Common Stock and Share-Based Compensation - Summary of Stock Option Activity (Detail) (USD $)	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Options outstanding at January 1, 2014	5,055,035
Granted	0	0
Forfeited and canceled	(45,261)
Exercised	(171,350)
Options outstanding at March 31, 2014	4,838,424
Options exercisable at March 31, 2014	4,696,996
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Abstract]
Options outstanding at January 1, 2014, Weighted average exercise price	$ 19.35
Granted, Weighted average exercise price	$ 0.00
Forfeited and canceled, Weighted average exercise price	$ 19.85
Exercised, Weighted average exercise price	$ 14.52
Options outstanding at March 31, 2014, Weighted average exercise price	$ 19.51
Options exercisable at March 31, 2014, Weighted average exercise price	$ 19.77
Share-based Compensation Arrangement by Share-based Payment Award, Options, Additional Disclosures [Abstract]
Options outstanding at March 31, 2014, Weighted Average Contractual Life	3 years 5 months 1 day
Options exercisable at March 31, 2014, Weighted Average Contractual Life	3 years 3 months 11 days
Options outstanding at March 31, 2014, Aggregate Intrinsic Value	$ 3,293,624
Options exercisable at March 31, 2014, Aggregate Intrinsic Value	$ 2,757,231