Supplemental Disclosure of Cash Flow Information (Detail) - USD ($) $ in Thousands	9 Months Ended
	Jun. 30, 2017	Jun. 30, 2016
Cash paid during the period for:
Income taxes, net	$ 4,116	$ 15,411
Interest	6,002	5,082
Non-cash operating activities:
Increase in interest expense-amortization of deferred charges on senior secured term loan	$ 225	$ 214