GOODWILL AND OTHER IDENTIFIABLE INTANGIBLE ASSETS - Schedule of Change in Carrying Amount of Goodwill, Excluding Amounts Classified as Held for Sale (Details) $ in Millions	9 Months Ended
	Feb. 28, 2021 USD ($)
Goodwill
Balance as of May 31, 2020	$ 11,389.0
Currency translation	6.6
Balance as of February 28, 2021	11,395.6
Grocery & Snacks
Goodwill
Balance as of May 31, 2020	4,698.2
Currency translation	0.0
Balance as of February 28, 2021	4,698.2
Refrigerated & Frozen
Goodwill
Balance as of May 31, 2020	5,648.3
Currency translation	0.0
Balance as of February 28, 2021	5,648.3
International
Goodwill
Balance as of May 31, 2020	290.5
Currency translation	6.6
Balance as of February 28, 2021	297.1
Foodservice
Goodwill
Balance as of May 31, 2020	752.0
Currency translation	0.0
Balance as of February 28, 2021	$ 752.0