Stockholders' Equity (Schedule of total comprehensive income (loss)) (Details) - USD ($) $ in Millions		3 Months Ended		9 Months Ended		12 Months Ended
		Feb. 28, 2016	Feb. 22, 2015	Feb. 28, 2016	Feb. 22, 2015	May. 31, 2015
Net earnings attributable to General Mills		$ 361.7	$ 343.2	$ 1,317.8	$ 1,034.5
Net earnings (loss) attributable to redeemable and noncontrolling interests		6.0	10.6	28.6	27.1
Other Comprehensive Income (Loss), Net of Tax:
Foreign currency translation		(39.9)	(411.3)	(252.4)	(801.1)
Other fair value changes:
Securities		(0.2)	0.5	(0.2)	0.8
Hedge derivatives		19.0	10.9	29.4	15.5
Reclassification to earnings:
Hedge derivatives	[1]	(3.7)	(0.1)	(3.3)	5.2
Amortization of losses and prior service costs	[2]	31.0	27.8	97.8	80.8
Other comprehensive income (loss), net of tax		6.2	(372.2)	(128.7)	(698.8)
Total comprehensive income (loss) attributable to General Mills		353.8	65.0	1,213.6	537.0
General Mills [Member]
Net earnings attributable to General Mills		361.7	343.2	1,317.8	1,034.5
Other Comprehensive Income (Loss), Pretax:
Foreign currency translation		(50.4)	(319.3)	(223.1)	(601.4)
Other fair value changes:
Securities		(0.3)	0.6	(0.3)	1.2
Hedge derivatives		15.7	20.3	31.0	27.4
Reclassification to earnings:
Hedge derivatives	[1]	(4.7)	(0.8)	(7.0)	4.0
Amortization of losses and prior service costs	[2]	49.7	44.8	157.1	131.1
Other comprehensive income (loss), before tax		10.0	(254.4)	(42.3)	(437.7)
Other Comprehensive Income (Loss), Tax:
Foreign currency translation		0.0	0.0	0.0	0.0
Other fair value changes:
Securities		0.1	(0.1)	0.1	(0.4)
Hedge derivatives		(0.2)	(6.8)	(4.4)	(8.3)
Reclassification to earnings:
Hedge derivatives	[1]	0.9	0.1	1.7	(0.8)
Amortization of losses and prior service costs	[2]	(18.7)	(17.0)	(59.3)	(50.3)
Other comprehensive income (loss), tax		(17.9)	(23.8)	(61.9)	(59.8)
Other Comprehensive Income (Loss), Net of Tax:
Foreign currency translation		(50.4)	(319.3)	(223.1)	(601.4)
Other fair value changes:
Securities		(0.2)	0.5	(0.2)	0.8
Hedge derivatives		15.5	13.5	26.6	19.1
Reclassification to earnings:
Hedge derivatives	[1]	(3.8)	(0.7)	(5.3)	3.2
Amortization of losses and prior service costs	[2]	31.0	27.8	97.8	80.8
Other comprehensive income (loss), net of tax		(7.9)	(278.2)	(104.2)	(497.5)
Total comprehensive income (loss) attributable to General Mills		353.8	65.0	1,213.6	537.0
Noncontrolling Interests [Member]
Net earnings (loss) attributable to redeemable and noncontrolling interests		1.7	2.1	8.2	7.7
Other Comprehensive Income (Loss), Net of Tax:
Foreign currency translation		9.5	(29.2)	(2.7)	(66.8)
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		9.5	(29.2)	(2.7)	(66.8)
Total comprehensive income (loss) attributable to noncontrolling interests		11.2	(27.1)	5.5	(59.1)
Redeemable Interests [Member]
Net earnings (loss) attributable to redeemable and noncontrolling interests		4.3	8.5	20.4	19.4
Other Comprehensive Income (Loss), Net of Tax:
Foreign currency translation		1.0	(62.8)	(26.6)	(132.9)
Other fair value changes:
Securities		0.0	0.0	0.0	0.0
Hedge derivatives		3.5	(2.6)	2.8	(3.6)
Reclassification to earnings:
Hedge derivatives	[1]	0.1	0.6	2.0	2.0
Amortization of losses and prior service costs	[2]	0.0	0.0	0.0	0.0
Other comprehensive income (loss), net of tax		4.6	(64.8)	(21.8)	(134.5)
Total comprehensive income (loss) attributable to redeemable interests		$ 8.9	$ (56.3)	$ (1.4)	$ (115.1)	$ (122.9)

[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.