Stockholders' Equity (Schedule of total comprehensive income) (Details) - USD ($) $ in Millions		3 Months Ended								12 Months Ended
		May 27, 2018	Feb. 25, 2018	Nov. 26, 2017	Aug. 27, 2017	May 28, 2017	Feb. 26, 2017	Nov. 27, 2016	Aug. 28, 2016	May 27, 2018		May 28, 2017		May 29, 2016
Other comprehensive income (loss), net of tax:
Foreign currency translation										$ (37.0)		$ 6.3		$ (108.7)
Net actuarial income (loss)										140.1		197.9		(325.9)
Other fair value changes:
Securities										1.2		0.8		0.1
Hedge derivatives										(50.8)		53.3		16.0
Reclassification to earnings:
Securities										(5.1)		0.0		0.0
Hedge derivatives										17.4		(25.7)		(9.5)
Amortization of losses and prior service costs										117.6		122.5		128.6
Other comprehensive income (loss), net of tax										183.4		355.1		(299.4)
Comprehensive Income:
Net earnings attributable to General Mills		$ 354.4	$ 941.4	$ 430.5	$ 404.7	$ 408.9	$ 357.8	$ 481.8	$ 409.0	2,131.0		1,657.5		1,697.4
Net earnings attributable to redeemable and noncontrolling interests										32.0		43.6		39.4
Total comprehensive income (loss) attributable to General Mills										2,275.9		2,025.2		1,395.9
General Mills [Member]
Other comprehensive income (loss), before tax:
Foreign currency translation										(76.9)		19.5		(107.6)
Net actuarial income (loss)										185.5		307.3		(514.2)
Other fair value chages:
Securities										1.8		1.3		0.2
Hedge derivaties										(64.7)		65.9		16.5
Reclassification to earnings:
Securities	[1]									(6.6)
Hedge derivatives										24.9	[2]	(25.2)	[3]	(13.5)	[4]
Amortization of losses and prior service costs										176.8	[5]	197.2	[6]	206.8	[7]
Other comprehensive income (loss), before tax										240.8		566.0		(411.8)
Other comprehensive income (loss), tax:
Foreign currency translation										0.0		0.0		0.0
Net actuarial income (loss)										(45.4)		(109.4)		188.3
Other fair value changes:
Securities										(0.6)		(0.5)		(0.1)
Hedge derivatives										14.2		(16.1)		(2.2)
Reclassification to earnings:
Securities	[1]									1.5
Hedge derivatives										(6.4)	[2]	2.4	[3]	2.5	[4]
Amortization of losses and prior service costs										(59.2)	[5]	(74.7)	[6]	(78.2)	[7]
Other comprehensive income (loss), tax										(95.9)		(198.3)		110.3
Other comprehensive income (loss), net of tax:
Foreign currency translation										(76.9)		19.5		(107.6)
Net actuarial income (loss)										140.1		197.9		(325.9)
Other fair value changes:
Securities										1.2		0.8		0.1
Hedge derivatives										(50.5)		49.8		14.3
Reclassification to earnings:
Securities	[1]									(5.1)
Hedge derivatives										18.5	[2]	(22.8)	[3]	(11.0)	[4]
Amortization of losses and prior service costs										117.6	[5]	122.5	[6]	128.6	[7]
Other comprehensive income (loss), net of tax										144.9		367.7		(301.5)
Comprehensive Income:
Net earnings attributable to General Mills										2,131.0		1,657.5		1,697.4
Total comprehensive income (loss) attributable to General Mills										2,275.9		2,025.2		1,395.9
Noncontrolling Interests [Member]
Other comprehensive income (loss), net of tax:
Foreign currency translation										13.5		2.5		2.8
Net actuarial income (loss)										0.0		0.0		0.0
Other fair value changes:
Securities										0.0		0.0		0.0
Hedge derivatives										0.0		0.0		0.0
Reclassification to earnings:
Securities	[1]									0.0
Hedge derivatives										0.0	[2]	0.0	[3]	0.0	[4]
Amortization of losses and prior service costs										0.0	[5]	0.0	[6]	0.0	[7]
Other comprehensive income (loss), net of tax										13.5		2.5		2.8
Comprehensive Income:
Net earnings attributable to redeemable and noncontrolling interests										13.4		11.3		8.4
Total comprehensive income (loss) attributable to noncontrolling interests										26.9		13.8		11.2
Redeemable Interest [Member]
Other comprehensive income (loss), net of tax:
Foreign currency translation										26.4		(15.7)		(3.9)
Net actuarial income (loss)										0.0		0.0		0.0
Other fair value changes:
Securities										0.0		0.0		0.0
Hedge derivatives										(0.3)		3.5		1.7
Reclassification to earnings:
Securities	[1]									0.0
Hedge derivatives										(1.1)	[2]	(2.9)	[3]	1.5	[4]
Amortization of losses and prior service costs										0.0	[5]	0.0	[6]	0.0	[7]
Other comprehensive income (loss), net of tax										25.0		(15.1)		(0.7)
Comprehensive Income:
Net earnings attributable to redeemable and noncontrolling interests										18.6		32.3		31.0
Total comprehensive income (loss) attributable to redeemable interests										$ 43.6		$ 17.2		$ 30.3

[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 e xchange contracts.

[3] 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.

[4] (a ) 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.

[5] Loss reclassified from AOCI into earnings is reported in SG&A expense s .

[6] Loss reclassified from AOCI into earnings is reported in SG&A expense s .

[7] Loss reclassified from AOCI into earnings is reported in SG&A expense s .