Income Taxes - Change in Deferred Tax Asset Valuation Allowance (Details) - Valuation Allowance of Deferred Tax Assets - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Beginning Balance	$ 73	$ 93	$ 83
Additions	0	0	29
Reductions/ Charges	(4)	(20)	(19)
Ending Balance	$ 69	$ 73	$ 93