Retirement Benefits Plans - Change in Plan Assets (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Change in plan assets
Balance at January 1	$ 4,406
Balance at December 31	4,447	$ 4,406
United States pension liabilities [Member]
Change in plan assets
Balance at January 1	2,934	3,086
Actual return on plan assets	221	(55)
Employer contributions	160	221	$ 248
Gross benefits paid	(346)	(318)
Currency translation	0	0
Other	0	0
Balance at December 31	2,969	2,934	3,086
Non-United States pension liabilities [Member]
Change in plan assets
Balance at January 1	1,472	1,535
Actual return on plan assets	212	29
Employer contributions	102	109	114
Gross benefits paid	(94)	(100)
Currency translation	(211)	(101)
Other	(3)	0
Balance at December 31	1,478	1,472	1,535
Other postretirement liabilities [Member]
Change in plan assets
Balance at January 1	93	116
Actual return on plan assets	3	1
Employer contributions	30	31
Gross benefits paid	(79)	(86)
Currency translation	0	0
Other	27	31
Balance at December 31	$ 74	$ 93	$ 116