Income Taxes (Provision (Benefit) for Income Taxes) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Current:
Federal	$ (2)	$ (1)	$ (5)
State	0	(1)	6
Total Current	(2)	(2)	1
Deferred:
Federal	371	(431)	0
State	38	22	0
Total Deferred	409	(409)	0
Provision (Benefit) for Income Taxes	$ 407	$ (411)	$ 1