Earnings Per Share - Summary of Earnings Per Share, Basic and Diluted (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended					6 Months Ended
	Jun. 30, 2019	Mar. 31, 2019	Jun. 30, 2018		Mar. 31, 2018	Jun. 30, 2019		Jun. 30, 2018
Earnings Per Share [Abstract]
Net income	$ 261,651	$ 172,107	$ 176,852	[1]	$ 174,937	$ 433,758	[2]	$ 351,789	[1]
Denominator for basic earnings per share (in shares)	86,360		89,169	[1]		86,159		89,466	[1]
Dilutive securities (in shares)	3,771		3,533			3,535		3,504
Denominator for diluted earnings per share (in shares)	90,131		92,702	[1]		89,694		92,970	[1]
Basic earnings per share (in dollars per share)	$ 3.03		$ 1.98	[1]		$ 5.03		$ 3.93	[1]
Diluted earnings per share (in dollars per share)	$ 2.90		$ 1.91	[1]		$ 4.84		$ 3.78	[1]

[1] Reflects reclassifications from previously disclosed amounts to conform to current presentation.

[2] Reflects the impact of the Company's adoption of ASU 2016-02 "Leases", on January 1, 2019, using the modified retrospective transition method. Under this method, financial results reported in periods prior to 2019 are unchanged. Refer to footnote 2.