Income Taxes - Effective Income Tax Rate Reconciliation (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Income taxes at the statutory federal rate	$ 198	$ 211
Increase (decrease)
State income taxes, net of federal income tax effect	11	8
Change in valuation allowance	(207)	(213)
Capital loss expiration	0	(5)
Other	(2)	(1)
Total income tax expense	$ 0	$ 0