Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015
Cash flows from operating activities
Net loss	$ (121,084)	$ (79,753)
Adjustments to reconcile net loss to net cash used in operating activities:
Stock-based compensation	25,838	22,027
Amortization of premiums and accretion of discounts on investment securities, available for sale	(223)	(1,115)
Amortization of intangible assets	246
Depreciation	342	402
Loss on disposal of assets	5
Changes in operating assets and liabilities:
Accounts receivable, net	(293)
Interest and other receivables	298	(544)
Inventory	(2,512)
Prepaid expenses and other current assets	(4,623)	60
Restricted cash	(2,000)
Other assets	(782)	(46)
Accounts payable	(648)	900
Accrued liabilities	7,001	2,644
Deferred revenue	513
Long-term liabilities	(35)	205
Net cash used in operating activities	(97,957)	(55,220)
Cash flows from investing activities
Purchases of investment securities	(326,629)	(125,255)
Maturities of investment securities	159,260	209,454
Intangible assets	(8,000)
Purchases of property and equipment	(787)	(1,662)
Net cash (used in) provided by investing activities	(176,156)	82,537
Cash flows from financing activities
Proceeds from issuance of common stock, net of issuance costs	289,429	4,038
Proceeds from settlement agreement	14,320
Net cash provided by financing activities	303,749	4,038
Effect of exchange rate changes on cash		3
Net increase in cash and cash equivalents	29,636	31,358
Cash and cash equivalents
Beginning of period	102,138	61,854
End of period	131,774	$ 93,212
Supplemental disclosure of noncash information:
Property and equipment purchases in accounts payable and accrued liabilities	254
Stock-based compensation capitalized in inventory	$ 355