The amount of cash outflow related to a debt exchange participation incentive.

No definition available.

Name:	gis_DebtExchangeParticipationIncentiveCashPayment
Namespace Prefix:	gis_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Represents the minimum fixed charge coverage ratio required to be maintained under certain credit facilities.

+ References

No definition available.

+ Details

Name:	gis_DebtInstrumentCovenantMinimumFixedChargeCoverageRatio
Namespace Prefix:	gis_
Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	instant

- Definition

Principle amount of notes exchanged for new notes and accounted for as a debt modification.

+ References

No definition available.

+ Details

Name:	gis_ModificationOfDebt
Namespace Prefix:	gis_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Amount of unrealized gain (loss), before taxes, related to the increase (decrease) in fair value of interest rate derivatives designated as cash flow hedging instruments, which was recorded in accumulated other comprehensive income to the extent that the cash flow hedge was determined to be effective.

+ References

No definition available.

+ Details

Name:	gis_UnrealizedGainLossOnInterestRateCashFlowHedgesPreTaxAccumulatedOtherComprehensiveIncome1
Namespace Prefix:	gis_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

States whether the entity was in compliance with the debt covenants throughout the reporting period, and describes facts and circumstances of any compliance failure.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 470
-Section 50
-Paragraph 3
-Subparagraph (g)
-URI http://asc.fasb.org/extlink&oid=75038535&loc=d3e64711-112823

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(22))
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

+ Details

Name:	us-gaap_DebtInstrumentCovenantCompliance
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22(a)(1))
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

+ Details

Name:	us-gaap_DebtInstrumentInterestRateStatedPercentage
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

Name:	us-gaap_DebtInstrumentLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Date when the debt instrument is scheduled to be fully repaid, in CCYY-MM-DD format.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22(a)(2))
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (bbb)(2)
-URI http://asc.fasb.org/extlink&oid=117815213&loc=d3e19207-110258

+ Details

Name:	us-gaap_DebtInstrumentMaturityDate
Namespace Prefix:	us-gaap_
Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

- Definition

The estimated net amount of unrealized gains or losses on interest rate cash flow hedges as of the balance sheet date expected to be reclassified to earnings within the next twelve months.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 30
-Section 50
-Paragraph 1
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=121549185&loc=d3e80748-113994

+ Details

Name:	us-gaap_InterestRateCashFlowHedgeGainLossToBeReclassifiedDuringNext12MonthsNet
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Description of the terms of a credit facility arrangement. Terms typically include interest rate, collateral required, guarantees required, repayment requirements, and restrictions on use of assets and activities of the entity.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.19(b),22(b))
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

+ Details

Name:	us-gaap_LineOfCreditFacilityDescription
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.19(b),22(b))
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

+ Details

Name:	us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Fair value portion of contractual obligation to pay money on demand or on fixed or determinable dates.

+ References

No definition available.

+ Details

Name:	us-gaap_LoansPayableFairValueDisclosure
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of long-term debt and lease obligation, including portion classified as current.

+ References

No definition available.

+ Details

Name:	us-gaap_LongTermDebtAndCapitalLeaseObligationsIncludingCurrentMaturities
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The cash inflow from a debt initially having maturity due after one year or beyond the operating cycle, if longer.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 14
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=121586364&loc=d3e3255-108585

+ Details

Name:	us-gaap_ProceedsFromIssuanceOfLongTermDebt
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The cash inflow from a borrowing having initial term of repayment within one year or the normal operating cycle, if longer.

+ References

+ Details

Name:	us-gaap_ProceedsFromShortTermDebt
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The cash outflow for debt initially having maturity due after one year or beyond the normal operating cycle, if longer.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 15
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=121586364&loc=d3e3291-108585

+ Details

Name:	us-gaap_RepaymentsOfLongTermDebt
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Details

Name:	us-gaap_CreditFacilityAxis=us-gaap_LineOfCreditMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_CreditFacilityAxis=gis_LineOfCreditExpiringApril2026Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_CreditFacilityAxis=gis_LineOfCreditExpiringSeptember2022Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_CreditFacilityAxis=gis_LineOfCreditExpiringMay2022Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=gis_TwoPointTwoZeroZeroFixedRateNotesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=gis_FloatingRateNotesDue16April2021Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=us-gaap_MediumTermNotesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RangeAxis=srt_MinimumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RangeAxis=srt_MaximumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=gis_NotesPreviouslyIssuedMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=gis_ThreePercentFixedRateNotesDueFebruary12051Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=gis_ZeroPointZeroZeroZeroFixedRateNotes3Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=gis_ZeroPointZeroZeroFixedRateNotes1Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=gis_ZeroPointZeroZeroZeroFixedRateNotes2Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=gis_TwopointonezerozerofixedratenotesmemberMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=gis_TwoPointEightSevenFiveFixedRateNotesMemberMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=gis_ZeroPointFourFiveFixedRateNotesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=gis_ZeroPointZeroZeroFixedRateNotesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=gis_FloatingRateNotesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=gis_TwoPointTwoPercentFixedRateNoteMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_SubsequentEventTypeAxis=us-gaap_SubsequentEventMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=gis_CertainLongTermDebtAgreementsContainingRestrictiveCovenantsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=gis_TwoTwoPercentNotesDueJune2021Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=gis_ThreeTwoPercentNotesDueApril2021Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Debt (Narrative) (Details) € in Millions, $ in Millions		3 Months Ended							12 Months Ended
Debt (Narrative) (Details) € in Millions, $ in Millions	Jun. 24, 2021 EUR (€)	May 30, 2021 USD ($)	Feb. 28, 2021 USD ($)	Nov. 29, 2020 USD ($)	Nov. 29, 2020 EUR (€)	Aug. 30, 2020 EUR (€)	May 31, 2020 USD ($)	Feb. 23, 2020 EUR (€)	May 30, 2021 USD ($)	May 31, 2020 USD ($)	May 26, 2019 USD ($)
Debt Instrument [Line Items]
Long-term debt, fair value		$ 13,194.4							$ 13,194.4
Interest Rate Cash Flow Hedge Gain (Loss) to be Reclassified During Next 12 Months, Net		4.8							4.8
Long-term debt, carrying value		12,250.7					$ 13,260.5		12,250.7	$ 13,260.5
Issuance of long-term debt									1,576.5	1,638.1	$ 339.1
Repayment of long-term debt									2,609.0	1,396.7	1,493.8
Facility Amount		3,500.0							3,500.0
Debt exchange participation incentive cash payment			$ 201.4						201.4	0.0	$ 0.0
Pre-tax hedge gain (loss) in AOCI		(26.3)							(26.3)
Committed Credit Facilities [Member]
Debt Instrument [Line Items]
Facility Amount		$ 2,900.0							$ 2,900.0
Minimum fixed charge coverage ratio		2.5							2.5
Line Of Credit Expiring April 2026 [Member]
Debt Instrument [Line Items]
Facility Amount		$ 2,700.0							$ 2,700.0
Line of Credit Facility, Description		fee-paid committed credit facility that is scheduled to expire in April 2026
Line Of Credit Expiring September 2022 [Member]
Debt Instrument [Line Items]
Facility Amount		$ 200.0							200.0
Line Of Credit Expiring May 2022 [Member]
Debt Instrument [Line Items]
Facility Amount		$ 2,700.0							$ 2,700.0
2.20% Fixed Rate Note [Member]
Debt Instrument [Line Items]
Repayment of long-term debt				$ 500.0
Fixed interest rate percentage				2.20%	2.20%
Floating-rate notes due April 16, 2021 [Member]
Debt Instrument [Line Items]
Maturity date									Apr. 16, 2021
Medium-term Notes [Member] \| Minimum [Member]
Debt Instrument [Line Items]
Fixed interest rate percentage		0.56%							0.56%
Maturity date									May 28, 2023
Medium-term Notes [Member] \| Maximum [Member]
Debt Instrument [Line Items]
Fixed interest rate percentage		6.41%							6.41%
Notes previously issued [Member]
Debt Instrument [Line Items]
Modification of Debt			$ 603.9
Notes previously issued [Member] \| Minimum [Member]
Debt Instrument [Line Items]
Fixed interest rate percentage			4.15%
Notes previously issued [Member] \| Maximum [Member]
Debt Instrument [Line Items]
Fixed interest rate percentage			5.40%
3.0 percent fixed-rate notes due February 1, 2051 [Member]
Debt Instrument [Line Items]
Issuance of long-term debt			$ 605.2
Fixed interest rate percentage			3.00%
Maturity date			Feb. 01, 2051
0.00% Fixed Rate Notes Due Nov. 16 2021 [Member]
Debt Instrument [Line Items]
Issuance of long-term debt \| €					€ 500.0
Fixed interest rate percentage				0.00%	0.00%
Maturity date				Nov. 16, 2021	Nov. 16, 2021
0.00% Fixed Rate Notes [Member]
Debt Instrument [Line Items]
Repayment of long-term debt \| €					€ 200.0			€ 300.0
Fixed interest rate percentage				0.00%	0.00%			0.00%
0.00% Fixed Rate Notes Due Aug.21, 2021 [Member]
Debt Instrument [Line Items]
Issuance of long-term debt \| €						€ 500.0
Fixed interest rate percentage						0.00%
Maturity date						Aug. 21, 2021
2.1 % Fixed Rate Notes [Member]
Debt Instrument [Line Items]
Repayment of long-term debt \| €						€ 500.0
Fixed interest rate percentage						2.10%
2.875% Fixed Rate Notes Due April 15, 2030 [Member]
Debt Instrument [Line Items]
Issuance of long-term debt							$ 750.0			$ 750.0
Fixed interest rate percentage							2.875%			2.875%
Maturity date							Apr. 15, 2030
0.45% Fixed Rate Notes Due Jan. 15 2026 [Member]
Debt Instrument [Line Items]
Issuance of long-term debt \| €								€ 600.0
Fixed interest rate percentage								0.45%
Maturity date								Jan. 15, 2026
0.00% Fixed Rate Notes Due Nov. 16 2020 [Member]
Debt Instrument [Line Items]
Issuance of long-term debt \| €								€ 200.0
Fixed interest rate percentage								0.00%
Maturity date								Nov. 16, 2020
Floating Rate Notes [Member]
Debt Instrument [Line Items]
Repayment of long-term debt		$ 850.0						€ 500.0
2.2% Fixed Rate Note [Member] \| Subsequent Event [Member]
Debt Instrument [Line Items]
Fixed interest rate percentage	2.20%
Maturity date	Nov. 29, 2021
Proceeds from Short-term Debt \| €	€ 50.0
Certain Long Term Debt Agreements Containing Restrictive Covenants [Member]
Debt Instrument [Line Items]
Debt Instrument, Covenant Compliance									As of May 30, 2021, we were in compliance with all of these covenants.
Euro-denominated 2.2% notes due June 24, 2021 [Member]
Debt Instrument [Line Items]
Fixed interest rate percentage		2.20%							2.20%
Maturity date									Jun. 24, 2021
Euro-denominated 2.2% notes due June 24, 2021 [Member] \| Subsequent Event [Member]
Debt Instrument [Line Items]
Repayment of long-term debt \| €	€ 200.0
Fixed interest rate percentage	2.20%
Maturity date	Jun. 24, 2021
3.2% notes due April 2021 [Member]
Debt Instrument [Line Items]
Repayment of long-term debt		$ 600.0
Fixed interest rate percentage		3.20%							3.20%
Maturity date									Apr. 16, 2021