Stockholders' Equity (Schedule of total comprehensive income (loss)) (Details) - USD ($) $ in Millions		3 Months Ended
		Aug. 25, 2019		Aug. 26, 2018
Net earnings attributable to General Mills		$ 520.6		$ 392.3
Net earnings attributable to redeemable and noncontrolling interests		7.9		3.6
Other Comprehensive Income (Loss), Net of Tax:
Foreign currency translation		(3.7)		(106.2)
Other fair value changes:
Hedge derivatives		3.8		7.1
Reclassification to earnings:
Securities		0.0		(2.0)
Hedge derivatives		(0.6)		0.6
Amortization of losses and prior service costs		19.6		21.9
Other comprehensive income (loss), net of tax		19.1		(78.6)
Total comprehensive income (loss) attributable to General Mills		545.4		322.1
General Mills [Member]
Net earnings attributable to General Mills		520.6		392.3
Other Comprehensive Income (Loss), Pretax:
Foreign currency translation		2.7		(96.8)
Other fair value changes:
Hedge derivatives		2.4		7.2
Reclassification to earnings:
Securities	[1]	0.0		(2.6)
Hedge derivatives	[2]	(0.6)		0.5
Amortization of losses and prior service costs	[4]	25.5	[3]	26.9
Other comprehensive income (loss), before tax		30.0		(64.8)
Other Comprehensive Income (Loss), Tax:
Foreign currency translation		0.0		0.0
Other fair value changes:
Hedge derivatives		0.7		(1.0)
Reclassification to earnings:
Securities	[1]	0.0		0.6
Hedge derivatives	[2]	0.0		0.0
Amortization of losses and prior service costs	[4]	(5.9)		(5.0)
Other comprehensive income (loss), tax		(5.2)		(5.4)
Other Comprehensive Income (Loss), Net of Tax:
Foreign currency translation		2.7		(96.8)
Other fair value changes:
Hedge derivatives		3.1		6.2
Reclassification to earnings:
Securities	[1]	0.0		(2.0)
Hedge derivatives	[2]	(0.6)		0.5
Amortization of losses and prior service costs	[4]	19.6		21.9
Other comprehensive income (loss), net of tax		24.8		(70.2)
Total comprehensive income (loss) attributable to General Mills		545.4		322.1
Noncontrolling Interests [Member]
Net earnings attributable to redeemable and noncontrolling interests		3.6		3.1
Other Comprehensive Income (Loss), Net of Tax:
Foreign currency translation		(1.5)		(1.3)
Other fair value changes:
Hedge derivatives		0.0		0.0
Reclassification to earnings:
Securities	[1]	0.0		0.0
Hedge derivatives	[2]	0.0		0.0
Amortization of losses and prior service costs	[4]	0.0		0.0
Other comprehensive income (loss), net of tax		(1.5)		(1.3)
Total comprehensive income (loss) attributable to noncontrolling interests		2.1		1.8
Redeemable Interests [Member]
Net earnings attributable to redeemable and noncontrolling interests		4.3		0.5
Other Comprehensive Income (Loss), Net of Tax:
Foreign currency translation		(4.9)		(8.1)
Other fair value changes:
Hedge derivatives		0.7		0.9
Reclassification to earnings:
Securities	[1]	0.0		0.0
Hedge derivatives	[2]	0.0		0.1
Amortization of losses and prior service costs	[4]	0.0		0.0
Other comprehensive income (loss), net of tax		(4.2)		(7.1)
Total comprehensive income (loss) attributable to redeemable interests		$ 0.1		$ (6.6)

[1] Gain reclassified from AOCI into earnings is reported in interest, net for securities.

[2] Loss (gain) reclassified from AOCI into earnings is reported in interest, net for interest rate swaps and in cost of sales and SG&A expenses for foreign exchange contracts.

[3] (a) Level 3 assets in the fair value hierarchy.

[4] Loss reclassified from AOCI into earnings is reported in benefit plan non-service income.