Accumulated Other Comprehensive Income/(Loss) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended	12 Months Ended
	Sep. 30, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Pension and other postretirement benefits
Total AOCI ending balance		$ (20,032)	$ (18,230)
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Noncontrolling Interest [Abstract]
Cash Flow Hedge Gain (Loss) to be Reclassified within Twelve Months		(145)
Parent Company [Member]
Foreign currency transaction
Beginning balance		(1,746)	(1,245)	(1,386)
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Gain (Loss), before Reclassification and Tax		(702)	(665)	156
Net gain/(loss) on foreign currency translation, tax		53	(53)	0
Net gain/(loss) on foreign currency translation		(755)	(612)	156
Reclassifications to net income	(103)	153	111	(15)
Other comprehensive income/(loss), net of tax		(602)	(501)	141
Ending balance		(2,348)	(1,746)	(1,245)
Derivative instruments
Beginning balance		40	(175)	(181)
Derivative Instruments, Gain (Loss) Recognized in Other Comprehensive Income (Loss), Effective Portion, Net		(271)	317	(371)
Net gain/(loss) on derivative instruments, tax		(96)	141	(115)
Net gain/(loss) on derivative instruments		(175)	176	(256)
Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net		(78)	80	377
Reclassifications to net income, tax		(71)	41	115
Reclassifications to net income		(7)	39	262
Other comprehensive income/(loss), net of tax		(182)	215	6
Ending balance		(142)	40	(175)
Pension and other postretirement benefits
Beginning balance		(16,524)	(21,438)	(17,170)
Other Comprehensive (Income) Loss, Pension and Other Postretirement Benefit Plans, Net Prior Service Cost (Credit) Arising During Period, before Tax		(11)	2	(32)
Prior service cost arising during the period, tax		(2)	0	(1)
Prior service cost arising during the period		(9)	2	(31)
Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Net Unamortized Gain (Loss) Arising During Period, before Tax		(3,321)	5,404	(6,931)
Net gain/(loss) arising during the period, tax		(1,088)	1,883	(2,238)
Net gain/(loss) arising during the period		(2,233)	3,521	(4,693)
Defined Benefit Plan, Amortization of Prior Service Cost (Credit)		(19)	(43)	(253)
Defined Benefit Plan, Amortization of (Gains)/Losses		891	1,499	966
Defined Benefit Plan, Recognized Net (Gain)/Loss Due to Curtailments		0	(2)	(11)
Defined Benefit Plan, Recognized Net (Gain)/Loss Due to Settlements		19	599	250
Other Comprehensive Income Loss Reclassification Adjustment From AOCI Pension And Other Postretirement Benefit Plans Tax (excluding gains and losses arising during period)		259	632	304
Amortization of (gain)/loss included in net income		632	1,421	648
Translation impact on non-U.S. plans		592	(30)	(192)
Other comprehensive income/(loss), net of tax		(1,018)	4,914	(4,268)
Ending balance		(17,542)	(16,524)	(21,438)
Total AOCI ending balance		$ (20,032)	$ (18,230)	$ (22,858)