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. 26, 2017	Feb. 28, 2016	Feb. 26, 2017	Feb. 28, 2016
Earnings Per Share [Abstract]
Net earnings attributable to General Mills		$ 357.8	$ 361.7	$ 1,248.6	$ 1,317.8
Average number of common shares - basic EPS		580.7	595.6	589.8	599.1
Earnings Per Share, Basic and Diluted [Abstract]
Average number of common shares - diluted EPS		591.4	608.5	601.1	612.2
Earnings per share - basic		$ 0.62	$ 0.61	$ 2.12	$ 2.2
Earnings per share - diluted		$ 0.61	$ 0.59	$ 2.08	$ 2.15
Other Disclosures [Abstract]
Anti-dilutive stock options, restricted stock units and performance share units		2.4	1.2	2.2	2.7
Stock Options [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Incremental share effect	[1]	7.8	9.6	8.5	9.9
Restricted Stock, Restricted Stock Units, and Other [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Incremental share effect	[1]	2.9	3.3	2.8	3.2

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