Retirement Benefits - Expense (Details) - USD ($) $ in Millions	3 Months Ended			9 Months Ended
	Sep. 30, 2015	Mar. 31, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014
Defined Benefit Plan Disclosure [Line Items]
Other Assets	$ 7,524			$ 7,524		$ 6,353
Other Liabilities and deferred revenue	42,513			42,513		$ 43,577
Other Comprehensive Income/(Loss), Pension and Other Postretirement Benefit Plans, Adjustment, net of Tax	481		$ 540	726	$ 776
U.S. Plans
Defined Benefit Plan Disclosure [Line Items]
Service cost	147		127	440	380
Interest cost	454		498	1,363	1,494
Expected return on assets	(689)		(678)	(2,066)	(2,034)
Defined Benefit Plan Amortization Categories [Abstract]
Prior service costs/(credits)	38		38	116	116
(Gains)/Losses	116		52	348	155
Separation programs/other	6		8	7	9
(Gains)/Losses from curtailments	0		0	0	0
(Gains)/Losses from settlements	0		0	0	0
Total expense/(income)	72		45	208	120
Non-U.S. Plans
Defined Benefit Plan Disclosure [Line Items]
Service cost	133		118	401	356
Interest cost	236		302	707	904
Expected return on assets	(346)		(383)	(1,038)	(1,145)
Defined Benefit Plan Amortization Categories [Abstract]
Prior service costs/(credits)	13		15	36	42
(Gains)/Losses	200		149	604	445
Separation programs/other	11		15	30	54
(Gains)/Losses from curtailments	0		0	0	0
(Gains)/Losses from settlements	9		0	9	14
Total expense/(income)	256		216	749	670
Worldwide OPEB
Defined Benefit Plan Disclosure [Line Items]
Service cost	15		13	45	40
Interest cost	59		68	178	202
Expected return on assets	0		0	0	0
Defined Benefit Plan Amortization Categories [Abstract]
Prior service costs/(credits)	(51)		(58)	(154)	(172)
(Gains)/Losses	36		24	107	73
Separation programs/other	(1)		1	1	1
(Gains)/Losses from curtailments	0		0	0	0
(Gains)/Losses from settlements	0		0	0	0
Total expense/(income)	58		$ 48	177	$ 144
Plan Contributions [Abstract]
Defined Benefit Plan, Estimated Future Employer Contributions To Funded Plans in Current Fiscal Year	1,100			1,100
Pension And Other Postretirement Expected Benefit Contributions Unfunded Plans	400			400
Pension and Other Postretirement Benefit Contributions and Expected Future Employer Contributions To Funded and Unfunded Plans	$ 1,500			1,500
Pension and Other Postretirement Benefit Contributions				900
Pension and Other Postretirement Benefit Contributions Unfunded Plans				$ 300
2014 U.S. Pension Benefit Obligation Valuation Adjustment [Member]
Defined Benefit Plan Disclosure [Line Items]
Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Adjustment, before Tax		$ (782)
Other Assets		(301)
Other Liabilities and deferred revenue		481
Other Comprehensive Income/(Loss), Pension and Other Postretirement Benefit Plans, Adjustment, net of Tax		$ (508)