Stock-Based Compensation (Tables)

12 Months Ended

Dec. 31, 2011

Stock-Based Compensation

Allocation of stock-based compensation expense included in the consolidated statements of operations

	Year Ended December 31,
(in thousands)	2011		2010		2009
Research and development	$	13,422	$	10,322	$	11,542
General and administrative		11,494		8,687		8,458
Total stock-based compensation expense	$	24,916	$	19,009	$	20,000

Schedule of stock-based compensation expense by award type included in the consolidated statements of operations

	Year Ended December 31,
(in thousands)	2011		2010		2009
Employee stock options	$	4,528	$	7,003	$	10,271
Employee RSUs		13,290		9,783		7,473
Employee RSAs		5,498		398		470
Non-employee options and RSUs		307		1,186		501
ESPP		1,293		639		1,285
Total stock-based compensation expense	$	24,916	$	19,009	$	20,000

Schedule of unrecognized compensation cost, net of expected forfeitures, and estimated weighted-average amortization period

(in thousands, except amortization period)	Unrecognized Compensation Cost		Weighted-average amortization period (years)
Stock options	$	7,293		2.8
RSUs	$	12,449		2.0
RSAs	$	5,389		4.5

Summary of equity award activity under the 2008 Plan and the 2004 Plan

(in thousands, except per share data)	Number of Shares Subject to Outstanding Options			Weighted- average Exercise Price of Outstanding Options		Number of Shares Subject to Outstanding RSUs			Weighted- average Fair Value per Share at Grant		Number of Shares Outstanding Subject to Vesting or Performance Conditions with vesting			Weighted- average Fair Value per Share at Grant
Balance at December 31, 2008		9,953		$	16.01		2,260		$	21.51		77		$	24.42
Granted		356			14.90		950			14.66		—			—
Exercised		(1,333	)		7.77		—			—		—			—
Released RSUs/RSAs		—			—		(603	)		14.62		(20	)		20.18
Forfeited		(562	)		25.43		(565	)		29.78		—			—
Balance at December 31, 2009		8,414			16.63		2,042			14.15		57			25.87
Granted		321			14.90		1,170			10.55		—			—
Exercised		(784	)		9.60		—			—		—			—
Released RSUs/RSAs		—			—		(657	)		13.20		(24	)		25.55
Forfeited		(297	)		26.17		(658	)		26.26		—			—
Balance at December 31, 2010		7,654			16.91		1,897			12.45		33			26.10
Granted		629			21.98		471			24.96		2,483			24.42
Exercised		(1,265	)		8.87		—			—		—			—
Released RSUs/RSAs		—			—		(797	)		13.89		(74	)		24.96
Forfeited		(127	)		29.15		(29	)		15.35		—			—
Balance at December 31, 2011		6,891			18.62		1,542			15.47		2,442			24.42

Schedule of weighted-average assumptions used to estimate the fair value of stock options granted

	Year Ended December 31,
	2011	2010	2009
Employee stock options
Risk-free interest rate	1.10% - 2.57%	1.11% - 2.82%	1.55% - 2.98%
Expected life (in years)	5 - 6	5 - 6	5 - 6
Volatility	0.49 - 0.55	0.48 - 0.52	0.48 - 0.57
Dividend yield	—%	—%	—%
Weighted-average estimated fair value of stock options granted	$11.11	$7.41	$7.48
Employee stock purchase plan issuances
Risk-free interest rate	0.05% - 0.54%	0.19% - 0.79%	0.17% - 0.88%
Expected life (in years)	0.5 - 2	0.5 - 2	0.5 - 2
Volatility	0.48 - 0.59	0.50 - 0.69	0.50 - 0.84
Dividend yield	—%	—%	—%
Weighted-average estimated fair value of ESPP issuances	$9.46	$7.63	$6.42

Schedule of outstanding options to purchase common stock based on range of stock option exercise prices

	Options Outstanding						Options Exercisable
Range of Exercise Prices	Number Outstanding		Weighted- average Remaining Contractual Life in Years		Weighted- average Exercise Prices		Options Exercisable		Weighted- average Remaining Contractual Life in Years		Weighted- average Exercise Price
$3.10		557		1.3	$	3.10		557		1.3	$	3.10
$6.15 - $6.70		145		6.9		6.19		99		6.9		6.18
$8.53		218		0.4		8.53		218		0.4		8.53
$9.69		1,172		2.3		9.69		1,172		2.3		9.69
$9.70 - $16.00		924		5.1		14.69		749		4.5		15.00
$16.01 - $21.96		1,493		5.6		18.52		1,061		4.1		18.34
$21.97 - $29.70		1,385		5.5		27.34		1,136		4.7		28.00
$29.71 - $35.46		997		5.2		33.52		997		5.2		33.52
Total		6,891		4.4		18.62		5,989		3.7		18.61