Quarterly Data (Unaudited) (Schedule of summarized quarterly data) (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended								12 Months Ended
	May 31, 2020	Feb. 23, 2020	Nov. 24, 2019	Aug. 25, 2019	May 26, 2019	Feb. 24, 2019	Nov. 25, 2018	Aug. 26, 2018	May 31, 2020	May 26, 2019	May 27, 2018
QUARTERLY DATA (UNAUDITED) [Abstract]
Net sales	$ 5,023.0	$ 4,180.3	$ 4,420.8	$ 4,002.5	$ 4,161.7	$ 4,198.3	$ 4,411.2	$ 4,094.0	$ 17,626.6	$ 16,865.2	$ 15,740.4
Gross Margin	1,768.1	1,403.2	1,569.1	1,389.5	1,461.3	1,443.0	1,509.7	1,342.8
Net earnings attributable to General Mills	$ 625.7	$ 454.1	$ 580.8	$ 520.6	$ 570.2	$ 446.8	$ 343.4	$ 392.3	$ 2,181.2	$ 1,752.7	$ 2,131.0
Earnings per share - basic	$ 1.03	$ 0.75	$ 0.96	$ 0.86	$ 0.95	$ 0.74	$ 0.57	$ 0.66	$ 3.59	$ 2.92	$ 3.69
Earnings per share - diluted	$ 1.02	$ 0.74	$ 0.95	$ 0.85	$ 0.94	$ 0.74	$ 0.57	$ 0.65	3.56	2.90	3.64
Dividends per share									$ 1.96	$ 1.96	$ 1.96