Pension and Postretirement Benefit Plans - Plan Amount Narrative (Details) $ in Millions	12 Months Ended
Dec. 31, 2020 USD ($) plan country	Dec. 31, 2019 USD ($)
Unfunded Plans
Benefit Plan Information
Maximum amount of certain nonqualified unfunded pension and postretirement benefit plans obligations not included in benefit obligation reconciliation \| $	$ 40	$ 40
Qualified and Non-qualified Pension Benefits
Benefit Plan Information
Company-sponsored retirement plans, minimum number of worldwide plans \| plan	75
Company-sponsored retirement plans, number of countries \| country	28
Qualified and Non-qualified Pension Benefits \| International
Benefit Plan Information
Company-sponsored retirement plans, minimum number of international plans \| plan	70
Company-sponsored retirement plans, number of countries \| country	25

The number of company-sponsored international plans aggregated together for disclosures purposes.

No definition available.

Name:	mmm_DefinedBenefitPlanNumberOfPlansMinimum
Namespace Prefix:	mmm_
Data Type:	xbrli:integerItemType
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Period Type:	instant

- Definition

The number of company-sponsored worldwide plans aggregated together for disclosures purposes.

+ References

No definition available.

+ Details

Name:	mmm_DefinedBenefitPlanNumberOfPlansWorldwideMinimum
Namespace Prefix:	mmm_
Data Type:	xbrli:integerItemType
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Period Type:	instant

- Definition

Maximum amount of certain nonqualified unfunded pension and postretirement benefit plans obligations not included in benefit obligation reconciliation.

+ References

No definition available.

+ Details

Name:	mmm_MaximumAmountOfCertainNonqualifiedUnfundedPensionAndPostretirementBenefitPlansObligationsNotIncludedInBenefitObligationReconciliation
Namespace Prefix:	mmm_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

This element represents the number of countries in which company has company-sponsored plans.

+ References

No definition available.

+ Details

Name:	mmm_NumberOfCountriesInWhichRetirementPlansSponsored
Namespace Prefix:	mmm_
Data Type:	xbrli:integerItemType
Balance Type:	na
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- 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

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- Details

Name:	us-gaap_RetirementPlanFundingStatusAxis=us-gaap_UnfundedPlanMember
Namespace Prefix:
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- Details

Name:	us-gaap_RetirementPlanTypeAxis=us-gaap_PensionPlansDefinedBenefitMember
Namespace Prefix:
Data Type:	na
Balance Type:
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- Details

Name:	us-gaap_RetirementPlanSponsorLocationAxis=us-gaap_ForeignPlanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: