Benefit Plans (Pension and Other Employee Benefit Costs) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Defined Benefit Plan Disclosure [Line Items]
Total pension and other employee benefit costs	$ 89	$ 41	$ 78
Pension [Member]
Defined Benefit Plan Disclosure [Line Items]
Total pension and other employee benefit costs	(18)	(51)	(20)
Postemployment Benefit Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Total pension and other employee benefit costs	100	80	85
Postretirement Benefit Costs [Member]
Defined Benefit Plan Disclosure [Line Items]
Total pension and other employee benefit costs	$ 7	$ 12	$ 13