Stockholders' Equity - Additional Information (Detail) (USD $)	12 Months Ended						1 Months Ended	12 Months Ended		1 Months Ended		1 Months Ended	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2012 2.50% Convertible Notes	Dec. 31, 2011 2.50% Convertible Notes	May 23, 2011 2.50% Convertible Notes	Oct. 31, 2011 Stock Repurchase Program	Dec. 31, 2012 Stock Repurchase Program	Dec. 31, 2011 Stock Repurchase Program	Aug. 13, 2009 Stock Incentive Plan 2009	Dec. 31, 2012 Stock Incentive Plan 2009	Aug. 15, 2012 Amended and Restated Stock Incentive Plan 2009	Dec. 31, 2012 Warrant	Dec. 31, 2011 Warrant	Dec. 31, 2010 Warrant	Dec. 31, 2012 Restricted Stock	Dec. 31, 2011 Restricted Stock	Dec. 31, 2010 Restricted Stock	Dec. 31, 2012 Minimum	Dec. 31, 2012 Minimum Restricted Stock	Dec. 31, 2012 Maximum	Dec. 31, 2012 Maximum Restricted Stock
Class of Stock [Line Items]
Repurchase of common stock authorized value							$ 200,000,000
Period of common stock repurchase, years							3 years
Repurchase of common stock, shares								7,185,257	1,150,000
Repurchase of common stock, value	125,341,000	19,138,000						125,300,000	19,100,000
Stock repurchase, remaining available amount								55,500,000
Number of common stock shares authorized under Equity Incentive Plan										3,000,000		7,000,000
Plan expiration date										Aug. 13, 2019		Aug. 15, 2022
Number of additional common stock shares approved for issuance under amended and restated 2009 Equity Incentive Plan												4,000,000
Common stock reserved for issuance											3,832,063
Options grant, expected life	7 years																		5 years		10 years
Debt instrument, interest rate, stated percentage				2.50%	2.50%	2.50%
Weighted average contractual term of awards outstanding	2 years 6 months 22 days	3 years 1 month 2 days	2 years 9 months 15 days
Weighted average contractual term of awards exercisable	2 years 6 months 22 days	3 years 1 month 2 days	2 years 9 months 11 days
Fair value of options vested during the period		300,000	100,000
Weighted average grant date fair value per share of options granted during the period		$ 8.85	$ 7.30
Cash received from option exercise under all share-based payment arrangements	800,000	3,300,000	1,200,000
Tax benefit from share based payment arrangement	1,500,000	4,900,000	1,300,000
Aggregate intrinsic value of options exercised	5,200,000	11,600,000	7,500,000
Aggregate intrinsic value of options outstanding	23,700,000	18,600,000	38,100,000
Aggregate intrinsic value of options exercisable	23,700,000	18,600,000	38,100,000
Weighted average contractual term of awards outstanding and exercisable													4 years 7 months 28 days	5 years 5 months 23 days	4 years 11 months 19 days
Share based compensation awards vesting period																				1 year		5 years
Share based compensation awards granted in period																232,203	1,845,403	340,964
Share based compensation awards granted in period, fair market value																4,100,000	38,800,000	4,900,000
Compensation expense related to stock grants																11,500,000	11,400,000	11,300,000
Compensation cost not yet recognized																9,300,000
Compensation cost not yet recognized, period for recognition																4 years
Restricted common stock, value of shares withheld																$ 1,200,000	$ 3,200,000	$ 3,000,000