Stockholders' Equity (Schedule of total comprehensive income (loss)) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Nov. 29, 2020	Nov. 24, 2019	Nov. 29, 2020	Nov. 24, 2019
Net earnings attributable to General Mills	$ 688.4	$ 580.8	$ 1,327.3	$ 1,101.4
Net earnings attributable to redeemable and noncontrolling interests	7.5	10.6	15.0	18.5
Other Comprehensive Income (Loss), Net of Tax:
Foreign currency translation	23.7	(2.8)	89.9	(6.5)
Other fair value changes:
Hedge derivatives	1.9	(12.8)	(10.2)	(9.0)
Reclassification to earnings:
Hedge derivatives	1.0	0.2	(0.7)	(0.4)
Amortization of losses and prior service costs	19.8	19.6	39.3	39.2
Other comprehensive income (loss), net of tax	46.4	4.2	118.3	23.3
Total comprehensive income (loss) attributable to General Mills	729.5	591.6	1,374.1	1,137.0
General Mills [Member]
Net earnings attributable to General Mills	688.4	580.8	1,327.3	1,101.4
Other comprehensive income (loss):
Foreign currency translation	14.5	1.7	(33.6)	4.4
Other fair value changes:
Hedge derivatives	1.9	(11.6)	(13.6)	(9.2)
Reclassification to earnings:
Hedge derivatives	2.0	0.4	(0.1)	(0.2)
Amortization of losses and prior service costs	25.8	25.5	51.1	51.0
Other comprehensive income (loss):	44.2	16.0	3.8	46.0
Other comprehensive income (loss):
Foreign currency translation	3.8	0.0	51.6	0.0
Other fair value changes:
Hedge derivatives	(0.2)	0.9	3.5	1.6
Reclassification to earnings:
Hedge derivatives	(0.7)	(0.2)	(0.3)	(0.2)
Amortization of losses and prior service costs (b)	(6.0)	(5.9)	(11.8)	(11.8)
Other comprehensive income (loss), tax	(3.1)	(5.2)	43.0	(10.4)
Other Comprehensive Income (Loss), Net of Tax:
Foreign currency translation	18.3	1.7	18.0	4.4
Other fair value changes:
Hedge derivatives	1.7	(10.7)	(10.1)	(7.6)
Reclassification to earnings:
Hedge derivatives	1.3	0.2	(0.4)	(0.4)
Amortization of losses and prior service costs	19.8	19.6	39.3	39.2
Other comprehensive income (loss), net of tax	41.1	10.8	46.8	35.6
Total comprehensive income (loss) attributable to General Mills	729.5	591.6	1,374.1	1,137.0
Noncontrolling Interests [Member]
Net earnings attributable to redeemable and noncontrolling interests	2.7	4.9	2.8	8.5
Other Comprehensive Income (Loss), Net of Tax:
Foreign currency translation	2.0	(3.3)	25.3	(4.8)
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 income (loss), net of tax	2.0	(3.3)	25.3	(4.8)
Total comprehensive income (loss) attributable to noncontrolling interests	4.7	1.6	28.1	3.7
Redeemable Interests [Member]
Net earnings attributable to redeemable and noncontrolling interests	4.8	5.7	12.2	10.0
Other Comprehensive Income (Loss), Net of Tax:
Foreign currency translation	3.4	(1.2)	46.6	(6.1)
Other fair value changes:
Hedge derivatives	0.2	(2.1)	(0.1)	(1.4)
Reclassification to earnings:
Hedge derivatives	(0.3)	0.0	(0.3)	0.0
Amortization of losses and prior service costs	0.0	0.0	0.0	0.0
Other comprehensive income (loss), net of tax	3.3	(3.3)	46.2	(7.5)
Total comprehensive income (loss) attributable to redeemable interests	$ 8.1	$ 2.4	$ 58.4	$ 2.5