Benefit Plans (Components of Pension and Other Employee Benefits Costs) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total pension and other employee benefit costs	$ 22	$ 20	$ 45	$ 41
Pension Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total pension and other employee benefit costs	(4)	(5)	(8)	(10)
Postemployment Benefit Plans [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total pension and other employee benefit costs	24	23	49	47
Postretirement Benefit Costs [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total pension and other employee benefit costs	$ 2	$ 2	$ 4	$ 4