Significant Accounting Policies - Internal-use Software (Details)	12 Months Ended
Dec. 31, 2020
Minimum
Capitalized internal-use software amortization period (in years)	3 years
Maximum
Capitalized internal-use software amortization period (in years)	7 years

The capitalized internal-use software amortization period.

No definition available.

Name:	mmm_CapitalizedComputerSoftwareAmortizationPeriod
Namespace Prefix:	mmm_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration