CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012
Cash flows from operating activities
Net income (loss)	$ (73,789)	$ 47,474
Adjustments to reconcile net income (loss) to net cash used in operating activities:
Depreciation and amortization	3,890	3,572
Stock-based compensation	13,257	12,214
Gain on marketable securities	(3)	(2)
Change in capped-call option valuation	1,422
Changes in operating assets and liabilities:
Receivables from collaborative arrangements	(1,169)	129
Prepaid expenses and other current assets	357	127
Inventories	(2,533)	(4,299)
Accounts payable	1,026	(81)
Accrued personnel-related expenses, accrued clinical and development expenses, and other accrued liabilities	2,941	(5,956)
Accrued interest on convertible subordinated notes	2,540
Deferred rent	(376)	(344)
Deferred revenue	4,120	(128,530)
Net cash used in operating activities	(48,317)	(75,696)
Cash flows from investing activities
Purchases of property and equipment	(1,431)	(1,762)
Purchases of available-for-sale securities	(211,797)	(185,456)
Maturities of available-for-sale securities	106,983	153,921
Sales of available-for-sale securities	17,600	8,520
Intangible asset	(30,000)
Release of restricted cash		60
Payments received on notes receivable	100
Net cash used in investing activities	(118,545)	(24,717)
Cash flows from financing activities
Payments on note payable and capital lease		(69)
Proceeds from issuances of common stock, net	26,433	216,800
Payment for capped calls	(36,800)
Proceeds from issuances of convertible subordinated notes, net	281,623
Net cash provided by financing activities	271,256	216,731
Net increase in cash and cash equivalents	104,394	116,318
Cash and cash equivalents at beginning of period	94,849	44,778
Cash and cash equivalents at end of period	$ 199,243	$ 161,096