Stockholders' Equity (Schedule of total comprehensive income (loss)) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		12 Months Ended
	Aug. 26, 2012	Aug. 28, 2011	May 27, 2012
Other Comprehensive Income (Loss) Net [Abstract]
Foreign currency translation adjustments	$ 65.4	$ (0.3)
Other fair value changes:
Securities	0.2	(0.2)
Hedge derivatives	(7.5)	(31.8)
Reclassification to earnings:
Hedge derivatives	3.8	3.1
Amortization of losses and prior service costs	24.7	20.5
Other comprehensive income (loss), net of tax	86.6	(8.7)
Net earnings attributable to General Mills	548.9	405.6
Net earnings attributable to noncontrolling interests	2.5	0.3
Net earnings attributable to redeemable interests	10.7	(1.6)
Total comprehensive income (loss) attributable to General Mills	630.1	401.7
Total comprehensive income (loss) attributable to noncontrolling interests	2.0	(0.2)
Total comprehensive income (loss) attributable to redeemable interests	16.6	(5.9)
General Mills [Member]
Other Comprehensive Income (Loss) Before Tax [Abstract]
Foreign currency translation adjustments pretax	60.3	3.6
Other fair value changes:
Securities	0.3	(0.4)
Hedge derivatives	(8.6)	(52.1)
Reclassification to earnings:
Hedge derivatives	4.5	5.1
Amortization of losses and prior service costs	40.0	32.9
Other Comprehensive Income (Loss), before Tax	96.5	(10.9)
Other Comprehensive Income (Loss) Tax [Abstract]
Foreign currency translation adjustments	0	0
Other fair value changes:
Securities	(0.1)	0.2
Hedge derivatives	1.5	21.2
Reclassification to earnings:
Hedge derivatives	(1.4)	(2.0)
Amortization of losses and prior service costs	(15.3)	(12.4)
Other Comprehensive Income (Loss), Tax	(15.3)	7.0
Other Comprehensive Income (Loss) Net [Abstract]
Foreign currency translation adjustments	60.3	3.6
Other fair value changes:
Securities	0.2	(0.2)
Hedge derivatives	(7.1)	(30.9)
Reclassification to earnings:
Hedge derivatives	3.1	3.1
Amortization of losses and prior service costs	24.7	20.5
Other comprehensive income (loss), net of tax	81.2	(3.9)
Noncontrolling Interests [Member]
Other Comprehensive Income (Loss) Net [Abstract]
Foreign currency translation adjustments	(0.5)	(0.5)
Other fair value changes:
Securities	0	0
Hedge derivatives	0	0
Reclassification to earnings:
Hedge derivatives	0	0
Amortization of losses and prior service costs		0
Other comprehensive income (loss), net of tax	(0.5)	(0.5)
Redeemable Interests [Member]
Other Comprehensive Income (Loss) Net [Abstract]
Foreign currency translation adjustments	5.6	(3.4)
Other fair value changes:
Securities	0	0
Hedge derivatives	(0.4)	(0.9)
Reclassification to earnings:
Hedge derivatives	0.7	0
Amortization of losses and prior service costs	0	0
Other comprehensive income (loss), net of tax	5.9	(4.3)
Total comprehensive income (loss) attributable to redeemable interests	$ 16.6		$ (86.1)