Accrued Liabilities (Details) (USD $) In Thousands	Aug. 27, 2011	Aug. 28, 2010
Current liabilities [Abstract]
Payroll and benefit related	$ 28,362	$ 28,809
Insurance related	32,836	29,134
Environmental related	4,174	3,888
Other	11,258	13,074
Total current accrued liabilities	76,630	74,905
Long-term liabilities [Abstract]
Benefit related	16,016	15,192
Environmental related	14,194	15,098
Asset retirement obligations	9,488	8,899
Total long-term accrued liabilities	39,698	39,189
Total accrued liabilities	$ 116,328	$ 114,094

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