Income Taxes (Additional Information) (Detail) - USD ($) $ in Thousands	3 Months Ended			9 Months Ended
	Jun. 30, 2020	Mar. 31, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Sep. 30, 2019
Business Acquisition [Line Items]
Other Tax Expense (Benefit)	$ 16,700
Operating Loss Carryforwards, Valuation Allowance		$ 6,500
(Benefit) provision for income taxes	16,660	$ (21,306)	$ (10,720)	$ 31,794	$ (12,129)
Deferred Foreign Income Tax Expense (Benefit)	$ 14,700
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent			21.00%	21.00%	21.00%
Deferred Income Tax Expense (Benefit)				$ 29,900
Effective Income Tax Rate Reconciliation, Percent			106.80%	(161.10%)	(394.60%)
Deferred Tax Assets, Net						$ 92,600