Retirement Benefits Plans - Change in Plan Assets (Details 2) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Change in plan assets
Balance at December 31		$ 4,372	$ 3,855
United States pension liabilities [Member]
Change in plan assets
Balance at January 1	2,940	2,607	1,664
Actual return on plan assets		383	293
Employer contributions	254	196	311	264
Gross benefits paid		(246)	(132)
Foreign currency translation		0	0
Acquisition		0	471
Other		0	0
Balance at December 31		2,940	2,607	1,664
Non-United States pension liabilities [Member]
Change in plan assets
Balance at January 1	1,432	1,248	989
Actual return on plan assets		118	86
Employer contributions	108	145	102	108
Gross benefits paid		(90)	(78)
Foreign currency translation		15	39
Acquisition		0	128
Other		(4)	(18)
Balance at December 31		1,432	1,248	989
Other postretirement liabilities [Member]
Change in plan assets
Balance at January 1		146	156
Actual return on plan assets		15	13
Employer contributions		59	43
Gross benefits paid		(103)	(94)
Foreign currency translation		0	0
Acquisition		0	0
Other		21	28
Balance at December 31		$ 138	$ 146