Income Taxes Unrecognized Tax Benefits (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Unrecognized Tax Benefits, Increase Resulting from Current Period Tax Positions	$ 0	$ 0	$ 514
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Unrecognized tax benefits as of January 1	(416)	(514)	0
Unrecognized tax benefits as of December 31	0	(416)	(514)
Unrecognized Tax Benefit Resulting in Tax Credits and/or Net Operating Loss Carryforward		151	220
Unrecognized Tax Benefits, Decrease Resulting from Current Period Tax Positions	0	(98)	0
Unrecognized Tax Benefits, Decrease Resulting from Prior Period Tax Positions	$ (416)	$ 0	$ 0