CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (USD $) In Thousands, except Share data, unless otherwise specified	Total	Common Stock	Additional Paid-In Capital	Receivable From Stock Option Exercises	Accumulated Other Comprehensive Income (Loss)	Accumulated Deficit
Balances at Dec. 31, 2009	$ 750,556	$ 62	$ 1,207,010	$ (5)	$ (1,962)	$ (454,549)
Balances (in shares) at Dec. 31, 2009		62,260,183
Increase (Decrease) in Stockholders' Equity
Stock-based compensation, related to stock option grants	6,863	1	6,863	(1)
Exercise of stock options (in shares)		323,436
Stock-based compensation, related to stock option and restricted stock unit grants	17,385		17,385
Issuance of common stock pursuant to employee stock purchase plan	2,129		2,129
Issuance of common stock pursuant to employee stock purchase plan (in shares)		78,991
Restricted stock units and awards issued, net of forfeitures	4,817		4,817
Restricted stock units and awards issued, net of forfeitures (in shares)		192,766
Comprehensive loss:
Change in unrealized gain (loss) on investments	732				732
Change in unrealized gain (loss) on cash flow hedges	(61)				(61)
Net income (loss)	(84,847)					(84,847)
Balances at Dec. 31, 2010	697,574	63	1,238,204	(6)	(1,291)	(539,396)
Balances (in shares) at Dec. 31, 2010		62,855,376
Increase (Decrease) in Stockholders' Equity
Stock-based compensation, related to stock option grants	21,688	1	22,115	(428)
Exercise of stock options (in shares)		819,370
Stock-based compensation, related to stock option and restricted stock unit grants	20,255		20,255
Issuance of common stock pursuant to employee stock purchase plan	2,601		2,601
Issuance of common stock pursuant to employee stock purchase plan (in shares)		80,160
Restricted stock units and awards issued, net of forfeitures	5,905		5,905
Restricted stock units and awards issued, net of forfeitures (in shares)		173,176
Comprehensive loss:
Change in unrealized gain (loss) on investments	(781)				(781)
Change in unrealized gain (loss) on cash flow hedges	61				61
Net income (loss)	76,110					76,110
Balances at Dec. 31, 2011	823,413	64	1,289,080	(434)	(2,011)	(463,286)
Balances (in shares) at Dec. 31, 2011	63,928,082	63,928,082
Increase (Decrease) in Stockholders' Equity
Stock-based compensation, related to stock option grants	76,236	2	76,334	(100)
Exercise of stock options (in shares)		2,576,984
Stock-based compensation, related to stock option and restricted stock unit grants	26,179		26,179
Issuance of common stock to Proteolix shareholders	62,933	1	62,932
Issuance of common stock to Proteolix shareholders (in shares)		860,707
Issuance of common stock pursuant to employee stock purchase plan	6,289		6,289
Issuance of common stock pursuant to employee stock purchase plan (in shares)		120,320
Restricted stock units and awards issued, net of forfeitures	10,771		10,771
Restricted stock units and awards issued, net of forfeitures (in shares)		(6,575)
Comprehensive loss:
Change in unrealized gain (loss) on investments	2,085				2,085
Net income (loss)	(187,787)					(187,787)
Balances at Dec. 31, 2012	$ 820,119	$ 67	$ 1,471,585	$ (534)	$ 74	$ (651,073)
Balances (in shares) at Dec. 31, 2012	67,479,518	67,479,518