Provision (Benefit) for Income Taxes Tax Provison (Benefit) Table (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Current :
Federal	$ (83)	$ 15	$ 0
State	1	23	2
Foreign	0	0	(1)
Total	(82)	38	1
Deferred:
Federal	183	(2,004)	(6)
State	37	(8)	61
Foreign	0	0	(81)
Total	220	(2,012)	(26)
Provision (benefit) for income taxes	$ 138	$ (1,974)	$ (25)