Net Periodic Benefit Expense (Income) (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Nov. 17, 2012	Nov. 19, 2011
Pension And Other Employee Benefit Plans [Line Items]
Interest cost	$ 2,659	$ 2,819
Expected return on plan assets	(3,083)	(2,704)
Amortization of net loss	3,333	2,260
Net periodic pension expense	$ 2,909	$ 2,375