Stockholders' Equity (Schedule of total comprehensive income (loss)) (Details) - USD ($) $ in Millions		3 Months Ended		9 Months Ended		12 Months Ended
		Feb. 25, 2018	Feb. 26, 2017	Feb. 25, 2018	Feb. 26, 2017	May 28, 2017
Net earnings attributable to General Mills		$ 941.4	$ 357.8	$ 1,776.6	$ 1,248.6
Net earnings attributable to redeemable and noncontrolling interests		11.1	12.4	28.3	36.9
Other Comprehensive Income (Loss), Net of Tax:
Foreign currency translation		23.5	113.7	43.0	88.4
Other fair value changes:
Securities		0.6	0.5	1.4	0.8
Hedge derivatives		(6.7)	(4.9)	(15.6)	42.4
Reclassification to earnings:
Hedge derivatives		2.8	(8.7)	3.4	(19.3)
Amortization of losses and prior service costs		30.7	29.9	86.4	92.3
Other comprehensive income (loss), net of tax		50.9	130.5	118.6	204.6
Total comprehensive income (loss) attributable to General Mills		962.7	484.3	1,798.0	1,510.4
General Mills [Member]
Net earnings attributable to General Mills		941.4	357.8	1,776.6	1,248.6
Other Comprehensive Income (Loss), Pretax:
Foreign currency translation		(6.9)	109.0	(55.5)	146.0
Other fair value changes:
Securities		0.8	0.7	2.1	1.2
Hedge derivatives		(7.2)	(6.2)	(19.4)	52.5
Reclassification to earnings:
Hedge derivatives	[1]	3.9	(9.8)	7.2	(18.4)
Amortization of losses and prior service costs	[2]	45.1	48.0	132.7	148.8
Other comprehensive income (loss), before tax		35.7	141.7	67.1	330.1
Other Comprehensive Income (Loss), Tax:
Foreign currency translation		0.0	0.0	0.0	0.0
Other fair value changes:
Securities		(0.2)	(0.2)	(0.7)	(0.4)
Hedge derivatives		1.2	1.3	3.9	(12.8)
Reclassification to earnings:
Hedge derivatives	[1]	(1.0)	1.8	(2.6)	1.4
Amortization of losses and prior service costs	[2]	(14.4)	(18.1)	(46.3)	(56.5)
Other comprehensive income (loss), tax		(14.4)	(15.2)	(45.7)	(68.3)
Other Comprehensive Income (Loss), Net of Tax:
Foreign currency translation		(6.9)	109.0	(55.5)	146.0
Other fair value changes:
Securities		0.6	0.5	1.4	0.8
Hedge derivatives		(6.0)	(4.9)	(15.5)	39.7
Reclassification to earnings:
Hedge derivatives	[1]	2.9	(8.0)	4.6	(17.0)
Amortization of losses and prior service costs	[2]	30.7	29.9	86.4	92.3
Other comprehensive income (loss), net of tax		21.3	126.5	21.4	261.8
Total comprehensive income (loss) attributable to General Mills		962.7	484.3	1,798.0	1,510.4
Noncontrolling Interests [Member]
Net earnings attributable to redeemable and noncontrolling interests		2.8	2.9	8.8	10.7
Other Comprehensive Income (Loss), Net of Tax:
Foreign currency translation		10.3	(0.5)	32.4	(15.7)
Other fair value changes:
Securities		0.0	0.0	0.0	0.0
Hedge derivatives		0.0	0.0	0.0	0.0
Reclassification to earnings:
Hedge derivatives	[1]	0.0	0.0	0.0	0.0
Amortization of losses and prior service costs	[2]	0.0	0.0	0.0	0.0
Other comprehensive income (loss), net of tax		10.3	(0.5)	32.4	(15.7)
Total comprehensive income (loss) attributable to noncontrolling interests		13.1	2.4	41.2	(5.0)
Redeemable Interests [Member]
Net earnings attributable to redeemable and noncontrolling interests		8.3	9.5	19.5	26.2
Other Comprehensive Income (Loss), Net of Tax:
Foreign currency translation		20.1	5.2	66.1	(41.9)
Other fair value changes:
Securities		0.0	0.0	0.0	0.0
Hedge derivatives		(0.7)	0.0	(0.1)	2.7
Reclassification to earnings:
Hedge derivatives	[1]	(0.1)	(0.7)	(1.2)	(2.3)
Amortization of losses and prior service costs	[2]	0.0	0.0	0.0	0.0
Other comprehensive income (loss), net of tax		19.3	4.5	64.8	(41.5)
Total comprehensive income (loss) attributable to redeemable interests		$ 27.6	$ 14.0	$ 84.3	$ (15.3)	$ 17.2

[1] (Gain) loss reclassified from AOCI into earnings is reported in interest, net for interest rate swaps and in cost of sales and selling, general, and administrative (SG&A) expenses for foreign exchange contracts.

[2] Loss reclassified from AOCI into earnings is reported in SG&A expenses.