Accumulated Other Comprehensive Loss Reclassification out of Accumulated Other Comprehensive Income (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013		Dec. 31, 2012	Dec. 31, 2011
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Tax expense (benefit)									$ 2,135		$ 2,005	$ 1,769
Net of tax	1,122	989	884	798	932	937	802	701	3,793		3,372	2,972
Accumulated Defined Benefit Plans Adjustment [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Actuarial losses									22	[1]
Prior service costs									(1)	[1]
Total before tax									21
Tax expense (benefit)									(7)
Net of tax									$ 14

[1] This accumulated other comprehensive loss component is included in the computation of net periodic pension and retiree health and welfare cost (see Note 13 for additional details).