Shareholders' Equity - Summary of Changes in Shareholders' Equity (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2017
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balance	$ 1,808,562	$ 1,605,492
Cumulative-effect adjustment from adoption of ASU 2014-09, net of tax			$ 2,196
Net income	188,406	166,049
Purchase of common stock for treasury	(216,499)	(357,242)
Equity-based compensation	19,333	9,509
Proceeds from Options exercised	98,974	40,804
Ending Balance	1,898,776	1,466,808
Common Stock [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balance	206	206
Ending Balance	206	206
Additional Paid-In-Capital [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balance	1,820,223	1,644,197
Equity-based compensation	19,333	9,509
Proceeds from Options exercised	98,974	40,804
Treasury stock issued upon option exercise and restricted share vesting	(39,430)	(16,410)
Ending Balance	1,899,100	1,678,100
Retained Earnings [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balance	7,031,333	6,231,940
Cumulative-effect adjustment from adoption of ASU 2014-09, net of tax			$ 2,196
Net income	188,406	166,049
Ending Balance	7,219,739	6,400,185
Treasury Stock [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balance	(7,043,200)	(6,270,851)
Purchase of common stock for treasury	(216,499)	(357,242)
Treasury stock issued upon option exercise and restricted share vesting	39,430	16,410
Ending Balance	(7,220,269)	(6,611,683)
Deferred Compensation Trust [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balance	(16,937)	(17,383)
Deferred compensation activity, net	25	(6)
Ending Balance	(16,912)	(17,389)
Deferred Compensation Liability [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balance	16,937	17,383
Deferred compensation activity, net	(25)	6
Ending Balance	$ 16,912	$ 17,389