Supplemental Disclosure of Cash Flow Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2013
Cash paid during the period for:
Income taxes, net	$ 38,265	$ 25,518	$ 16,137
Interest	16,950	16,968	14,376
Non-cash investing activities:
Acquisition of NYC heating oil customer list	886
Non-cash financing activities:
Increase in interest expense-amortization of debt discount on 8.875% Senior Notes	$ 112	$ 112	$ 103