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 27, 2018	May 28, 2017	May 29, 2016
Schedule of Equity Method Investments [Line Items]
Net sales	$ 2,164.4	$ 2,083.5	$ 2,044.2
Gross margin	853.6	865.9	867.6
Earnings before income taxes	216.2	243.3	234.8
Earnings after income taxes	176.7	190.3	186.7
Current assets	938.5	849.7
Noncurrent assets	902.5	858.9
Current liabilities	1,579.3	1,469.6
Noncurrent liabilities	72.6	55.2
Cereal Partners Worldwide [Member]
Schedule of Equity Method Investments [Line Items]
Net sales	1,734.0	1,648.4	1,674.8
Haagen Dazs Japan [Member]
Schedule of Equity Method Investments [Line Items]
Net sales	$ 430.4	$ 435.1	$ 369.4