Income Taxes Unrecognized Tax Benefits (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Unrecognized tax benefits as of January 1	$ (416)	$ (514)
Unrecognized tax benefits as of December 31	0	(416)
Unrecognized Tax Benefits, Decrease Resulting from Current Period Tax Positions	0	(98)
Unrecognized Tax Benefits, Decrease Resulting from Prior Period Tax Positions	$ (416)	0
Unrecognized Tax Benefit Resulting in Tax Credits and/or Net Operating Loss Carryforward		$ 151