Components of Accrued Expenses and Other Current Liabilities (Detail) - USD ($) $ in Thousands	Sep. 30, 2016	Sep. 30, 2015
Accrued Expenses and Other Current Liabilities [Line Items]
Accrued wages and benefits	$ 22,237	$ 27,930
Accrued insurance and environmental costs	70,037	67,101
Other accrued expenses and other current liabilities	11,581	12,714
Total accrued expenses and other current liabilities	$ 103,855	$ 107,745