CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Cash flows from operating activities
Net loss	$ (67,703)	$ (37,360)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	3,400	1,898
Stock-based compensation	13,535	6,095
Change in fair value of capped-call derivative assets	0	1,422
Other non-cash items	(2)	(1)
Changes in operating assets and liabilities:
Accounts receivable	(178)	0
Receivables from collaborative arrangements	2,316	(1,153)
Prepaid expenses and other current assets	(2,132)	(1,224)
Inventories	(430)	(2,481)
Other assets	(998)	0
Accounts payable	(1,174)	(221)
Accrued personnel-related expenses, accrued clinical and development expenses, and other accrued liabilities	4,448	(3,176)
Accrued interest on convertible subordinated notes	(1,527)	(174)
Deferred rent expense	116	(202)
Deferred revenue	(308)	4,946
Net cash used in operating activities	(50,637)	(31,631)
Cash flows from investing activities
Purchases of property and equipment	(1,620)	(740)
Purchases of available-for-sale securities	(56,649)	(104,125)
Maturities of available-for-sale securities	122,399	54,753
Sales of available-for-sale securities	5,000	5,000
Increase in intangible assets	(55,000)	0
Payments received on notes receivable	0	100
Net cash provided by (used in) investing activities	14,130	(45,012)
Cash flows from financing activities
Proceeds from issuances of common stock, net	18,272	2,991
Purchase of capped-call options	0	(36,800)
Proceeds from issuances of convertible subordinated notes, net of debt issuance costs	0	281,673
Net cash provided by financing activities	18,272	247,864
Net increase (decrease) in cash and cash equivalents	(18,235)	171,221
Cash and cash equivalents at beginning of period	143,510	94,849
Cash and cash equivalents at end of period	$ 125,275	$ 266,070