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, 2016	Feb. 22, 2015	Feb. 28, 2016	Feb. 22, 2015
Earnings Per Share [Abstract]
Net earnings attributable to General Mills		$ 361.7	$ 343.2	$ 1,317.8	$ 1,034.5
Average number of common shares - basic EPS		595.6	598.2	599.1	604.5
Earnings Per Share, Basic and Diluted [Abstract]
Average number of common shares - diluted EPS		608.5	613.8	612.2	620.3
Earnings per share - basic		$ 0.61	$ 0.57	$ 2.2	$ 1.71
Earnings per share - diluted		$ 0.59	$ 0.56	$ 2.15	$ 1.67
Other Disclosures [Abstract]
Anti-dilutive stock options, restricted stock units and performance share units		1.2	2.2	2.7	2.0
Stock Options [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Incremental share effect	[1]	9.6	11.1	9.9	11.5
Restricted Stock, Restricted Stock Units, and Other [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Incremental share effect	[1]	3.3	4.5	3.2	4.3

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