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, 2017	Jun. 30, 2016	Sep. 30, 2016
New Accounting Pronouncement Early Adoption [Line Items]
Net cash provided from operating activities		$ 411,328	$ 173,201
Net cash used in financing activities		$ 70,496	(99,008)
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)