Leases - Operating leases not yet commenced (Details) $ in Millions	Sep. 30, 2019 USD ($)
Leases
Additional operating lease commitments that have not yet commenced	$ 29

The value of the lessee's operating lease which has not yet commenced.

No definition available.

Name:	mmm_LesseeOperatingLeaseLeaseNotYetCommencedAmount
Namespace Prefix:	mmm_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant