Commitments and Contingencies (Details 3) (USD $) In Millions, except Share data, unless otherwise specified	9 Months Ended
	Sep. 30, 2012 Lawsuits
Commercial Litigation - Cogent Inc. Delaware Court of Chancery
Loss contingencies
Number of Cogent, Inc. shares held by subsidiary shareholders that have asserted appraisal rights	5,800,000
Number of lawsuits filed	3
Commercial Litigation - Ceradyne Inc.
Loss contingencies
Number of purported class actions filed	4
Commercial Litigation - Ceradyne Inc. California Superior Court
Loss contingencies
Number of purported class actions filed	2
Commercial Litigation - Ceradyne Inc. Delaware Chancery Court
Loss contingencies
Number of purported class actions filed	2
Commercial Litigation - Avery Dennison
Loss contingencies
Number of Avery patents for which 3M seeks a declaratory judgment	2
Total number of disputed terms ruled in favor of the company	16
Total number of disputed terms	19
Number of cases Avery has filed motion to join	3
Commercial Litigation - Meda AB
Loss contingencies
The estimated minimum amount the lawsuit seeks to recover	300
Number of new claims filed	3
Number of days trial expected to last	14 days