Stock-Based Compensation - Stock Option Activity Under Equity Incentive Plans (Detail) (Stock options [Member], USD $) In Thousands, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2012
Stock options [Member]
Schedule Of Stock Option Activity [Line Items]
Number of Shares outstanding, Beginning balance	17,046
Number of Shares, Options granted	3,435
Number of Shares, Options exercised	(631)
Number of Shares, Options forfeited & canceled	(852)
Number of Shares outstanding, Ending balance	18,998
Vested & Expected to Vest, Outstanding Number of Shares	18,688
Exercisable, Number of Shares	13,449
Weighted Average Exercise Price per Share, Outstanding, Beginning balance	$ 9.29
Weighted Average Exercise Price per Share, Options granted	$ 7.46
Weighted Average Exercise Price per Share, Options exercised	$ 5.48
Weighted Average Exercise Price per Share, Options forfeited & Canceled	$ 10.34
Weighted Average Exercise Price per Share , Outstanding, Ending balance	$ 9.03
Vested and expected to vest, Weighted-Average Exercise Price per Share	$ 9.04
Exercisable, Weighted Average Exercise Price per Share	$ 9.05
Weighted-Average Remaining Contractual Life, Outstanding	4 years 8 months 23 days
Vested and expected to Vest, Weighted-Average Remaining Contractual Life	4 years 8 months 12 days
Exercisable, Weighted-Average Remaining Contractual Life	4 years 15 days
Aggregate Intrinsic Value, Outstanding	$ 10,972
Vested and expected to Vest, Aggregate Intrinsic Value	10,916
Exercisable, Aggregate Intrinsic Value	$ 9,874