Stock-Based Compensation (Tables)

12 Months Ended

Dec. 31, 2012

Stock-Based Compensation

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

	Year Ended December 31,
(in thousands)	2012		2011		2010
Research and development	$	13,667	$	13,422	$	10,322
General and administrative		10,116		11,494		8,687
Total stock-based compensation expense	$	23,783	$	24,916	$	19,009

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

	Year Ended December 31,
(in thousands)	2012		2011		2010
Employee stock options	$	3,417	$	4,528	$	7,003
Employee RSUs		11,546		13,290		9,783
Employee RSAs		7,968		5,498		398
Non-employee options and RSUs		—		307		1,186
ESPP		852		1,293		639
Total stock-based compensation expense	$	23,783	$	24,916	$	19,009

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	$	6,442		2.6
RSUs		14,027		2.1
RSAs		23,525		3.5
Total unrecognized stock-based compensation expense	$	43,994

Summary of equity award activity under the 2008 and 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, 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			24.61
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			24.62
Granted		335			21.91		528			18.45		447			18.11
Exercised		(947	)		7.98		—			—		—			—
Released RSUs/RSAs		—			—		(752	)		14.19		(388	)		24.77
Forfeited		(159	)		24.43		(78	)		18.48		—			—
Balance at December 31, 2012		6,120			20.30		1,240			17.32		2,501			23.43

Schedule of weighted-average assumptions used to estimate the fair value of stock options granted and employee stock purchase plan issuances

	Year Ended December 31,
	2012	2011	2010
Employee stock options
Risk-free interest rate	0.74% - 1.17%	1.10% - 2.57%	1.11% - 2.82%
Expected life (in years)	5 - 6	5 - 6	5 - 6
Volatility	55% - 60%	49% - 55%	48% - 52%
Dividend yield	—%	—%	—%
Weighted-average estimated fair value of stock options granted	$11.50	$11.11	$7.41
Employee stock purchase plan issuances
Risk-free interest rate	0.14% - 0.29%	0.05% - 0.54%	0.19% - 0.79%
Expected life (in years)	0.5 - 2	0.5 - 2	0.5 - 2
Volatility	51% - 64%	48% - 59%	50% - 69%
Dividend yield	—%	—%	—%
Weighted-average estimated fair value of ESPP issuances	$8.07	$9.46	$7.63

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

 As of December 31, 2012, all outstanding options to purchase common stock of the Company are summarized in the following table (in thousands, except years and per share data):

	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		191		0.8	$	3.10		191		0.8	$	3.10
$6.15 - $6.70		25		5.9		6.15		25		5.9		6.15
$9.69		1,140		1.3		9.69		1,140		1.3		9.69
$9.70 - $16.00		839		4.1		14.71		768		3.8		14.87
$16.01 - $19.80		1,228		4.5		18.17		956		3.3		18.13
$19.81 - $24.71		594		7.2		22.16		316		5.7		22.38
$24.72 - $29.70		1,124		4.1		28.29		1,038		3.6		28.42
$29.71 - $35.46		979		4.1		33.52		979		4.1		33.52
Total		6,120		3.8		20.30		5,413		3.2		20.31