Supplemental Disclosure of Cash Flow Information - Schedule of Supplemental Disclosure of Cash Flow Information (Detail) - USD ($) $ in Thousands	9 Months Ended
	Jun. 30, 2020		Jun. 30, 2019
Cash paid during the period for:
Income taxes, net	$ 9,988	[1]	$ 3,046
Interest	$ 9,272		$ 9,709

[1] In July 2020, the Company made $8.5 million in tax payments that were deferred from April and June.