Basis of Presentation - Schedule of Vesting Information Stock Options Outstanding (Detail) (USD $)	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Stock Options:
Unvested at beginning of period, Shares	609,029	157,298
Granted, Shares	43,686	122,357
Vested, Shares	(53,822)	(41,794)
Unvested at end of period, Shares	598,893	237,861
Unvested at beginning of period, Weighted-Average Exercise Price	$ 47.66	$ 38.57
Granted, Weighted-Average Exercise Price	$ 71.47	$ 47.50
Vested, Weighted-Average Exercise Price	$ 44.11	$ 34.30
Unvested at end of period, Weighted-Average Exercise Price	$ 49.72	$ 43.92