Changes in Accumulated Other Comprehensive Losses (Details) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015		Sep. 30, 2014
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance at January 1	[1]			$ (4,859)
Components of Other Comprehensive Income (Loss):
Before Reclassifications	[1]			(44)
Reclassifications	[1],[2]			354
Other Comprehensive Gain, Net of Tax		$ 102	$ 59	310	[1]	$ 141
Balance at September 30	[1]	(4,549)		(4,549)
Income tax expense		727	$ 3,236	1,787		$ 9,980
Currency Translation Adjustment [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance at January 1	[1]			(96)
Components of Other Comprehensive Income (Loss):
Before Reclassifications	[1]			(35)
Reclassifications	[1],[2]			0
Other Comprehensive Gain, Net of Tax	[1]			(35)
Balance at September 30	[1]	(131)		(131)
Unrealized Holding Gains (Losses) on Securities [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance at January 1	[1]			(8)
Components of Other Comprehensive Income (Loss):
Before Reclassifications	[1]			(24)
Reclassifications	[1],[2]			0
Other Comprehensive Gain, Net of Tax	[1]			(24)
Balance at September 30	[1]	(32)		(32)
Derivatives [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance at January 1	[1]			(2)
Components of Other Comprehensive Income (Loss):
Before Reclassifications	[1]			0
Reclassifications	[1],[2]			0
Other Comprehensive Gain, Net of Tax	[1]			0
Balance at September 30	[1]	(2)		(2)
Defined Benefit Plans [Member]
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Balance at January 1	[1]			(4,753)
Components of Other Comprehensive Income (Loss):
Before Reclassifications	[1]			15
Reclassifications	[1],[2]			354
Other Comprehensive Gain, Net of Tax	[1]			369
Balance at September 30	[1]	$ (4,384)		(4,384)
Defined Benefit Plans [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member]
Components of Other Comprehensive Income (Loss):
Employee benefits reclassification component, included in employee benefit costs				567
Income tax expense				$ 213

[1] All amounts are net of tax.

[2] Refer to Note 10, Employee Benefits for reclassified components totaling $567 million that are included in employee benefit costs for the nine months ending September 30, 2015. Related income taxes for the same period, totaling $213 million, are reflected in Income Tax Expense on the Consolidated Statement of Income. All other reclassified amounts were insignificant.