Pension and Postretirement Benefit Plans (Narratives) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended			9 Months Ended
	Sep. 30, 2014	Dec. 31, 2013	Jun. 30, 2011 LimitedPartner	Sep. 30, 2014 Qualified and Non-qualified Pension Benefits	Sep. 30, 2014 Postretirement Benefits
Benefit Plan Information
Company contributions year to date				$ 107	$ 5
Estimated pension and postretirement employer contributions in current fiscal year	200
Projected benefit obligation (PBO) term vested 2014 liability reduction estimate	270
Pension benefit obligation (PBO) term vested liability reduction as percent of term vested eligible	34.00%
Pension benefit obligation (PBO) term vested liability reduction as percent of overall U.S. pension PBO liability	2.00%
Pension expense impact to income statement in 2014 from Lump Sum Payout	$ 0
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%