Stock-Based Compensation - Stock Option Activity (Detail) (USD $)	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Outstanding Options, Beginning Balance	120,638	145,069	222,446
Options Granted
Options Exercised	(93,484)	(23,189)	(57,027)
Options Canceled	(6,010)	(1,242)	(20,350)
Outstanding Options, Ending Balance	21,144	120,638	145,069
Weighted Average Exercise Price Per Share, Outstanding, Beginning Balance	$ 40.37	$ 38.08	$ 33.20
Options Vested	21,144
Weighted Average Exercise Price Per Share, Granted
Options Exercisable	21,144
Weighted Average Exercise Price Per Share, Exercised	$ 49.83	$ 31.35	$ 27.94
Weighted Average Exercise Price Per Share, Canceled	$ 36.31	$ 20.00	$ 31.71
Weighted Average Exercise Price Per Share, Outstanding, Ending Balance	$ 40.09	$ 40.37	$ 38.08
Weighted Average Exercise Price Per Share, Vested	$ 40.09
Weighted Average Exercise Price Per Share, Exercisable	$ 40.09
Weighted Average Remaining Contractual Life, Outstanding	1 year
Weighted Average Remaining Contractual Life, Vested	1 year
Weighted Average Remaining Contractual Life, Exercisable	1 year
Aggregate Intrinsic Value, Outstanding	$ 833,948
Aggregate Intrinsic Value, Vested	833,948
Aggregate Intrinsic Value, Exercisable	$ 833,948