Retirement Benefits - Expense (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended			12 Months Ended			24 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2013
U.S. Plans
Defined Benefit Plan Disclosure [Line Items]
Service cost				$ 507	$ 581	$ 521
Interest cost				1,992	1,914	2,208
Expected return on assets				(2,713)	(2,816)	(2,873)
Defined Benefit Plan Amortization Categories [Abstract]
Amortization of prior service costs/(credits)				155	174	220
Amortization of (gains)/losses				207	655	425
Separation programs/other				19	10	7
Recognition of (gains)/losses due to curtailments				0	0	0
Recognition of (gains)/losses due to settlements	155	145	294	0	594	250	844
Total expense/(income)				167	1,112	758
Non-U.S. Plans
Defined Benefit Plan Disclosure [Line Items]
Service cost				468	484	372
Interest cost				1,189	1,137	1,189
Expected return on assets				(1,508)	(1,382)	(1,340)
Defined Benefit Plan Amortization Categories [Abstract]
Amortization of prior service costs/(credits)				55	66	72
Amortization of (gains)/losses				586	686	412
Separation programs/other				81	242	162
Recognition of (gains)/losses due to curtailments				0	0	0
Recognition of (gains)/losses due to settlements				19	5	0
Total expense/(income)				890	1,238	867
Worldwide OPEB [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost				54	64	67
Interest cost				269	256	290
Expected return on assets				0	0	0
Defined Benefit Plan Amortization Categories [Abstract]
Amortization of prior service costs/(credits)				(229)	(283)	(545)
Amortization of (gains)/losses				98	158	129
Separation programs/other				0	0	2
Recognition of (gains)/losses due to curtailments				0	(2)	(11)
Recognition of (gains)/losses due to settlements				0	0	0
Total expense/(income)				$ 192	$ 193	$ (68)