BUSINESS SEGMENTS AND RELATED INFORMATION - Schedule of Net Derivative Gains (Losses) from Economic Hedges of Forecasted Commodity Consumption and Foreign Currency Risk (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Feb. 28, 2021	Feb. 23, 2020	Feb. 28, 2021	Feb. 23, 2020
Derivative Instruments, Gain (Loss) [Line Items]
Gross derivative gains (losses) incurred			$ 5.7
Commodity contracts
Derivative Instruments, Gain (Loss) [Line Items]
Gross derivative gains (losses) incurred	$ 5.3	$ (5.7)	1.4	$ (12.5)
Commodity contracts | Reporting segments
Derivative Instruments, Gain (Loss) [Line Items]
Gross derivative gains (losses) incurred	(1.1)	(1.9)	(5.8)	(3.3)
Commodity contracts | Reporting segments | Net derivative gains (losses) allocated to Grocery & Snacks
Derivative Instruments, Gain (Loss) [Line Items]
Gross derivative gains (losses) incurred	0.3	(0.9)	(4.1)	(1.5)
Commodity contracts | Reporting segments | Net derivative losses allocated to Refrigerated & Frozen
Derivative Instruments, Gain (Loss) [Line Items]
Gross derivative gains (losses) incurred	(0.1)	0.0	(2.1)	(0.7)
Commodity contracts | Reporting segments | Net derivative gains (losses) allocated to International
Derivative Instruments, Gain (Loss) [Line Items]
Gross derivative gains (losses) incurred	(1.3)	(0.8)	1.1	(1.1)
Commodity contracts | Reporting segments | Net derivative losses allocated to Foodservice
Derivative Instruments, Gain (Loss) [Line Items]
Gross derivative gains (losses) incurred	0.0	(0.2)	(0.7)	0.0
Commodity contracts | Corporate
Derivative Instruments, Gain (Loss) [Line Items]
Gross derivative gains (losses) incurred	$ 6.4	$ (3.8)	$ 7.2	$ (9.2)