Income Taxes (Income Tax (Provision) Benefit Attributable To Income From Continuing Operations) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Current:
U.S. federal	$ 8	$ 0	$ 5
U.S. state	(3)	(2)	0
Current income tax (provision) benefit	5	(2)	5
Deferred:
U.S. federal	(224)	(258)	526
U.S. state	(12)	(16)	(7)
Deferred income tax benefit	(236)	(274)	519
Income tax (provision) benefit	$ (231)	$ (276)	$ 524