New Accounting Standards - Summary of Adjustments to Quarterly Data Resulting from Adoption of New Standard in Statements of Cash Flows (Detail) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended	9 Months Ended
	Mar. 31, 2016	Jun. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
New Accounting Pronouncement Early Adoption [Line Items]
Net cash provided from operating activities			$ 600,532	$ 205,837
Net cash used in financing activities			$ 191,476	(39,029)
Accounting Standards Update 2016-09
New Accounting Pronouncement Early Adoption [Line Items]
Net cash provided from operating activities	$ 90,785	$ 173,201		205,837
Net cash used in financing activities	(75,834)	(99,008)		(39,029)
Accounting Standards Update 2016-09 | As Reported
New Accounting Pronouncement Early Adoption [Line Items]
Net cash provided from operating activities	87,424	169,604		202,037
Net cash used in financing activities	$ (72,473)	$ (95,411)		$ (35,229)