Earnings per Share (Schedule of earnings per share) (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended		9 Months Ended
	Feb. 28, 2021	Feb. 23, 2020	Feb. 28, 2021	Feb. 23, 2020
Earnings Per Share [Abstract]
Net earnings attributable to General Mills	$ 595.7	$ 454.1	$ 1,923.0	$ 1,555.5
Average number of common shares - basic EPS	615.0	607.9	614.6	607.1
Earnings Per Share, Basic and Diluted [Abstract]
Average number of common shares - diluted EPS	619.4	612.8	619.6	612.1
Earnings per share - basic	$ 0.97	$ 0.75	$ 3.13	$ 2.56
Earnings per share - diluted	$ 0.96	$ 0.74	$ 3.10	$ 2.54
Stock Options [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Incremental share effect	2.0	2.6	2.6	2.8
Restricted stock units and performance share units [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Incremental share effect	2.4	2.3	2.4	2.2