Components of Net Deferred Taxes (Detail) - USD ($) $ in Thousands	Sep. 30, 2016	Sep. 30, 2015
Deferred tax assets:
Net operating loss carryforwards	$ 5,791	$ 7,367
Vacation accrual	3,367	3,295
Pension accrual	8,549	9,244
Allowance for bad debts	1,728	2,654
Fair value of derivative instruments		6,773
Insurance accrual	25,828	24,682
Inventory capitalization	1,128	1,038
Alternative minimum tax credit carryforward	266	266
Other, net	2,512	1,630
Total deferred tax assets	49,169	56,949
Valuation allowance	(3,053)	(3,027)
Net deferred tax assets	46,116	53,922
Deferred tax liabilities:
Property and equipment	3,999	2,831
Inventory costing method		497
Fair value of derivative instruments	788
Intangibles	35,976	34,286
Total deferred tax liabilities	40,763	37,614
Net deferred taxes	$ 5,353	$ 16,308