Retirement Benefits - Expense (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Defined Benefit Plan Amortization Categories [Abstract]
(Gains)/Losses from curtailment and settlements			$ 29
U.S. Plans
Defined Benefit Plan Disclosure [Line Items]
Service cost	521	467	376
Interest cost	2,208	2,374	2,530
Expected return on assets	(2,873)	(3,028)	(3,172)
Defined Benefit Plan Amortization Categories [Abstract]
Prior service costs/(credits)	220	343	370
(Gains)/Losses	425	194	20
Separation programs/other	7	1	(2)
(Gains)/Losses from curtailment and settlements	250
Net expense/(income)	758	351	122
Non-U.S. Plans
Defined Benefit Plan Disclosure [Line Items]
Service cost	372	327	314
Interest cost	1,189	1,227	1,249
Expected return on assets	(1,340)	(1,404)	(1,337)
Defined Benefit Plan Amortization Categories [Abstract]
Prior service costs/(credits)	72	72	75
(Gains)/Losses	412	301	218
Separation programs/other	162	170	54
(Gains)/Losses from curtailment and settlements	0	111
Net expense/(income)	867	804	573
Worldwide OPEB [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	67	63	54
Interest cost	290	327	338
Expected return on assets
Defined Benefit Plan Amortization Categories [Abstract]
Prior service costs/(credits)	(545)	(612)	(617)
(Gains)/Losses	129	94	92
Separation programs/other	2	10	5
(Gains)/Losses from curtailment and settlements	(11)	(26)	(30)
Net expense/(income)	$ (68)	$ (144)	$ (158)