Retirement Benefits (Reconciliation of Prior Service Credit) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Pension Benefits
Recognized as component of net periodic benefit credit:
Total recognized as component of net periodic benefit credit	$ (234)	$ (181)	$ (130)
Post-retirement Benefits
Recognized as component of net periodic benefit credit:
Total recognized as component of net periodic benefit credit	0	1	6
Non-U.S. | Pension Benefits
Recognized as component of net periodic benefit credit:
Total recognized as component of net periodic benefit credit	(176)	(114)	(74)
Non-U.S. | Post-retirement Benefits
Recognized as component of net periodic benefit credit:
Total recognized as component of net periodic benefit credit	0	1	2
Non-U.S. | Prior Service Credit (Cost) | Pension Benefits
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	(2)	43
Recognized as component of net periodic benefit credit:
Amortization of prior service credit	0	(2)
Total recognized as component of net periodic benefit credit	0	(2)
Plan amendments	1	(44)
Exchange rate adjustments	(1)	1
Ending balance	(2)	(2)	43
Non-U.S. | Prior Service Credit (Cost) | Post-retirement Benefits
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Beginning balance	12	15
Recognized as component of net periodic benefit credit:
Amortization of prior service credit	(2)	(2)
Total recognized as component of net periodic benefit credit	(2)	(2)
Plan amendments	0	0
Exchange rate adjustments	1	(1)
Ending balance	$ 11	$ 12	$ 15