CONDENSED CONSOLIDATED BALANCE SHEETS (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Current assets:
Cash and cash equivalents	$ 436,520	$ 153,244
Marketable securities, current	294,157	331,192
Accounts receivable, net	132,637	79,117
Receivable from collaboration partners	90,951	68,209
Inventory	23,687	14,563
Deferred tax asset	3,416	3,416
Prepaid expenses and other current assets	33,729	38,215
Total current assets	1,015,097	687,956
Marketable securities, non-current	8,178	8,323
Property and equipment, net	30,034	25,933
Finite - lived intangible assets, net	252,749	257,969
Intangible assets - in-process research and development	171,500	171,500
Goodwill	193,675	193,675
Other assets	6,085	6,215
Total assets	1,677,318	1,351,571
Current liabilities:
Accounts payable	2,724	275
Accrued liabilities	36,788	48,252
Accrued clinical trials and related expenses	40,999	39,684
Accrued compensation	20,036	29,575
Deferred revenue	9,322	9,811
Other current liabilities	3,269	3,772
Total current liabilities	113,138	131,369
Convertible senior notes due 2016	177,503	174,404
Liability for contingent consideration, non-current	152,093	149,163
Deferred tax liability	51,940	51,940
Other liabilities	23,985	24,576
Commitments and contingencies (Note 11)
Stockholders' equity:
Preferred stock, $0.001 par value; 5,000,000 shares authorized; none issued and outstanding
Common stock, $0.001 par value; 200,000,000 shares authorized; 72,354,008 and 67,479,518 shares issued and outstanding as of March 31, 2013 and December 31, 2012, respectively	72	67
Additional paid-in capital	1,845,652	1,471,585
Receivable from stock option exercises	(2,363)	(534)
Accumulated other comprehensive income (loss)	42	74
Accumulated deficit	(684,744)	(651,073)
Total stockholders' equity	1,158,659	820,119
Total liabilities and stockholders' equity	$ 1,677,318	$ 1,351,571