Shareholders' Equity - Summary of Changes in Shareholders' Equity (Detail) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balance	$ 3,046,507	$ 2,416,919	$ 3,103,074	$ 2,341,244
Net income	321,295	164,075	570,057	339,778
Purchase of common stock for treasury	(376,941)		(754,366)	(216,582)
Equity-based compensation	13,379	14,434	27,850	21,926
Proceeds from Options exercised	38,048	16,984	95,673	126,046
Ending Balance	$ 3,042,288	2,612,412	$ 3,042,288	$ 2,612,412
Common stock repurchased (in shares)	78		165	58
Common Stock [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balance	$ 206	206	$ 206	$ 206
Ending Balance	206	206	206	206
Additional Paid-in Capital [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balance	2,272,006	2,127,315	2,214,426	2,055,407
Equity-based compensation	13,379	14,434	27,850	21,926
Proceeds from Options exercised	38,048	16,984	95,673	126,046
Treasury stock issued upon option exercise and restricted share vesting	(8,869)	(7,110)	(23,385)	(51,756)
Ending Balance	2,314,564	2,151,623	2,314,564	2,151,623
Retained Earnings [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balance	9,059,882	8,085,575	8,811,120	7,909,872
Net income	321,295	164,075	570,057	339,778
Ending Balance	9,381,177	8,249,650	9,381,177	8,249,650
Treasury Stock [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balance	(8,285,587)	(7,796,177)	(7,922,678)	(7,624,241)
Purchase of common stock for treasury	(376,941)		(754,366)	(216,582)
Treasury stock issued upon option exercise and restricted share vesting	(8,869)	(7,110)	(23,385)	(51,756)
Ending Balance	(8,653,659)	(7,789,067)	(8,653,659)	(7,789,067)
Deferred Compensation Trust [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balance	(16,710)	(16,912)	(16,710)	(16,912)
Ending Balance	(16,710)	(16,710)	(16,710)	(16,710)
Deferred Compensation Activity Adjustments		(202)		(202)
Deferred Compensation Liability [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balance	16,710	16,912	16,710	16,912
Ending Balance	$ 16,710	16,710	$ 16,710	16,710
Deferred Compensation Activity Adjustments		$ (202)		$ (202)