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, 2017	Jun. 30, 2016		Jun. 30, 2017	Jun. 30, 2016
Earnings Per Share [Abstract]
Net income	$ 130,987	$ 116,253	[1]	$ 254,680	$ 227,343	[1],[2]
Denominator for basic earnings per share (in shares)	92,013	92,665	[1]	92,060	92,591	[1]
Dilutive securities (in shares)	2,210	2,614		2,332	2,546
Denominator for diluted earnings per share (in shares)	94,223	95,279	[1]	94,392	95,137	[1]
Basic earnings per share (in dollars per share)	$ 1.42	$ 1.25	[1]	$ 2.77	$ 2.46	[1]
Diluted earnings per share (in dollars per share)	$ 1.39	$ 1.22	[1]	$ 2.70	$ 2.39	[1]

[1] Reflects the impact of the Company's adoption of Accounting Standards Update 2016-09, Compensation-Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting, to simplify several aspects of the accounting for share-based compensation, including the income tax consequences.

[2] Reflects the impact of the Company's adoption of Accounting Standards Update 2016-09, Compensation-Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting, to simplify several aspects of the accounting for share-based compensation, including the income tax consequences.