Provision (Benefit) for Income Taxes Reconciliations to Recorded Tax Provision (Benefit) Table (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Effective Income Tax Rate Reconciliation [Abstract]
Provision (benefit) at statutory rate	$ 58	$ 224	$ 69
Increases (decreases) in taxes resulting from:
Impact of nontaxable noncontrolling interests	3	29	(73)
State income taxes (net of federal benefit)	6	74	(10)
State deferred income tax rate change	0	0	38
Federal valuation allowance	1	3	105
Other – net	11	5	9
Less: Provision (benefit) for income taxes	$ 79	$ 335	$ 138