Employee and Retiree Benefits (Changes in Postretirement Health Care Liability) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Aug. 25, 2012	Aug. 27, 2011	Aug. 28, 2010
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Balance at beginning of year	$ 41,370	$ 40,327
Interest cost	1,849	1,905	1,979
Service cost	539	608	555
Net benefits paid	(1,213)	(1,228)
Actuarial loss	7,185	(242)
Plan amendment	(4,598)	0
Balance at end of year	$ 45,132	$ 41,370	$ 40,327