilities measured on a recurring basis using significant unobservable inputs (Level 3) (in millions):
		Three Months Ended					Nine Months Ended
		September 30,					September 30,
		2014			2013		2014			2013
	Fair value measurement at the beginning of period	$	4.4		$	2.7	$	4.2		$	1.7
	Changes in fair value measurement included in operating expenses	(0.9		)	1		(0.7		)	2
	Fair value measurement at end of period	$	3.5		$	3.7	$	3.5		$	3.7

Net_Loss_Per_Common_Share_Tabl

Net Loss Per Common Share (Tables)	9 Months Ended
	Sep. 30, 2014
Earnings Per Share [Abstract]	'
Schedule of Earnings Per Share, Basic and Diluted	'
	The following table sets forth the computation of basic and diluted net loss per share (in millions, except per share data):
		Three Months Ended							Nine Months Ended
		September 30,							September 30,
		2014				2013			2014			2013
	Numerator for basic and diluted net loss per share:
	Net loss for basic	$	(5.2	)		$	(6.0	)	$	(23.7	)	$	(27.2	)
	Impact of income related to mark-to-market on contingent consideration obligation settleable in shares	(0.9		)		—			(0.7		)	—
	Net loss for diluted	$	(6.1	)		$	(6.0	)	$	(24.4	)	$	(27.2	)
	Denominator for basic and diluted net loss per share:
	Weighted average common shares outstanding for basic	75.8				71.4			74.7			70.7
	Dilutive potential common stock outstanding:
	Contingently issuable shares related to contingent consideration obligation settleable in shares	0.3				—			0.3			—
	Weighted average common shares outstanding for diluted	76.1				71.4			75			70.7
	Basic net loss per share	$	(0.07	)		$	(0.08	)	$	(0.32	)	$	(0.38	)
	Diluted net loss per share	$	(0.08	)		$	(0.08	)	$	(0.33	)	$	(0.38	)
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):
		Three Months Ended						Nine Months Ended
		September 30,						September 30,
		2014			2013			2014		2013
	Options outstanding to purchase common stock	3.8			6.6			3.8		6.6
	Unvested restricted stock units	4.3			3.7			4.3		3.7
	Total	8.1			10.3			8.1		10.3

Financial_Statement_Details_Ta

Financial Statement Details (Tables)	9 Months Ended
	Sep. 30, 2014
Disclosure of Financial Statement Details [Abstract]	'
Short Term Marketable Securities, Available for Sale	'
	Short Term Marketable Securities, Available for Sale
	Short term marketable securities, consisting solely of debt securities with contractual maturities of less than one year were as follows:
		30-Sep-14
		Amortized			Gross			Gross			Estimated
		Cost			Unrealized			Unrealized			Market
					Gains			Losses			Value
	U.S. government agencies	$	8.8		$	—		$	—		$	8.8
	Corporate debt	2			—			—			2
	Commercial paper	0.9			—			—			0.9
	Total	$	11.7		$	—		$	—		$	11.7
		December 31, 2013
		Amortized			Gross			Gross			Estimated
		Cost			Unrealized			Unrealized			Market
					Gains			Losses			Value
	U.S. government agencies	$	8.9		$	—		$	—		$	8.9
	Corporate debt	2.5			—			—			2.5
	Total	$	11.4		$	—		$	—		$	11.4
Inventory	'
	Inventory
		30-Sep-14			31-Dec-13
	Raw materials	$	6.2		$	4.8
	Work-in-process	1.2			0.3
	Finished goods	6.9			3.9
	Total	$	14.3		$	9
Accounts Payable and Accrued Liabilities	'
	Accounts Payable and Accrued Liabilities
		30-Sep-14			31-Dec-13
	Accounts payable trade	$	7.9		$	4.2
	Accrued tax, audit, and legal fees	1.5			1.2
	Clinical trials	0.5			0.3
	Accrued other including warranty	7.5			4.8
	Acquisition-related liabilities	3.5			3.6
	Total	$	20.9		$	14.1
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 three and nine months ended September 30, 2014 and 2013 were as follows:
		Three Months Ended						Nine Months Ended
		September 30,						September 30,
		2014			2013			2014			2013
	Beginning balance	$	0.9		$	0.3		$	0.9		$	0.3
	Charges to costs and expenses	1.6			2.1			3.8			3.5
	Costs incurred	(1.3		)	(1.1		)	(3.5		)	(2.5		)
	Ending balance	$	1.2		$	1.3		$	1.2		$	1.3

Commitments_and_Contingencies_

Commitments and Contingencies (Tables)	9 Months Ended
	Sep. 30, 2014
Commitments and Contingencies Disclosure [Abstract]	'
Schedule of Maturities of Long-term Debt [Table Text Block]	'
	Principal repayment obligations under the Loan Agreement as of September 30, 2014 were as follows (in millions):
	Fiscal Year Ending
	Remainder of 2014	$	0.6
	2015	2.3
	2016	2.3
	Total	$	5.2
Rental Obligations	'
	Rental obligations, excluding real estate taxes, operating costs, and tenant improvement allowances, under all lease agreements as of September 30, 2014 were as follows (in millions):
	Fiscal Year Ending
	Remainder of 2014	$	0.7
	2015	2.9
	2016	2.6
	Total	$	6.2
	Rent payable by us under the Second Lease Amendment will be as follows (in millions):
	Fiscal Year Ending	Amount (1)
	Remainder of 2014	$	0.7
	2015	2.9
	2016	3.5
	2017	4
	2018	5
	Thereafter	16.9
	Total	$	33
	-1	Assumes rent payment for the Additional Space commencing on March 1, 2017.

Subsequent_Events_Lease_Commit

Subsequent Events Lease Commitments (Tables)	9 Months Ended
	Sep. 30, 2014
Subsequent Event [Line Items]	'
Rental Obligations	'
	Rental obligations, excluding real estate taxes, operating costs, and tenant improvement allowances, under all lease agreements as of September 30, 2014 were as follows (in millions):
	Fiscal Year Ending
	Remainder of 2014	$	0.7
	2015	2.9
	2016	2.6
	Total	$	6.2
	Rent payable by us under the Second Lease Amendment will be as follows (in millions):
	Fiscal Year Ending	Amount (1)
	Remainder of 2014	$	0.7
	2015	2.9
	2016	3.5
	2017	4
	2018	5
	Thereafter	16.9
	Total	$	33
	-1	Assumes rent payment for the Additional Space commencing on March 1, 2017.

Organization_and_Summary_of_Si3

Organization and Summary of Significant Accounting Policies - Additional Information (Detail) (USD $)	1 Months Ended	3 Months Ended		9 Months Ended		12 Months Ended
In Millions, except Share data, unless otherwise specified	Mar. 06, 2012	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013	Dec. 31, 2012	Dec. 31, 2013
Organization And Summary Of Significant Accounting Policies [Line Items]	'	'	'	'	'	'	'
Accumulated deficit	'	$499.10	'	$499.10	'	'	$475.40
Cash, cash equivalents and short-term investments	'	74.9	'	74.9	'	'	'
Restricted cash	'	1	'	1	'	'	1
Working capital	'	82.8	'	82.8	'	'	'
Allocated share-based compensation expense	'	13.8	6.6	35.7	18	'	'
Unrecognized compensation cost	'	116.6	'	116.6	'	'	'
Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized, Share-based Awards Other than Options	'	2.2	'	2.2	'	'	'
Money back guarantee period (days)	'	'	'	'30 days	'	'	'
Business Combination, Contingent Consideration, Liability Shares	357,176	'	'	'	'	'	'
Fair value of contingent consideration	2.2	'	'	'	'	'	'
Business acquisition, Contingent consideration earned	'	'	'	'	'	$1.10	'
Business acquisition, shares issued	'	'	'	'	'	89,296	'
Business acquisition, shares issuable up on achievement of milestones	'	89,300	'	89,300	'	'	'
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	'	'	'

Organization_and_Summary_of_Si4

Organization and Summary of Significant Accounting Policies - Fair Value Hierarchy for Financial Assets (Detail) (USD $)	Sep. 30, 2014	Dec. 31, 2013
In Millions, unless otherwise specified
Organization And Summary Of Significant Accounting Policies [Line Items]	'	'
Cash Equivalents, at Carrying Value	$24.50	$28.70
Marketable securities, available for sale	11.7	11.4
Restricted cash	1	1
Contingent consideration	3.5	4.2
U.S. government agencies [Member]	'	'
Organization And Summary Of Significant Accounting Policies [Line Items]	'	'
Marketable securities, available for sale	8.8	8.9
Commercial paper [Member]	'	'
Organization And Summary Of Significant Accounting Policies [Line Items]	'	'
Marketable securities, available for sale	0.9	'
Corporate debt [Member]	'	'
Organization And Summary Of Significant Accounting Policies [Line Items]	'	'
Marketable securities, available for sale	2	2.5
Level 1 [Member]	'	'
Organization And Summary Of Significant Accounting Policies [Line Items]	'	'
Cash Equivalents, at Carrying Value	0	0
Marketable securities, available for sale	0	0
Restricted cash	1	1
Contingent consideration	0	0
Level 1 [Member] | U.S. government agencies [Member]	'	'
Organization And Summary Of Significant Accounting Policies [Line Items]	'	'
Marketable securities, available for sale	0	0
Level 1 [Member] | Commercial paper [Member]	'	'
Organization And Summary Of Significant Accounting Policies [Line Items]	'	'
Marketable securities, available for sale	0	'
Level 1 [Member] | Corporate debt [Member]	'	'
Organization And Summary Of Significant Accounting Policies [Line Items]	'	'
Marketable securities, available for sale	0	0
Level 2 [Member]	'	'
Organization And Summary Of Significant Accounting Policies [Line Items]	'	'
Cash Equivalents, at Carrying Value	24.5	28.7
Marketable securities, available for sale	11.7	11.4
Restricted cash	0	0
Contingent consideration	0	0
Level 2 [Member] | U.S. government agencies [Member]	'	'
Organization And Summary Of Significant Accounting Policies [Line Items]	'	'
Marketable securities, available for sale	8.8	8.9
Level 2 [Member] | Commercial paper [Member]	'	'
Organization And Summary Of Significant Accounting Policies [Line Items]	'	'
Marketable securities, available for sale	0.9	'
Level 2 [Member] | Corporate debt [Member]	'	'
Organization And Summary Of Significant Accounting Policies [Line Items]	'	'
Marketable securities, available for sale	2	2.5
Level 3 [Member]	'	'
Organization And Summary Of Significant Accounting Policies [Line Items]	'	'
Cash Equivalents, at Carrying Value	0	0
Marketable securities, available for sale	0	0
Restricted cash	0	0
Contingent consideration	3.5	4.2
Level 3 [Member] | U.S. government agencies [Member]	'	'
Organization And Summary Of Significant Accounting Policies [Line Items]	'	'
Marketable securities, available for sale	0	0
Level 3 [Member] | Commercial paper [Member]	'	'
Organization And Summary Of Significant Accounting Policies [Line Items]	'	'
Marketable securities, available for sale	0	'
Level 3 [Member] | Corporate debt [Member]	'	'
Organization And Summary Of Significant Accounting Policies [Line Items]	'	'
Marketable securities, available for sale	$0	$0

Organization_and_Summary_of_Si5

Organization and Summary of Significant Accounting Policies - Changes in Estimated Fair Value of Liabilities (Detail) (USD $)	3 Months Ended		9 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]	'	'	'	'
Fair value measurement at the beginning of period	$4.40	$2.70	$4.20	$1.70
Changes in fair value measurement included in operating expenses	-0.9	1	-0.7	2
Fair value measurement at end of period	$3.50	$3.70	$3.50	$3.70

Net_Loss_Per_Common_Share_Net_

Net Loss Per Common Share Net Loss per Common Share - Basic and Diluted Net Loss per Share (Details) (USD $)	3 Months Ended		9 Months Ended
In Millions, except Per Share data, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Numerator for basic and diluted net loss per share:	'	'	'	'
Net loss for basic	($5.20)	($6)	($23.70)	($27.20)
Impact of income related to mark-to-market on contingent consideration obligation settleable in shares	-0.9	0	-0.7	0
Net loss for diluted	($6.10)	($6)	($24.40)	($27.20)
Denominator for basic and diluted net loss per share:	'	'	'	'
Weighted average common shares outstanding for basic	75.8	71.4	74.7	70.7
Dilutive potential common stock outstanding:	'	'	'	'
Contingently issuable shares related to contingent consideration obligation settleable in shares	0.3	0	0.3	0
Weighted average common shares outstanding for diluted	76.1	71.4	75	70.7
Basic net loss per share	($0.07)	($0.08)	($0.32)	($0.38)
Diluted net loss per share	($0.08)	($0.08)	($0.33)	($0.38)

Net_Loss_Per_Common_Share_Hist

Net Loss Per Common Share - Historical Outstanding Anti-Dilutive Securities (Detail)	3 Months Ended		9 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]	'	'	'	'
Outstanding anti-dilutive securities	8.1	10.3	8.1	10.3
Options outstanding to purchase common stock	'	'	'	'
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]	'	'	'	'
Outstanding anti-dilutive securities	3.8	6.6	3.8	6.6
Unvested restricted stock units	'	'	'	'
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]	'	'	'	'
Outstanding anti-dilutive securities	4.3	3.7	4.3	3.7

Financial_Statement_Details_Sh

Financial Statement Details - Short Term Marketable Securities, Available for Sale (Detail) (USD $)	9 Months Ended	12 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013
Financial Statement Details [Line Items]	'	'
Amortized Cost	$11.70	$11.40
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Estimated Market Value	11.7	11.4
U.S. government agencies [Member]	'	'
Financial Statement Details [Line Items]	'	'
Amortized Cost	8.8	8.9
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Estimated Market Value	8.8	8.9
Commercial paper [Member]	'	'
Financial Statement Details [Line Items]	'	'
Amortized Cost	0.9	'
Gross Unrealized Gains	0	'
Gross Unrealized Losses	0	'
Estimated Market Value	0.9	'
Corporate debt [Member]	'	'
Financial Statement Details [Line Items]	'	'
Amortized Cost	2	2.5
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Estimated Market Value	$2	$2.50

Financial_Statement_Details_In

Financial Statement Details - Inventory (Detail) (USD $)	Sep. 30, 2014	Dec. 31, 2013
In Millions, unless otherwise specified
Disclosure of Financial Statement Details [Abstract]	'	'
Raw materials	$6.20	$4.80
Work-in-process	1.2	0.3
Finished goods	6.9	3.9
Total	$14.30	$9

Financial_Statement_Details_Ac

Financial Statement Details - Accounts Payable and Accrued Liabilities (Detail) (USD $)	Sep. 30, 2014	Dec. 31, 2013
In Millions, unless otherwise specified
Disclosure of Financial Statement Details [Abstract]	'	'
Accounts payable trade	$7.90	$4.20
Accrued tax, audit, and legal fees	1.5	1.2
Clinical trials	0.5	0.3
Accrued other including warranty	7.5	4.8
Acquisition-related liabilities	3.5	3.6
Total	$20.90	$14.10

Financial_Statement_Details_Ac1

Financial Statement Details - Accrued Warranty (Detail) (USD $)	3 Months Ended		9 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Movement in Standard Product Warranty Accrual [Roll Forward]	'	'	'	'
Beginning balance	$0.90	$0.30	$0.90	$0.30
Charges to costs and expenses	1.6	2.1	3.8	3.5
Product Warranty Accrual, Payments	-1.3	-1.1	-3.5	-2.5
Ending balance	$1.20	$1.30	$1.20	$1.30

Commitments_and_Contingencies_1

Commitments and Contingencies - Additional Information (Detail) (USD $)	1 Months Ended	3 Months Ended		9 Months Ended		12 Months Ended
In Millions, unless otherwise specified	Nov. 30, 2012	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013	Dec. 31, 2012
Schedule Of Commitments And Contingencies [Line Items]	'	'	'	'	'	'
Long-term Line of Credit	$15	'	'	'	'	'
Term Loan Debt	20	'	'	'	'	'
Prime Rate Plus	0.50%	'	'	'	'	'
Term Loan Advances Aggregate Amount	7	'	'	'	'	'
Debt Instrument, Unused Borrowing Capacity, Amount	13	15	'	15	'	'
Debt Instrument Basis Spread On Treasury Variable Rate	6.94%	'	'	'	'	'
Debt Instrument, Maturity Date	1-Nov-16	'	'	'	'	'
Debt Issuance Cost	'	'	'	'	'	1.1
Unamortized Debt Issuance Expense	'	0.4	'	0.4	'	'
Option to renew lease, in years	'	'	'	'5 years	'	'
Potential rental rate adjustment, minimum	'	'	'	2.50%	'	'
Potential rental rate adjustment, maximum	'	'	'	4.00%	'	'
Term of lease (years)	'	'	'	'3 years	'	'
Rent expense	'	0.8	0.7	2.3	2.2	'
Purchase commitments with vendors total	'	26.9	'	26.9	'	'
Purchase commitments with vendors total maximum term, in years	'	'	'	'1 year	'	'
Remainder of 2014	'	0.6	'	0.6	'	'
2015	'	2.3	'	2.3	'	'
2016	'	2.3	'	2.3	'	'
Total	'	$5.20	'	$5.20	'	'
Subsidiaries [Member]	'	'	'	'	'	'
Schedule Of Commitments And Contingencies [Line Items]	'	'	'	'	'	'
Term of lease (years)	'	'	'	'5 years	'	'

Commitments_and_Contingencies_2

Commitments and Contingencies - Rental Obligations (Detail) (USD $)	Sep. 30, 2014
In Millions, unless otherwise specified
Commitments and Contingencies Disclosure [Abstract]	'
Remainder of 2014	$0.70
2015	2.9
2016	2.6
Total	$6.20

Commitments_and_Contingencies_3

Commitments and Contingencies Commitments and Contingencies - Litigation (Details) (USD $)	9 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2014
Commitments and Contingencies Disclosure [Abstract]	'
Cross-licensing continuation fee upon change of control	$25
Number of days a cross-licensing continuation fee is due upon change of control	'30 days
Number of days the cross-license expires upon change of control when cross-licensing continuation fee is not paid	'30 days

Development_and_Other_Agreemen1

Development and Other Agreements - Additional Information (Detail) (USD $)

3 Months Ended

9 Months Ended

12 Months Ended

9 Months Ended

12 Months Ended

1 Months Ended

1 Months Ended

9 Months Ended

3 Months Ended

9 Months Ended

1 Months Ended

9 Months Ended

In Millions, unless otherwise specified

Sep. 30, 2014

Sep. 30, 2013

Sep. 30, 2014

Sep. 30, 2013

Dec. 31, 2013

Jul. 31, 2013

Sep. 30, 2014

Dec. 31, 2013

Jul. 31, 2013

Jul. 31, 2013

Jul. 31, 2013

Nov. 30, 2008

Sep. 30, 2014

Sep. 30, 2014

Sep. 30, 2013

Sep. 30, 2014

Sep. 30, 2013

Feb. 01, 2012

Feb. 29, 2012

Jul. 31, 2014

Sep. 30, 2014

Helmsley Grant [Member]

Helmsley Grant [Member]

Option One [Member]

Option Two [Member]

Option One [Member]

Edwards Lifesciences LLC [Member]

Edwards Lifesciences LLC [Member]

Tandem Diabetes Care, Inc. [Member]

Tandem Diabetes Care, Inc. [Member]

Tandem Diabetes Care, Inc. [Member]

Tandem Diabetes Care, Inc. [Member]

Tandem Diabetes Care, Inc. [Member]

Tandem Diabetes Care, Inc. [Member]

Regulatory Submission Milestone [Member]

Regulatory Approval Milestone [Member] [Member]

Research and Development Grant [Member]

Research and Development Grant [Member]

Maximum [Member]

Initial Payment [Member]

Tandem Diabetes Care, Inc. [Member]

Tandem Diabetes Care, Inc. [Member]

Development Agreements [Line Items]

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Third party contribution to off set expenses

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

$1

'

'

'

Commercial sales royalty maximum

'

'

'

'

'

'

'

'

'

'

'

'

6.00%

'

'

'

'

'

'

'

'

Development grant and other revenue

1.1

0.4

2.1

2.5

'

'

'

'

'

'

'

'

'

1

0.1

1.2

0.4

'

'

'

'

Money eligible to be received related to regulatory approvals and manufacturing readiness

'

'

'

'

'

'

'

'

'

'

'

12

'

'

'

'

'

'

'

'

'

One-time milestone payment, received

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

1

'

'

Additional milestone payments

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

1

1

Research and Development Arrangement, Value of Grant

'

'

'

'

'

4

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Research and Development Arrangement, Grants Received During Period

'

'

1.5

'

0.5

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

'

Royalty Guarantees, Commitments, Amounts, Per Year

'

'

'

'

'

'

'

'

'

'

2

'

'

'

'

'

'

'

'

'

'

Royalty Guarantees, Commitments, Commitment Period

'

'

'

'

'

'

'

'

'4 years

'

'

'

'

'

'

'

'

'

'

'

'

Royalty Guarantees, Commitments, Amount

'

'

'

'

'

'

'

'

'

6

'

'

'

'

'

'

'

'

'

'

'

Research and Development Arrangement, Contract to Perform for Others, Compensation Earned

'

'

'

'

'

'

$1.50

$0.50

'

'

'

'

'

'

'

'

'

'

'

'

'

Subsequent_Events_Details

Subsequent Events (Details) (USD $)	9 Months Ended	0 Months Ended
In Millions, except Share data, unless otherwise specified	Sep. 30, 2014	Nov. 04, 2014	Oct. 02, 2014	Oct. 01, 2014	Oct. 01, 2014	Oct. 01, 2014	Oct. 01, 2014	Oct. 01, 2014
		Subsequent Event	Subsequent Event	Subsequent Event	Property Subject to Operating Lease [Member]	Leased Building, 6290 Sequence Drive [Member]	Additional Available Space, 6290 Sequence Drive [Member]	Leased Buildings -6340 Sequence Drive and 6310 Sequence Drive [Member]
					Subsequent Event	Subsequent Event	Subsequent Event	Subsequent Event
					sqft	sqft	sqft	sqft
Subsequent Event [Line Items]	'	'	'	'	'	'	'	'
Leased Square Footage	'	'	'	'	174,000	45,000	45,000	129,000
Remainder of 2014	$0.70	'	'	$0.70	'	'	'	'
2015	2.9	'	'	2.9	'	'	'	'
2016	2.6	'	'	3.5	'	'	'	'
2017	'	'	'	4	'	'	'	'
2018	'	'	'	5	'	'	'	'
Future Lease Payments, Thereafter	'	'	'	16.9	'	'	'	'
Total	$6.20	'	'	$33	'	'	'	'
Lessee Leasing Arrangements, Operating Leases, Number of Renewal Term	'	'	2	'	'	'	'	'
Option to renew lease, in years	'5 years	'	'5 years	'	'	'	'	'
Business Acquisition Contingent Consideration Settlement Shares Issued	'	89,300	'	'	'	'	'	'
Business acquisition, shares issuable up on achievement of milestones	89,300	'	'	'	'	'	'	'