CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Cash flows from operating activities:
Net loss	$ (274,158)	$ (220,872)	$ (123,603)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation, amortization and impairment charges	4,136	8,307	4,614
Stock-based compensation	35,421	20,341	7,675
Deferred executive compensation expense	963	2,810	1,719
Revaluation of warrant liability		15,924	46,715
Increase (decrease) from:
Accounts receivable	(1,305)
Inventory	(413)
Other current assets	(2,113)	(4,714)	228
Other assets	(2,714)
Accounts payable	2,478	2,664	2,394
Accrued compensation and benefits	913	10,656	82
Accrued product development expenses	2,679	2,113	3,759
Other accrued expenses	1,340	4,669	1,271
Other liabilities	14,834	5,714	1,660
Deferred revenue	10	(230)	999
Deferred executive compensation paid	(3,953)	(1,063)	(775)
Net cash used in operating activities	(221,882)	(153,681)	(53,262)
Cash flows from investing activities:
Acquisitions of marketable securities		(89,554)
Proceeds from maturities of marketable securities	45,000	44,500
Change in restricted cash	(10,319)	(289)
Investment in property and equipment	(8,543)	(4,424)	(1,452)
Investment in intangible assets		(633)	(671)
Net cash provided by (used in) investing activities	26,138	(50,400)	(2,123)
Cash flows from financing activities:
Proceeds from long-term borrowings			4,375
Repayment of long-term borrowings	(2,100)	(1,400)	(1,400)
Principal payments under capital lease obligations	(15)	(54)	(66)
Proceeds from issuance of common stock, net of issuance costs	310,037		243,058
Reimbursements of amounts related to facility lease obligation	2,741
Proceeds from issuance of common stock pursuant to warrants		12,483	8,080
Proceeds from issuance of common stock pursuant to stock option and purchase plans	6,284	10,511	4,791
Payment of tax withholding obligations related to stock compensation	(3,363)	(4,336)	(827)
Net cash provided by financing activities	313,584	17,204	258,011
Effect of exchange rates on cash	(40)
Net increase (decrease) in cash and cash equivalents	117,800	(186,877)	202,626
Cash and cash equivalents, beginning of year	119,379	306,256	103,630
Cash and cash equivalents, end of year	237,179	119,379	306,256
Supplemental disclosures:
Interest paid	153	206	230
Income taxes paid	17
Capitalization of construction-in-progress related to facility lease obligation	96,671
Non-cash transaction - property and equipment included in accounts payable or accruals	$ 738	$ 579	$ 911