Stock-Based Compensation - Additional Information (Detail) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares of common stock available for issuance	496,694		496,694
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			$ 7,493,000	$ 11,280,000
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	2,000,000	1,600,000	6,000,000	5,400,000
Unamortized stock-based compensation expense	100,000		100,000
Weighted-average remaining amortization period			5 months
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			38,128
Taxes paid related to net share settlement of restricted stock units			7,500,000
Unamortized stock-based compensation expense	$ 11,200,000		$ 11,200,000
Weighted-average remaining amortization period			1 year 2 months 12 days