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Marketable Securities and Held-to-Maturity Debt Securities - Held-to-Maturity Debt Securities (Details) - USD ($) | Sep. 30, 2020 | Dec. 31, 2019
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Held-to-Maturity Debt Securities |  |
Held-to-maturity debt security | $ 0 |
Third lien senior secured notes subject to in-substance |  |
Held-to-Maturity Debt Securities |  |
Held-to-maturity debt security |  | $ 500,000,000

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- Definition Amount of restricted investment in debt security measured at amortized cost (held-to-maturity). + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 860 -SubTopic 30 -Section 50 -Paragraph 1A -Subparagraph (b)(1)(i) -URI http://asc.fasb.org/extlink&oid=109249958&loc=SL6224234-111729 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 946 -SubTopic 10 -Section S99 -Paragraph 3 -Subparagraph (SX 210.6-03(f)) -URI http://asc.fasb.org/extlink&oid=120401367&loc=d3e600178-122990 + Details
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Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

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- References No definition available. + Details
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Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

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- Details
Name: | us-gaap_DebtInstrumentAxis=mmm_ThirdLienSeniorSecuredNotesRelatedToInsubstanceDefeasanceMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |