Significant Accounting Policies (Details 2) (USD $) In Millions, unless otherwise specified	3 Months Ended	9 Months Ended
Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013	Dec. 31, 2013
Significant Accounting Policies
Research, development and related expenses	$ 434	$ 420	$ 1,334	$ 1,277
Deferred tax assets valuation allowance	$ 30		$ 30		$ 23

The aggregate costs incurred during an accounting period to research and develop new products/technologies when the technological feasibility has not been reached, and related expenses, which primarily include technical support provided by 3M to customers who are using existing 3M products; internally developed patent costs, which include costs and fees incurred to prepare, file, secure and maintain patents; and amortization of acquired patents.

No definition available.

Name:	mmm_ResearchDevelopmentAndRelatedExpenses
Namespace Prefix:	mmm_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration