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. 25, 2018	Feb. 26, 2017		Feb. 25, 2018		Feb. 26, 2017
Earnings Per Share [Abstract]
Net earnings attributable to General Mills		$ 941.4	$ 357.8		$ 1,776.6		$ 1,248.6
Average number of common shares - basic EPS		572.5	580.7		573.4		589.8
Earnings Per Share, Basic and Diluted [Abstract]
Average number of common shares - diluted EPS		582.7	591.4		583.2		601.1
Earnings per share - basic		$ 1.64	$ 0.62		$ 3.1		$ 2.12
Earnings per share - diluted		$ 1.62	$ 0.61		$ 3.05		$ 2.08
Other Disclosures [Abstract]
Anti-dilutive stock options, restricted stock units and performance share units		5.2	2.4		6.8		2.2
Stock Options [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Incremental share effect	[1]	7.9	7.8		7.7		8.5
Restricted Stock, Restricted Stock Units, and Other [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Incremental share effect		2.3	2.9	[1]	2.1	[1]	2.8	[1]

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