Business Segment and Geographic Information (Schedule of net sales by class of similar products) (Details) - USD ($) $ in Millions	3 Months Ended
	Aug. 25, 2019	Aug. 26, 2018
Product Information [Line Items]
Net sales	$ 4,002.5	$ 4,094.0
Snacks [Member]
Product Information [Line Items]
Net sales	869.4	887.9
Cereal [Member]
Product Information [Line Items]
Net sales	685.5	677.1
Convenient meals [Member]
Product Information [Line Items]
Net sales	569.2	581.9
Yogurt [Member]
Product Information [Line Items]
Net sales	495.2	514.8
Pet [Member]
Product Information [Line Items]
Net sales	367.8	343.3
Baking mixes and ingredients [Member]
Product Information [Line Items]
Net sales	355.7	380.3
Dough [Member]
Product Information [Line Items]
Net sales	330.6	328.4
Super-premium ice cream [Member]
Product Information [Line Items]
Net sales	227.2	247.7
Other [Member]
Product Information [Line Items]
Net sales	$ 101.9	$ 132.6