Comprehensive Income Reclassifications out of Accumulated Other Comprehensive Income (Details) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2016	Mar. 31, 2015
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Total before tax		$ (1,258)	$ (1,672)
Tax (expense)/benefit		474	627
Net of tax		(784)	(1,045)
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	[1],[2]	0	(1)
Prior service credits	[1],[2]	0	1
Total before tax	[1]	0	0
Tax (expense)/benefit	[1]	0	0
Net of tax	[1]	$ 0	$ 0

[1] Amounts in parenthesis indicate debits to the income statement.

[2] This accumulated other comprehensive income component is included in the computation of net periodic pension and retiree health and welfare cost (see Note 8 for additional details).