Income Taxes Effective Income Tax Rate Reconciliation (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Income tax benefit (expense) at U.S. statutory rate	$ 543	$ 365	$ (47)
Valuation allowance	(243)	(63)	(4)
Non-controlling interest	(6)	(4)	26
Goodwill impairment			(18)
Stock dispositions			69
Income not subject to taxation	(287)	(314)	14
State taxes	103
Other	6	(4)	(26)
Income tax benefit (expense)	$ 116	$ (20)	$ 14