Shareholders' Equity - Summary of Changes in Shareholders' Equity (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balance	$ 2,341,244	$ 1,808,562
Net income	175,703	188,406
Treasury Stock, Value, Acquired, Cost Method	(216,582)	(216,499)
APIC, Share-based Payment Arrangement, Increase for Cost Recognition	7,492	19,333
APIC, Share-based Payment Arrangement, Recognition and Exercise	109,062	98,974
Ending Balance	2,416,919	1,898,776
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	2,055,407	1,820,223
APIC, Share-based Payment Arrangement, Increase for Cost Recognition	7,492	19,333
APIC, Share-based Payment Arrangement, Recognition and Exercise	109,062	98,974
Stock Issued During Period, Value, Stock Options Exercised	(44,646)	(39,430)
Ending Balance	2,127,315	1,899,100
Retained Earnings [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balance	7,909,872	7,031,333
Net income	175,703	188,406
Ending Balance	8,085,575	7,219,739
Treasury Stock [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balance	(7,624,241)	(7,043,200)
Treasury Stock, Value, Acquired, Cost Method	(216,582)	(216,499)
Stock Issued During Period, Value, Stock Options Exercised	44,646	39,430
Ending Balance	(7,796,177)	(7,220,269)
Deferred Compensation Trust [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balance	(16,912)	(16,937)
Deferred Compensation Activity Adjustments		25
Ending Balance	(16,912)	(16,912)
Deferred Compensation Liability [Member]
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning Balance	16,912	16,937
Deferred Compensation Activity Adjustments		(25)
Ending Balance	$ 16,912	$ 16,912