Postretirement Benefit Plans (Summary of Net Periodic Benefit Cost) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Net periodic benefit cost:
Amortization of net actuarial loss	$ 1	$ 1	$ 1	$ 2
Net periodic benefit cost	6	12	22	13
Domestic defined benefit pension plans
Net periodic benefit cost:
Service cost	0	1	2	2
Interest cost	1	1	3	3
Expected return on plan assets	(1)	(2)	(5)	(6)
Amortization of net actuarial loss	0		2	1
Net periodic benefit cost	0		2
International defined benefit pension plans
Net periodic benefit cost:
Service cost	3	2	9	7
Interest cost	3	4	11	14
Expected return on plan assets	(4)	(4)	(10)	(22)
Amortization of net actuarial loss	4	2	10	6
Settlement/Curtailment	0	8	0	8
Net periodic benefit cost	$ 6	$ 12	$ 20	$ 13