Benefit Plans (Net Funded Status) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Foreign Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Benefit Obligation, Benefits Paid	$ (17)	$ (22)
Defined Benefit Plan, Benefit Obligation, Business Combination	4	0
Defined Benefit Plan, Benefit Obligation, Contributions by Plan Participant	1	1
CHANGE IN PROJECTED BENEFIT OBLIGATION:
Benefit obligation, beginning period	470	411
Service cost	12	10	$ 9
Interest cost	22	23	21
Defined Benefit Plan, Benefit Obligation, Interest cost	22	22
Plan amendments	0	(1)
Defined Benefit Plan, Benefit Obligation, (Increase) Decrease for Curtailment	0	0
Defined Benefit Plan, Benefit Obligation, (Increase) Decrease for Settlement	21	2
Actuarial (gain) loss	8	(29)
Effect of foreign currency exchange rate changes	(38)	22
Benefit obligation, ending period	417	470	411
CHANGE IN PLAN ASSETS:
Fair value of plan assets, beginning period	455	402
Actual return on plan assets	6	31
Employer contributions	21	18
Defined Benefit Plan, Plan Assets, Payment for Settlement	(21)	(2)
Effect of foreign currency exchange rate changes	(35)	27
Fair value of plan assets, ending period	410	455	402
Funded status as of December 31	(7)	(15)
Defined Benefit Plan, Plan Assets, Contributions by Plan Participant	1	1
Defined Benefit Plan, Plan Assets, Benefits Paid	(17)	(22)
UNITED STATES
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Plan Assets, Business Combination	0	0
CHANGE IN PROJECTED BENEFIT OBLIGATION:
Benefit obligation, beginning period	1,257	1,188
Service cost	15	13	13
Interest cost	40	41	42
Plan amendments	10	1
Defined Benefit Plan, Benefit Obligation, (Increase) Decrease for Curtailment	0	3
Defined Benefit Plan, Benefit Obligation, (Increase) Decrease for Settlement	0	0
Actuarial (gain) loss	99	(82)
Effect of foreign currency exchange rate changes	0	0
Benefit obligation, ending period	1,118	1,257	1,188
CHANGE IN PLAN ASSETS:
Fair value of plan assets, beginning period	1,127	1,044
Actual return on plan assets	(35)	141
Employer contributions	39	13
Defined Benefit Plan, Plan Assets, Payment for Settlement	0	0
Effect of foreign currency exchange rate changes	0	0
Fair value of plan assets, ending period	1,026	1,127	$ 1,044
Funded status as of December 31	(92)	(130)
Defined Benefit Plan, Plan Assets, Contributions by Plan Participant	0	0
Defined Benefit Plan, Plan Assets, Benefits Paid	$ (105)	$ (71)