Income Taxes (Unrecognized Tax Benefits) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Amount	$ 20	$ 45	$ 26
Increases in unrecognized tax benefits—prior years	0	20	11
(Decreases) in unrecognized tax benefits—prior years	(2)	0	(5)
Increases in unrecognized tax benefits—current year	0	0	14
(Decreases) in unrecognized tax benefits—current year	0	0	0
Settlements with taxing authorities	0	(45)	(1)
Amount	18	20	45
Unrecognized tax benefits that, if recognized, would favorably impact the effective rate	$ 0	$ 0	$ 45