Shareholders' Equity - Summary of Changes in Shareholders' Equity (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balance	$ 1,304,441
Cumulative-effect adjustment from adoption of ASU 2016-09, net of tax	609
Net income	102,923	$ 65,303
Purchase of common stock for treasury	(85,547)
Equity-based compensation	10,589
Proceeds from stock options exercised	75,265
Ending Balance	1,408,280
Common Stock [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balance	206
Ending Balance	206
Additional Paid-In-Capital [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balance	1,515,828
Cumulative-effect adjustment from adoption of ASU 2016-09, net of tax	1,566
Equity-based compensation	10,589
Proceeds from stock options exercised	75,265
Treasury stock issued upon option exercise and restricted share vesting	(32,978)
Ending Balance	1,570,270
Retained Earnings [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balance	5,695,376
Cumulative-effect adjustment from adoption of ASU 2016-09, net of tax	(957)
Net income	102,923
Ending Balance	5,797,342
Treasury Stock [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balance	(5,906,969)
Purchase of common stock for treasury	(85,547)
Treasury stock issued upon option exercise and restricted share vesting	32,978
Ending Balance	(5,959,538)
Deferred Compensation Trust [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balance	(17,375)
Deferred compensation activity	(8)
Ending Balance	(17,383)
Deferred Compensation Liability [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balance	17,375
Deferred compensation activity	8
Ending Balance	$ 17,383