Investments in Unconsolidated Joint Ventures (Schedule of combined financial information for the joint ventures on a 100% basis) (Details) - USD ($) $ in Millions	12 Months Ended
	May 31, 2020	May 26, 2019	May 27, 2018
Schedule of Equity Method Investments [Line Items]
Net sales	$ 2,045.6	$ 2,043.9	$ 2,164.4
Gross margin	785.3	744.4	853.6
Earnings before income taxes	214.0	155.4	216.2
Earnings after income taxes	176.5	111.9	176.7
Current assets	870.0	895.6
Noncurrent assets	781.4	839.2
Current liabilities	1,365.6	1,517.3
Noncurrent liabilities	104.2	77.1
Cereal Partners Worldwide [Member]
Schedule of Equity Method Investments [Line Items]
Net sales	1,654.3	1,647.7	1,734.0
Haagen Dazs Japan [Member]
Schedule of Equity Method Investments [Line Items]
Net sales	$ 391.3	$ 396.2	$ 430.4