Stockholders' Equity (Schedule of total comprehensive income (loss)) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Nov. 28, 2021	Nov. 29, 2020	Nov. 28, 2021	Nov. 29, 2020
Other Comprehensive Income (Loss), Net of Tax:
Net earnings attributable to General Mills	$ 597.2	$ 688.4	$ 1,224.2	$ 1,327.3
Net earnings attributable to redeemable and noncontrolling interests	11.2	7.5	22.4	15.0
Foreign currency translation	(38.5)	23.7	(62.4)	89.9
Other fair value changes:
Hedge derivatives	18.7	1.9	20.4	(10.2)
Reclassification to earnings:
Hedge derivatives	(6.4)	1.0	4.2	(0.7)
Amortization of losses and prior service costs	22.8	19.8	31.2	39.3
Other comprehensive (loss) income, net of tax	(3.4)	46.4	(6.6)	118.3
Total comprehensive income (loss) attributable to General Mills	630.8	729.5	1,289.3	1,374.1
General Mills [Member]
Other comprehensive income (loss) Pretax:
Foreign currency translation	(29.0)	14.5	(40.9)	(33.6)
Other fair value changes:
Hedge derivatives	29.1	1.9	31.9	(13.6)
Reclassification to earnings:
Hedge derivatives	(12.1)	2.0	(0.1)	(0.1)
Amortization of losses and prior service costs	29.2	25.8	40.0	51.1
Other comprehensive income (loss Pretax):	17.2	44.2	30.9	3.8
Other comprehensive income (loss) Tax:
Foreign currency translation	27.8	3.8	(50.5)	51.6
Other fair value changes:
Hedge derivatives	(11.0)	0.2	(12.0)	3.5
Reclassification to earnings:
Hedge derivatives	6.0	(0.7)	4.5	(0.3)
Amortization of losses and prior service costs (b)	(6.4)	(6.0)	(8.8)	(11.8)
Other comprehensive income (loss), tax	16.4	(3.1)	34.2	43.0
Other Comprehensive Income (Loss), Net of Tax:
Net earnings attributable to General Mills	597.2	688.4	1,224.2	1,327.3
Foreign currency translation	(1.2)	18.3	9.6	18.0
Other fair value changes:
Hedge derivatives	18.1	1.7	19.9	(10.1)
Reclassification to earnings:
Hedge derivatives	(6.1)	1.3	4.4	(0.4)
Amortization of losses and prior service costs	22.8	19.8	31.2	39.3
Other comprehensive (loss) income, net of tax	33.6	41.1	65.1	46.8
Total comprehensive income (loss) attributable to General Mills	630.8	729.5	1,289.3	1,374.1
Noncontrolling Interests [Member]
Other Comprehensive Income (Loss), Net of Tax:
Net earnings attributable to redeemable and noncontrolling interests	1.9	2.7	4.9	2.8
Foreign currency translation	(13.8)	2.0	(25.0)	25.3
Other fair value changes:
Hedge derivatives	0.0	0.0	0.0	0.0
Reclassification to earnings:
Hedge derivatives	0.0	0.0	0.0	0.0
Amortization of losses and prior service costs	0.0	0.0	0.0	0.0
Other comprehensive (loss) income, net of tax	(13.8)	2.0	(25.0)	25.3
Total comprehensive income (loss) attributable to noncontrolling interests	(11.9)	4.7	(20.1)	28.1
Redeemable Interest [Member]
Other Comprehensive Income (Loss), Net of Tax:
Net earnings attributable to redeemable and noncontrolling interests	9.3	4.8	17.5	12.2
Foreign currency translation	(23.5)	3.4	(47.0)	46.6
Other fair value changes:
Hedge derivatives	0.6	0.2	0.5	(0.1)
Reclassification to earnings:
Hedge derivatives	(0.3)	(0.3)	0.2	(0.3)
Amortization of losses and prior service costs	0.0	0.0	0.0	0.0
Other comprehensive (loss) income, net of tax	(23.2)	3.3	(46.7)	46.2
Total comprehensive income (loss) attributable to redeemable interests	$ (13.9)	$ 8.1	$ (29.2)	$ 58.4