Income Taxes (Components of Benefit from Income Taxes) (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
Income Tax Disclosure [Abstract]
Domestic	$ (4,557)		$ 425	$ (31,595)	$ (1,704)
Foreign	(12,103)		10,295	(199)	13,833
(Benefit) provision for income taxes	$ (16,660)	$ 21,306	$ 10,720	$ (31,794)	$ 12,129
Effective tax rate			106.80%	(161.10%)	(394.60%)