Share-Based Compensation - Stock Option Activity (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Number of Shares, Outstanding Beginning Balance	5,537	5,720	5,711
Number of Shares, Granted	747	675	1,453
Number of Shares, Exercised	(1,118)	(855)	(1,443)
Number of Shares, Forfeited	(2)	(3)	(1)
Number of Shares, Outstanding Ending Balance	5,164	5,537	5,720
Number of Shares, Exercisable at December 31, 2015	1,940
Weighted Average Exercise Price, Outstanding	$ 44.61	$ 34.66	$ 20.86
Weighted Average Exercise Price, Granted	145.71	94.15	67.08
Weighted Average Exercise Price, Exercised	20.71	17.17	12.68
Weighted Average Exercise Price, Forfeited	19.61	37.44	68.17
Weighted Average Exercise Price, Outstanding	64.43	$ 44.61	$ 34.66
Weighted Average Exercise Price, Exercisable at December 31, 2015	$ 40.69
Weighted Average Remaining Contractual Life (Years), Outstanding at December 31, 2015	7 years
Weighted Average Remaining Contractual Life (Years), Exercisable at December 31, 2015	6 years
Aggregate Intrinsic Value, Outstanding at December 31, 2015	$ 568,239
Aggregate Intrinsic Value, Exercisable at December 31, 2015	$ 259,257