Earnings per Share (Schedule of earnings per share) (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions		3 Months Ended
		Aug. 28, 2016	Aug. 30, 2015
Earnings Per Share [Abstract]
Net earnings attributable to General Mills		$ 409.0	$ 426.6
Average number of common shares - basic EPS		600.0	601.7
Earnings Per Share, Basic and Diluted [Abstract]
Average number of common shares - diluted EPS		612.4	615.5
Earnings per share - basic		$ 0.68	$ 0.71
Earnings per share - diluted		$ 0.67	$ 0.69
Other Disclosures [Abstract]
Anti-dilutive stock options, restricted stock units and performance share units		1.2	2.4
Stock Options [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Incremental share effect	[1]	9.5	10.4
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	3.4

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