Summary of Significant Accounting Policies - Additional Information (Detail) - USD ($)		9 Months Ended
	Apr. 29, 2016	Jun. 30, 2016	Sep. 30, 2015
Schedule Of Significant Accounting Policies [Line Items]
Accrued expenses and other current liabilities		$ 122,932,000	$ 107,745,000
Other long-term liabilities		25,492,000	$ 27,110,000
New England Teamsters & Trucking Industry Pension Fund
Schedule Of Significant Accounting Policies [Line Items]
Accrued expenses and other current liabilities		200,000
Other long-term liabilities		17,500,000
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		18,400,000
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
Receipt of cash from weather hedge contract	$ 12,500,000