Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	3 Months Ended
Mar. 31, 2015	Mar. 31, 2014
Cash flows from operating activities:
Net loss	$ (35,801)	$ (16,107)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization of fixed assets	1,587	656
Stock-based compensation	3,620us-gaap_ShareBasedCompensation	1,995us-gaap_ShareBasedCompensation
Amortization of deferred license fees		(294)
Amortization of other long-term liabilities	(58)
Amortization of premium on short-term investments	377	145
Changes in assets and liabilities:
Prepaid expenses and other current assets	(364)	(643)
Accounts receivable	(205)
Inventory, net	(1,406)us-gaap_IncreaseDecreaseInInventories
Accounts payable	(646)	570
Accrued liabilities	(1,473)	1,456
Lease incentive obligation	(138)	(135)
Accrued interest	6	6
Net cash used in operating activities	(34,501)	(12,351)
Cash flows from investing activities:
Purchases of marketable securities	(11,145)	(2,352)
Maturities of marketable securities	31,116	24,419
Purchases of property and equipment	(3,207)	(4,763)
Net cash provided by investing activities	16,764	17,304
Cash flows from financing activities:
Proceeds from exercise of common stock options	386	88
Payments on capital lease obligations	(91)	(86)
Net cash provided by financing activities	295	2
Foreign currency exchange loss	(10)
Net increase (decrease) in cash and cash equivalents	(17,452)	4,955
Cash and cash equivalents, beginning of period	58,131	12,851
Cash and cash equivalents, end of period	40,679	17,806
Supplemental disclosure of non-cash investing and financing activities:
Unrealized gain (loss) on available-for-sale investments	195	8
Issuance of 21,826 and 32,666 shares of common stock to fund the Company’s 401(k) matching contribution for 2014 and 2013, respectively	$ 835	$ 456

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Amount of amortization of purchase premium on nonoperating securities.

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The increase (decrease) in cash associated with the entity's continuing operating, investing, and financing activities. While for technical reasons this element has no balance attribute, the default assumption is a debit balance consistent with its label.

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Amount of cash inflow (outflow) of financing activities, excluding discontinued operations. Financing activity cash flows include obtaining resources from owners and providing them with a return on, and a return of, their investment; borrowing money and repaying amounts borrowed, or settling the obligation; and obtaining and paying for other resources obtained from creditors on long-term credit.

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Amount of cash inflow (outflow) of investing activities, excluding discontinued operations. Investing activity cash flows include making and collecting loans and acquiring and disposing of debt or equity instruments and property, plant, and equipment and other productive assets.

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Net income after adjustments for dividends on preferred stock (declared in the period) and/or cumulative preferred stock (accumulated for the period).

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Amount of tax expense (benefit), before reclassification adjustments of gain (loss) on foreign currency translation adjustments, foreign currency transactions designated and effective as economic hedges of a net investment in a foreign entity and intra-entity foreign currency transactions that are of a long-term-investment nature.

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The total cash inflow associated with the amount received from holders to acquire the entity's shares under incentive and share awards, including stock option exercises. This item inherently excludes any excess tax benefit, which the entity may have realized and reported separately.

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