Benefit Plans (Termination, Settlement and Curtailment Costs) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Pension [Member]
Defined Benefit Plan Disclosure [Line Items]
Benefit obligation	$ 6	$ 0	$ 0
Net loss	20	13	86
Prior service cost (credit)	1	3	0
Termination, settlement, and curtailment costs	27	16	86
Postretirement Benefit Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Benefit obligation	10
Net loss	0
Prior service cost (credit)	(5)
Termination, settlement, and curtailment costs	$ 5	$ 0	$ 0