Stockholders' Equity - Additional Information (Detail) (USD $)	1 Months Ended		3 Months Ended	9 Months Ended			9 Months Ended	3 Months Ended		9 Months Ended			3 Months Ended		9 Months Ended		3 Months Ended
	May 23, 2013	Feb. 28, 2013	Jun. 30, 2013	Sep. 30, 2013 Plans	Sep. 30, 2013 Restricted Stock [Member]	Dec. 31, 2012 Restricted Stock [Member]	Sep. 30, 2013 Performance Based Restricted Stock Unit [Member]	Sep. 30, 2013 Employee Stock Option [Member]	Sep. 30, 2012 Employee Stock Option [Member]	Sep. 30, 2013 Employee Stock Option [Member]	Sep. 30, 2012 Employee Stock Option [Member]	Sep. 30, 2013 Performance Based Stock Options [Member]	Sep. 30, 2013 Incentive Stock Options [Member]	Sep. 30, 2012 Incentive Stock Options [Member]	Sep. 30, 2013 Incentive Stock Options [Member]	Sep. 30, 2012 Incentive Stock Options [Member]	Jun. 30, 2013 Repurchase of Equity [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Option available for future grants				2,300,000
Number of stock based compensation plans				5
Stock incentive plan	1,600,000
Aggregate intrinsic value price per share					$ 14.88			$ 14.88		$ 14.88
Unrecognized stock-based compensation cost					$ 5,400,000			$ 300,000		$ 300,000
Weighted average period					29 months
Approximate units of performance restricted stock granted							149,000
Approximate units outstanding					1,115,177	582,212	227,000
Performance criteria met for approximate units					158,700		85,000
Options exercised, aggregate intrinsic value								5,300,000	700,000	9,100,000	1,600,000
Weighted average vesting period				9 months
Performance-based stock options Cumulative Granted												400,000
Performance-based stock options condition met												100,000
Unvested performance options												300,000
Fair value of Unvested performance options												47,000
Incremental stock option expense													22,000	98,000
Total share-based compensation expense															85,000.0	300,000
Outstanding common stock repurchase program Authorized Amount		25,000,000
Shares repurchased			3,048,966
Additional stock repurchase program authorized amount			$ 25,000,000
Average cost of repurchase per share			$ 8.17														$ 8.20