Employee and Retiree Benefits (Deferred Compensation Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Aug. 25, 2018	Aug. 26, 2017	Aug. 27, 2016
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Employer discretionary contribution amount	$ 2.3	$ 1.6	$ 1.5
Key Employees [Member] | Non-Qualified Deferred Compensation Program (1981) [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Vesting age	55 years
Requisite service period	5 years
Requiste service period prior to December 1992	20 years
Deferred compensation expense	$ 1.1	1.2	$ 1.3
Officers and Managers [Member] | Supplemental Employee Retirement Plan (SERP) [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Contractual amount of years after retirement	15 years
Non-Qualified Share Option Program (2001) [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Deferred compensation assets	$ 1.0	1.6
Additional contribution at initiation	25.00%
Required option exercise period	15 years
Executive Deferred Compensation Plan 2007 [Member] | Officers and Key Employees [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Deferred compensation assets	$ 0.4	$ 0.4
Maximum salary deferral	50.00%
Maximum cash incentive award deferral	100.00%