Provision (Benefit) for Income Taxes (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Current:
Federal	$ 0	$ 0	$ (2)	$ (28)
State	1	(1)	0	0
Total	1	(1)	(2)	(28)
Deferred:
Federal	85	93	200	(41)
State	33	25	62	(18)
Total	118	118	262	(59)
Provision (benefit) for income taxes	$ 119	$ 117	$ 260	$ (87)