Earnings per Share (Schedule of earnings per share) (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions		3 Months Ended
		Aug. 25, 2019	Aug. 26, 2018
Earnings Per Share [Abstract]
Net earnings attributable to General Mills		$ 520.6	$ 392.3
Average number of common shares - basic EPS		606.0	598.0
Earnings Per Share, Basic and Diluted [Abstract]
Average number of common shares - diluted EPS		611.5	603.3
Earnings per share - basic		$ 0.86	$ 0.66
Earnings per share - diluted		$ 0.85	$ 0.65
Other Disclosures [Abstract]
Anti-dilutive stock options, restricted stock units and performance share units		10.1	14.3
Stock Options [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Incremental share effect	[1]	3.1	3.6
Restricted Stock, Restricted Stock Units, and Other [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Incremental share effect	[1]	2.4	1.7

[1] (a) Incremental shares from stock options, restricted stock units, and performance share units are computed by the treasury stock method.