Shareowners' Equity (Accumulated Other Comprehensive Income) (Details) - USD ($) $ in Millions	3 Months Ended		12 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2016
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Accumulated Other Comprehensive Income (Loss) Beginning balance	$ (18,598)
OCI reclass tax	(16)	$ 177
Other comprehensive income, net of tax	1,833	826
Less Other comprehensive income (loss) attributable to noncontrolling interests	(6)	(2)
Accumulated Other Comprehensive Income (Loss) Ending balance	(16,771)	(15,705)	$ (18,598)
Investment Securities
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Accumulated Other Comprehensive Income (Loss) Beginning balance	674	460	460
Other comprehensive income (OCI) before reclassifications - net of deferred taxes	18	159
OCI before reclassification tax	13	81
OCI reclass tax	(36)	40
Reclassification from OCI net of deferred taxes	(69)	60
Other comprehensive income, net of tax	(52)	220
Less Other comprehensive income (loss) attributable to noncontrolling interests	0	0
Accumulated Other Comprehensive Income (Loss) Ending balance	622	680	674
Currency Translation Adjustment
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Accumulated Other Comprehensive Income (Loss) Beginning balance	(6,816)	(5,499)	(5,499)
Other comprehensive income (OCI) before reclassifications - net of deferred taxes	262	115
OCI before reclassification tax	(33)	266
OCI reclass tax	(540)	119
Reclassification from OCI net of deferred taxes	554	(114)
Other comprehensive income, net of tax	815	1
Less Other comprehensive income (loss) attributable to noncontrolling interests	4	3
Accumulated Other Comprehensive Income (Loss) Ending balance	(6,004)	(5,500)	(6,816)
Cash Flow Hedge
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Accumulated Other Comprehensive Income (Loss) Beginning balance	12	(80)	(80)
Other comprehensive income (OCI) before reclassifications - net of deferred taxes	20	(25)
OCI before reclassification tax	5	(8)
OCI reclass tax	1	5
Reclassification from OCI net of deferred taxes	0	79
Other comprehensive income, net of tax	20	55
Less Other comprehensive income (loss) attributable to noncontrolling interests	0	0
Accumulated Other Comprehensive Income (Loss) Ending balance	32	(26)	12
Benefit Plans [Member]
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Accumulated Other Comprehensive Income (Loss) Beginning balance	(12,469)	(11,410)	(11,410)
Other comprehensive income, net of tax	1,049	550
Prior Service credit (costs)- net of deferred taxes	0	23
Net actuarial gain (loss), Tax	101	22
Net actuarial gain (loss) - net of deferred taxes	476	68
Prior service credit (costs), tax	0	5
Net curtailment/settlement, tax	16	0
Net curtailment/settlement - net of deferred taxes	30	0
Prior service cost amortization, tax	19	21
Prior service cost amortization - net of deferred taxes	11	16
Net actuarial loss amortization, tax	253	216
Net actuarial loss amortization - net of deferred taxes	533	443
Less Other comprehensive income (loss) attributable to noncontrolling interests	2	(1)
Accumulated Other Comprehensive Income (Loss) Ending balance	$ (11,421)	$ (10,859)	$ (12,469)