Income Taxes - Deferred Income Tax Valuation Allowance Reconciliation (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Deferred Tax Assets Valuation Allowance [Roll Forward]
Beginning balance of deferred income tax valuation allowance	$ 119	$ 126	$ 122
Charges against goodwill	1	0	15
Decreases	(1)	(7)	(11)
Ending balance of deferred income tax valuation allowance	$ 119	$ 119	$ 126