Shareholders' Equity - Summary of Changes in Shareholders' Equity (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balance			$ 1,605,492
Cumulative-effect adjustment from adoption of ASU 2014-09, net of tax					$ 2,196
Net income	$ 203,174	$ 147,877	369,223	$ 250,800
Purchase of common stock for treasury			(483,538)
Equity-based compensation			28,104
Proceeds from Options exercised			86,094
Ending Balance	1,607,571		1,607,571
Common Stock [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balance			206
Ending Balance	206		206
Additional Paid-In-Capital [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balance			1,644,197
Equity-based compensation			28,104
Proceeds from Options exercised			86,094
Treasury stock issued upon option exercise and restricted share vesting			(36,699)
Ending Balance	1,721,696		1,721,696
Retained Earnings [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balance			6,231,940
Cumulative-effect adjustment from adoption of ASU 2014-09, net of tax					$ 2,196
Net income			369,223
Ending Balance	6,603,359		6,603,359
Treasury Stock [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balance			(6,270,851)
Purchase of common stock for treasury			(483,538)
Treasury stock issued upon option exercise and restricted share vesting			36,699
Ending Balance	(6,717,690)		(6,717,690)
Deferred Compensation Trust [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balance			(17,383)
Deferred compensation activity, net			235
Ending Balance	(17,148)		(17,148)
Deferred Compensation Liability [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balance			17,383
Deferred compensation activity, net			(235)
Ending Balance	$ 17,148		$ 17,148