Income Taxes - Current and Deferred (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Federal	$ 30	$ (10)	$ 8
State	7	(1)	0
Current Income Tax Expense (Benefit)	37	(11)	8
Federal	2	(253)	(11)
State	10	1	(10)
Deferred income taxes	12	(252)	(21)
Total income tax expense (benefit)	$ 49	$ (263)	$ (13)