Benefit Plans (Components of Pension and Other Employee Benefits Costs) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total pension and other employee benefit costs	$ 27	$ 23	$ 82	$ 68
Pension Plan
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total pension and other employee benefit costs	(2)	(5)	(4)	(13)
Postemployment Benefit Plans
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total pension and other employee benefit costs	27	26	80	75
Postretirement Benefit Costs
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Total pension and other employee benefit costs	$ 2	$ 2	$ 6	$ 6