Stock-Based Compensation - SAR Activity (Detail) (Stock Appreciation Rights [Member], USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Stock Appreciation Rights [Member]
Schedule Of Stock Appreciation Rights Activity [Line Items]
SARs Outstanding, Beginning Balance	687,190	1,162,705	1,246,495
Granted, SARs	60,588	100,914	96,765
Exercised, SARs	(374,667)	(567,953)	(180,555)
Canceled, SARs	(3,514)	(8,476)
Shares Outstanding, SARs, Ending Balance	369,597	687,190	1,162,705
Outstanding, Weighted Average Grant Price Per Share, Beginning Balance	$ 18.56	$ 13.17	$ 13.70
Vested, SARs	230,604
Granted, Weighted Average Grant Price Per Share	$ 43.89	$ 25.75	$ 25.76
Exercisable, SARs	230,604
Exercised, Weighted Average Grant Price Per Share	$ 15.39	$ 13.08	$ 28.34
Canceled, Weighted Average Grant Price Per Share	$ 26.20	$ 24.15
Outstanding, Weighted Average Grant Price Per Share, Ending Balance	$ 25.85	$ 18.56	$ 13.17
Vested, Weighted Average Grant Price Per Share	$ 21.37
Exercisable, Weighted Average Grant Price Per Share	$ 21.37
Weighted Average Remaining Contractual Life, Outstanding	6 years 10 months 24 days
Weighted Average Remaining Contractual Life, Vested	6 years
Weighted Average Remaining Contractual Life, Exercisable	6 years
Aggregate Intrinsic Value, Outstanding	$ 2,547,706
Aggregate Intrinsic Value, Vested	1,386,104
Aggregate Intrinsic Value, Exercisable	$ 1,386,104