Pension and Postretirement Benefit Plans (Narratives) (Details) (USD $) In Millions, unless otherwise specified					3 Months Ended
	Dec. 31, 2013	Mar. 31, 2011 LimitedPartner	Mar. 31, 2014 Maximum	Mar. 31, 2014 Minimum	Mar. 31, 2014 Qualified and Non-qualified Pension Benefits	Mar. 31, 2014 Postretirement Benefits
Benefit Plan Information
Company contributions year to date					$ 40	$ 2
Estimated pension and postretirement employer contributions in current fiscal year			$ 200	$ 100
Number of additional limited partners of WG Trading Company, in addition to 3M, who objected and appealed the court's order to the United States Court of Appeals for the Second Circuit		6
Percentage of WG Trading Company holdings in relation to total fair value of the company's total plan assets, high end of range (as a percent)	1.00%