Employee Benefit Plans - Narrative (Details) $ in Millions	3 Months Ended		6 Months Ended
	Feb. 29, 2020 USD ($) Retirement-Plan	Feb. 23, 2019 USD ($)	Feb. 29, 2020 USD ($) Retirement-Plan	Feb. 23, 2019 USD ($)
Postemployment Benefits [Abstract]
Contributions charged to expense under the plan	$ 5.0	$ 4.3	$ 10.5	$ 8.8
Number of frozen non-contributory defined benefit pension plans | Retirement-Plan	2		2
Amounts charged to expense (benefit) related to the plans	$ (0.3)	$ 0.5	$ 0.4	$ 1.1