Fair Value Measurements (Narrative) (Details) $ in Millions	9 Months Ended	12 Months Ended
	Feb. 23, 2020 USD ($) restaurant	May 26, 2019 USD ($) restaurant
Impaired Long-Lived Assets Held and Used [Line Items]
Carrying value of long-term debt	$ 928.5	$ 927.7
Fair value of long-term debt	1,040.0	955.7
Long-lived assets	2,794.9	2,552.6
Significant unobservable inputs (Level 3)
Impaired Long-Lived Assets Held and Used [Line Items]
Impairment of long-lived assets	3.6	19.2
Significant unobservable inputs (Level 3) | Carrying Value
Impaired Long-Lived Assets Held and Used [Line Items]
Long-lived assets	$ 3.7	$ 21.7
Number of underperforming restaurants | restaurant	4	7
Significant unobservable inputs (Level 3) | Fair Value
Impaired Long-Lived Assets Held and Used [Line Items]
Assets held-for-sale, long-lived, fair value	$ 0.1	$ 2.5