Retirement Benefits (Reconciliation of Net Actuarial Loss) (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 cost (credit):
Total recognized as component of net periodic benefit cost (credit)	$ (234)	$ (181)	$ (130)
Post-retirement Benefits
Recognized as component of net periodic benefit cost (credit):
Total recognized as component of net periodic benefit cost (credit)	0	1	6
U.S. | Pension Benefits
Recognized as component of net periodic benefit cost (credit):
Other	(49)	0
U.S. | Post-retirement Benefits
Recognized as component of net periodic benefit cost (credit):
Other	0	0
U.S. | Net Actuarial (Loss) Gain | Pension Benefits
Reconciliation of unrecognized net actuarial gain loss [Roll Forward]
Beginning balance	(1,896)	(1,766)
Recognized as component of net periodic benefit cost (credit):
Amortization of net loss	44	55
Liability experience	(753)	502
Asset experience	491	(687)
Total amount recognized as change in plan assets and benefit obligations	(262)	(185)
Ending balance	(2,114)	(1,896)	(1,766)
U.S. | Net Actuarial (Loss) Gain | Post-retirement Benefits
Reconciliation of unrecognized net actuarial gain loss [Roll Forward]
Beginning balance	6	6
Recognized as component of net periodic benefit cost (credit):
Amortization of net loss	(1)	(1)
Liability experience	(1)	1
Asset experience	0	0
Total amount recognized as change in plan assets and benefit obligations	(1)	1
Ending balance	4	6	6
Non-U.S. | Pension Benefits
Recognized as component of net periodic benefit cost (credit):
Total recognized as component of net periodic benefit cost (credit)	(176)	(114)	(74)
Non-U.S. | Post-retirement Benefits
Recognized as component of net periodic benefit cost (credit):
Total recognized as component of net periodic benefit cost (credit)	0	1	2
Non-U.S. | Net Actuarial (Loss) Gain | Pension Benefits
Reconciliation of unrecognized net actuarial gain loss [Roll Forward]
Beginning balance	(2,568)	(2,646)
Recognized as component of net periodic benefit cost (credit):
Amortization of net loss	60	91
Effect of settlement	7	42
Total recognized as component of net periodic benefit cost (credit)	67	133
Liability experience	(1,339)	450
Asset experience	847	(648)
Other	0	3
Total amount recognized as change in plan assets and benefit obligations	(492)	(195)
Exchange rate adjustments	(62)	140
Ending balance	(3,055)	(2,568)	(2,646)
Non-U.S. | Net Actuarial (Loss) Gain | Post-retirement Benefits
Reconciliation of unrecognized net actuarial gain loss [Roll Forward]
Beginning balance	(1)	(10)
Recognized as component of net periodic benefit cost (credit):
Amortization of net loss	0	0
Effect of settlement	0	0
Total recognized as component of net periodic benefit cost (credit)	0	0
Liability experience	(3)	8
Asset experience	0	0
Other	0	0
Total amount recognized as change in plan assets and benefit obligations	(3)	8
Exchange rate adjustments	(1)	1
Ending balance	$ (5)	$ (1)	$ (10)