Business Segment and Geographic Information (Schedule of operating segment results) (Details) - USD ($) $ in Millions	3 Months Ended
	Aug. 25, 2019	Aug. 26, 2018
Segment Reporting Information [Line Items]
Net sales	$ 4,002.5	$ 4,094.0
Operating profit	662.4	601.5
Restructuring, impairment, and other exit costs (recoveries)	8.2	(1.4)
Operating Segments [Member]
Segment Reporting Information [Line Items]
Net sales	4,002.5	4,094.0
Operating profit	769.6	706.4
Unallocated Corporate Items [Member]
Segment Reporting Information [Line Items]
Operating profit	99.0	106.3
North America Retail [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Net sales	2,376.1	2,387.8
Operating profit	559.9	548.1
U.S. Meals & Baking [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Net sales	830.6	837.5
U.S. Cereal [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Net sales	589.9	584.4
U.S. Snacks [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Net sales	528.2	533.5
U.S. Yogurt & Other [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Net sales	219.2	219.1
Canada [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Net sales	208.2	213.3
Europe & Australia [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Net sales	454.1	500.7
Operating profit	27.6	34.5
Convenience Stores & Foodservice [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Net sales	445.0	463.2
Operating profit	91.1	97.1
Pet [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Net sales	367.8	343.3
Operating profit	80.9	14.5
Asia & Latin America [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Net sales	359.5	399.0
Operating profit	$ 10.1	$ 12.2