Litigation - Additional Information (Detail) (USD $) In Thousands, unless otherwise specified	9 Months Ended
	May 09, 2015
Loss Contingencies [Line Items]
Site contingency, recovery from third party of environmental remediation cost	In 2004, the Company acquired a store site in Mount Ephraim, New Jersey that had previously been the site of a gasoline service station and contained evidence of groundwater contamination. Upon acquisition, the Company voluntarily reported the groundwater contamination issue to the New Jersey Department of Environmental Protection and entered into a Voluntary Remediation Agreement providing for the remediation of the contamination associated with the property. The Company has conducted and paid for (at an immaterial cost to the Company) remediation of contamination on the property. The Company is also investigating, and will be addressing, potential vapor intrusion impacts in downgradient residences and businesses. The New Jersey Department of Environmental Protection (“NJDEP”) has asserted, in a Directive and Notice to Insurers dated February 19, 2013 and again in an Amended Directive and Notice to Insurers dated January 13, 2014 (collectively the “Directives”), that the Company is liable for the downgradient impacts under a joint and severable liability theory. By letter dated April 23, 2015, NJDEP has demanded payment from the Company, and other parties, in the amount of approximately $296 thousand for costs incurred by NJDEP in connection with contamination downgradient of the property. The Company has contested, and will continue to contest, any such assertions due to the existence of other entities/sources of contamination, some of which are named in the Directives and the April 23, 2015 Demand, in the area of the property. Pursuant to the Voluntary Remediation Agreement, upon completion of all remediation required by the agreement, the Company believes it should be eligible to be reimbursed up to 75 percent of qualified remediation costs by the State of New Jersey. The Company has asked the state for clarification that the agreement applies to off-site work, and the state is considering the request. Although the aggregate amount of additional costs that the Company may incur pursuant to the remediation cannot currently be ascertained, the Company does not currently believe that fulfillment of its obligations under the agreement or otherwise will result in costs that are material to its financial condition, results of operations or cash flow.
Received a subpoena from the District Attorney of the County of Alameda and other legal proceedings	In July 2014, the Company received a subpoena from the District Attorney of the County of Alameda, along with other environmental prosecutorial offices in the state of California, seeking documents and information related to the handling, storage and disposal of hazardous waste. The Company is cooperating fully with the request and cannot predict the ultimate outcome of these efforts.The Company is involved in various other legal proceedings incidental to the conduct of its business, including several lawsuits containing class-action allegations in which the plaintiffs are current and former hourly and salaried employees who allege various wage and hour violations and unlawful termination practices. The Company does not currently believe that, either individually or in the aggregate, these matters will result in liabilities material to the Company’s financial condition, results of operations or cash flows.
New Jersey Department of Environmental Protection [Member]
Loss Contingencies [Line Items]
Litigation settlement amount demanded by plaintiff	296
Maximum [Member]
Loss Contingencies [Line Items]
Reimbursable remediation costs	75.00%