Income Taxes (Provision (Benefit) For Income Taxes) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Current:
Federal	$ (6)	$ 1	$ 11
State	(1)	(3)	10
Total	(7)	(2)	21
Deferred:
Federal	(22)	(1,697)	501
State		(304)	2
Foreign		(2)	1
Total	(22)	(2,003)	504
Provision (Benefit) for Income Taxes	$ (29)	$ (2,005)	$ 525