Benefit Plans (Termination, Settlement and Curtailment Costs) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Pension [Member]
Defined Benefit Plan Disclosure [Line Items]
Benefit obligation	$ 0	$ 0	$ 23
Net loss	13	86	9
Prior service cost (credit)	3	0	2
Termination, settlement, and curtailment costs	16	86	34
Postretirement Benefit Plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Benefit obligation			11
Net loss			0
Prior service cost (credit)			(13)
Termination, settlement, and curtailment costs	$ 0	$ 0	$ (2)