Weighted Average Asset Allocation for Pension Plan Assets (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Aug. 25, 2012	Aug. 27, 2011	Aug. 28, 2010
Asset Allocation Fair Value	$ 181,409	$ 156,883	$ 117,243
Asset Allocation Actual	100.00%	100.00%
Asset Allocation Target	100.00%	100.00%
U.S. equities [Member]
Asset Allocation Fair Value	51,101	40,092
Asset Allocation Actual	28.20%	25.50%
Asset Allocation Target	30.00%	30.00%
International equities [Member]
Asset Allocation Fair Value	31,767	28,378
Asset Allocation Actual	17.50%	18.10%
Asset Allocation Target	20.00%	20.00%
Emerging equities [Member]
Asset Allocation Fair Value	16,471	12,086
Asset Allocation Actual	9.10%	7.70%
Asset Allocation Target	10.00%	10.00%
High yield equities [Member]
Asset Allocation Fair Value	17,378	12,547
Asset Allocation Actual	9.60%	8.00%
Asset Allocation Target	10.00%	10.00%
Alternative investments [Member]
Asset Allocation Fair Value	2,404	2,807
Asset Allocation Actual	1.30%	1.80%
Fixed income securities [Member]
Asset Allocation Fair Value	47,667	27,321
Asset Allocation Actual	26.30%	17.40%
Asset Allocation Target	30.00%	30.00%
Cash and cash equivalents [Member]
Asset Allocation Fair Value	14,621	31,178
Asset Allocation Actual	8.00%	19.90%
Real estate [Member]
Asset Allocation Fair Value		2,474
Asset Allocation Actual		1.60%
Level 1 [Member]
Asset Allocation Fair Value
Level 1 [Member] | U.S. equities [Member]
Asset Allocation Fair Value
Level 1 [Member] | International equities [Member]
Asset Allocation Fair Value
Level 1 [Member] | Emerging equities [Member]
Asset Allocation Fair Value
Level 1 [Member] | High yield equities [Member]
Asset Allocation Fair Value
Level 1 [Member] | Alternative investments [Member]
Asset Allocation Fair Value
Level 1 [Member] | Fixed income securities [Member]
Asset Allocation Fair Value
Level 1 [Member] | Cash and cash equivalents [Member]
Asset Allocation Fair Value
Level 1 [Member] | Real estate [Member]
Asset Allocation Fair Value
Level 2 [Member]
Asset Allocation Fair Value	179,005	151,602
Level 2 [Member] | U.S. equities [Member]
Asset Allocation Fair Value	51,101	40,092
Level 2 [Member] | International equities [Member]
Asset Allocation Fair Value	31,767	28,378
Level 2 [Member] | Emerging equities [Member]
Asset Allocation Fair Value	16,471	12,086
Level 2 [Member] | High yield equities [Member]
Asset Allocation Fair Value	17,378	12,547
Level 2 [Member] | Fixed income securities [Member]
Asset Allocation Fair Value	47,667	27,321
Level 2 [Member] | Cash and cash equivalents [Member]
Asset Allocation Fair Value	14,621	31,178
Level 3 [Member]
Asset Allocation Fair Value	2,404	5,281
Level 3 [Member] | Alternative investments [Member]
Asset Allocation Fair Value	2,404	2,807
Level 3 [Member] | Real estate [Member]
Asset Allocation Fair Value		$ 2,474