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

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

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 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_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_TwoPointEightSevenFiveFixedRateNotesMember
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_LongtermDebtTypeAxis=gis_LongTermDebtAgreementsContainingRestrictiveCovenantsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel2Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Debt (Narrative) (Details) € in Millions, $ in Millions	3 Months Ended					6 Months Ended
Debt (Narrative) (Details) € in Millions, $ in Millions	Nov. 29, 2020 EUR (€)	Aug. 30, 2020 EUR (€)	May 31, 2020 USD ($)	Feb. 23, 2020 EUR (€)	Nov. 24, 2019 USD ($)	Nov. 29, 2020 USD ($)	Nov. 24, 2019 USD ($)
Debt Instrument [Line Items]
Long-term debt, carrying value \| $						$ 13,838.2
Issuance of long-term debt \| $						971.3	$ 0.0
Repayment of long-term debt \| $						$ 555.0	$ 509.3
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%
Debt Instrument, Maturity Date	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% 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%
Debt Instrument, 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
Fixed interest rate percentage			2.875%
Debt Instrument, 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%
Debt Instrument, 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%
Debt Instrument, Maturity Date				Nov. 16, 2020
Floating Rate Notes [Member]
Debt Instrument [Line Items]
Repayment of long-term debt				€ 500.0
2.2% Fixed Rate Note [Member]
Debt Instrument [Line Items]
Repayment of long-term debt \| $					$ 500.0
Fixed interest rate percentage					2.20%		2.20%
Long-term Debt Agreements Containing Restrictive Covenants [Member]
Debt Instrument [Line Items]
Covenant compliance						We were in compliance with all credit facility covenants as of November 29, 2020
Fair Value Inputs Level 2 [Member]
Debt Instrument [Line Items]
Long-term debt, fair value \| $						$ 15,421.1