Stock-Based Compensation - Additional Information (Detail) (USD $)	3 Months Ended	9 Months Ended
	Sep. 30, 2013	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013 Employee Stock Purchase Plan	Jun. 06, 2012 Employee Stock Purchase Plan	Sep. 30, 2013 2008 Equity Incentive Plan	Jun. 12, 2013 2008 Equity Incentive Plan	Jun. 06, 2012 2008 Equity Incentive Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Increase in shares of common stock authorized for issuance					500,000		6,000,000	3,000,000
Maximum number of shares of common stock authorized for issuance					1,320,500			19,540,940
Aggregate number of shares of common stock reserved for future issuance	12,700,000	12,700,000
Outstanding options and other stock based awards	10,600,000	10,600,000
Number of shares available for future issuance				500,000		8,100,000
Restricted stock units vesting Description		The restricted stock units vest in three annual installments from the date of grant and are generally issuable at the end of the three-year vesting term
Performance-based stock options awards	$ 0		$ 0
Performance-based stock options, outstanding	50,000	50,000