Benefit Plans (Net Funded Status) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Foreign Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Benefit Obligation, Benefits Paid	$ (9)	$ (9)
Defined Benefit Plan, Benefit Obligation, Business Combination	0	0
Defined Benefit Plan, Plan Assets, Divestiture	0	(244)
Defined Benefit Plan, Benefit Obligation, Contributions by Plan Participant	0	0
CHANGE IN PROJECTED BENEFIT OBLIGATION:
Benefit obligation, beginning period	224	417
Service cost	6	8	$ 12
Interest cost	14	19	22
Defined Benefit Plan, Benefit Obligation, Interest cost	14	19
Plan amendments	0	0
Defined Benefit Plan, Benefit Obligation, (Increase) Decrease for Curtailment	(6)	0
Defined Benefit Plan, Benefit Obligation, (Increase) Decrease for Settlement	0	0
Actuarial (gain) loss	19	37
Effect of foreign currency exchange rate changes	(30)	(4)
Benefit obligation, ending period	218	224	417
CHANGE IN PLAN ASSETS:
Fair value of plan assets, beginning period	129	410
Actual return on plan assets	13	19
Employer contributions	5	5
Defined Benefit Plan, Plan Assets, Payment for Settlement	0	0
Effect of foreign currency exchange rate changes	(26)	0
Fair value of plan assets, ending period	112	129	410
Funded status as of December 31	(106)	(95)
Defined Benefit Plan, Plan Assets, Contributions by Plan Participant	0	0
Defined Benefit Plan, Plan Assets, Benefits Paid	(9)	(9)
Defined Benefit Plan, Plan Assets, Divestiture	0	(296)
UNITED STATES
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Benefit Obligation, Benefits Paid	(81)	(65)
Defined Benefit Plan, Benefit Obligation, Business Combination	0	0
Defined Benefit Plan, Plan Assets, Divestiture	0	0
Defined Benefit Plan, Benefit Obligation, Contributions by Plan Participant	0	0
CHANGE IN PROJECTED BENEFIT OBLIGATION:
Benefit obligation, beginning period	1,242	1,118
Service cost	12	11	15
Interest cost	35	44	40
Plan amendments	1	0
Defined Benefit Plan, Benefit Obligation, (Increase) Decrease for Curtailment	0	0
Defined Benefit Plan, Benefit Obligation, (Increase) Decrease for Settlement	0	0
Actuarial (gain) loss	122	134
Effect of foreign currency exchange rate changes	0	0
Benefit obligation, ending period	1,331	1,242	1,118
CHANGE IN PLAN ASSETS:
Fair value of plan assets, beginning period	1,154	1,026
Actual return on plan assets	168	185
Employer contributions	8	8
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	1,249	1,154	$ 1,026
Funded status as of December 31	(82)	(88)
Defined Benefit Plan, Plan Assets, Contributions by Plan Participant	0	0
Defined Benefit Plan, Plan Assets, Benefits Paid	(81)	(65)
Defined Benefit Plan, Plan Assets, Divestiture	$ 0	$ 0