Earnings per Share (Schedule of earnings per share) (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended
	Aug. 30, 2020	Aug. 25, 2019
Earnings Per Share [Abstract]
Net earnings attributable to General Mills	$ 638.9	$ 520.6
Average number of common shares - basic EPS	614.1	606.0
Earnings Per Share, Basic and Diluted [Abstract]
Average number of common shares - diluted EPS	619.8	611.5
Earnings per share - basic	$ 1.04	$ 0.86
Earnings per share - diluted	$ 1.03	$ 0.85
Other Disclosures [Abstract]
Anti-dilutive stock options, restricted stock units and performance share units	3.1	10.1
Stock Options [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Incremental share effect	3.2	3.1
Restricted Stock, Restricted Stock Units, and Other [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Incremental share effect	2.5	2.4