Stock-based Compensation - Additional Information (Detail) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares of common stock available for issuance	493,104		493,104
Shares of common stock reserved for issuance	1,800,000		1,800,000
Vesting period of stock options in years			3 years
Taxes paid related to net share settlement of restricted stock units			$ 7,172,000	$ 11,208,000
Stock Options [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Contractual life in years			10 years
Recognized stock-based compensation expense	2,600,000	2,100,000	4,000,000	3,700,000
Unamortized stock-based compensation expense	100,000		100,000
Weighted-average remaining amortization period			7 months 6 days
Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Contractual life in years			3 years
RSUs paid to settle tax withholding obligations			36,427
Taxes paid related to net share settlement of restricted stock units			7,200,000
Unamortized stock-based compensation expense	$ 13,300,000		$ 13,300,000
Weighted-average remaining amortization period			1 year 6 months