Employee Benefit Plans - Narrative (Details) $ in Millions	3 Months Ended		6 Months Ended
	Feb. 23, 2019 USD ($) Retirement-Plan	Feb. 24, 2018 USD ($)	Feb. 23, 2019 USD ($) Retirement-Plan	Feb. 24, 2018 USD ($)
Postemployment Benefits [Abstract]
Contributions charged to expense under the plan	$ 4.3	$ 3.9	$ 8.8	$ 8.0
Number of frozen non-contributory defined benefit pension plans | Retirement-Plan	2		2
Amounts charged to expense related to the plans	$ 0.5	$ 0.6	$ 1.1	$ 1.3