Summary of Significant Accounting Policies - Additional Information (Detail) - USD ($)	3 Months Ended
	Dec. 31, 2015	Sep. 30, 2015
Schedule Of Significant Accounting Policies [Line Items]
Accrued expenses and other current liabilities	$ 107,486,000	$ 107,745,000
Other long-term liabilities	27,123,000	$ 27,110,000
New England Teamsters & Trucking Industry Pension Fund
Schedule Of Significant Accounting Policies [Line Items]
Accrued expenses and other current liabilities	100,000
Other long-term liabilities	17,600,000
New England Teamsters & Trucking Industry Pension Fund | Significant Other Observable Inputs Level 2
Schedule Of Significant Accounting Policies [Line Items]
Multiemployer plan discounted withdrawal liability	16,000,000
Subsidiaries of Swiss Re
Schedule Of Significant Accounting Policies [Line Items]
Weather hedge contract, payment entitled to be received per heating degree-day shortfall	$ 35,000
Percentage in heating degree days less than ten year average that is covered	92.50%
Derivative maximum payout	$ 12,500,000
Derivative potential credit under normal weather conditions for remainder of fiscal year	5,200,000
Subsidiaries of Swiss Re | Delivery and branch expenses
Schedule Of Significant Accounting Policies [Line Items]
Credit on weather hedge contract	$ 12,500,000