Stockholders' Equity (Schedule of total comprehensive income (loss)) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Feb. 27, 2022	Feb. 28, 2021	Feb. 27, 2022	Feb. 28, 2021
Reclassification to earnings:
Foreign currency translation	$ 342.2	$ 0.0	$ 342.2	$ 0.0
Other Comprehensive Income (Loss), Net of Tax:
Net earnings attributable to General Mills	660.3	595.7	1,884.5	1,923.0
Net earnings attributable to redeemable and noncontrolling interests	2.3	8.1	24.7	23.1
Foreign currency translation	(122.5)	12.5	(184.9)	102.4
Other fair value changes:
Hedge derivatives	(30.8)	0.1	(10.4)	(10.1)
Reclassification to earnings:
Amortization of losses and prior service costs	22.3	19.8	53.5	59.1
Hedge derivatives	30.2	5.4	34.4	4.7
Other comprehensive (loss) income, net of tax	241.4	37.8	234.8	156.1
Total comprehensive income (loss) attributable to General Mills	901.7	620.6	2,191.0	1,994.7
General Mills [Member]
Other comprehensive income (loss) Pretax:
Foreign currency translation	(125.7)	(7.8)	(166.6)	(41.4)
Other fair value changes:
Hedge derivatives	(23.9)	2.5	8.0	(11.1)
Reclassification to earnings:
Foreign currency translation	342.2		342.2
Amortization of losses and prior service costs	28.8	25.6	68.8	76.7
Hedge derivatives	23.1	6.8	23.0	6.7
Other comprehensive (loss) income (Pretax)	244.5	27.1	275.4	30.9
Other comprehensive income (loss) Tax:
Foreign currency translation	3.2	6.7	53.7	58.3
Other fair value changes:
Hedge derivatives	(6.9)	(1.5)	(18.9)	2.0
Reclassification to earnings:
Foreign currency translation	0.0		0.0
Amortization of losses and prior service costs (b)	(6.5)	(5.8)	(15.3)	(17.6)
Hedge derivatives	7.1	(1.6)	11.6	(1.9)
Other comprehensive income (loss), tax	(3.1)	(2.2)	31.1	40.8
Other Comprehensive Income (Loss), Net of Tax:
Net earnings attributable to General Mills	660.3	595.7	1,884.5	1,923.0
Foreign currency translation	(122.5)	(1.1)	(112.9)	16.9
Other fair value changes:
Hedge derivatives	(30.8)	1.0	(10.9)	(9.1)
Reclassification to earnings:
Foreign currency translation	342.2		342.2
Amortization of losses and prior service costs	22.3	19.8	53.5	59.1
Hedge derivatives	30.2	5.2	34.6	4.8
Other comprehensive (loss) income, net of tax	241.4	24.9	306.5	71.7
Total comprehensive income (loss) attributable to General Mills	901.7	620.6	2,191.0	1,994.7
Noncontrolling Interests [Member]
Other Comprehensive Income (Loss), Net of Tax:
Net earnings attributable to redeemable and noncontrolling interests	2.3	1.1	7.2	3.9
Foreign currency translation	0.0	2.6	(25.0)	27.9
Other fair value changes:
Hedge derivatives	0.0	0.0	0.0	0.0
Reclassification to earnings:
Amortization of losses and prior service costs	0.0	0.0	0.0	0.0
Hedge derivatives	0.0	0.0	0.0	0.0
Other comprehensive (loss) income, net of tax	0.0	2.6	(25.0)	27.9
Total comprehensive income (loss) attributable to noncontrolling interests	2.3	3.7	(17.8)	31.8
Redeemable Interest [Member]
Other Comprehensive Income (Loss), Net of Tax:
Net earnings attributable to redeemable and noncontrolling interests	0.0	7.0	17.5	19.2
Foreign currency translation	0.0	11.0	(47.0)	57.6
Other fair value changes:
Hedge derivatives	0.0	(0.9)	0.5	(1.0)
Reclassification to earnings:
Amortization of losses and prior service costs	0.0	0.0	0.0	0.0
Hedge derivatives	0.0	0.2	(0.2)	(0.1)
Other comprehensive (loss) income, net of tax	0.0	10.3	(46.7)	56.5
Total comprehensive income (loss) attributable to redeemable interests	$ 0.0	$ 17.3	$ (29.2)	$ 75.7