Income Taxes - Unrecognized Tax Benefits (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Unrecognized Tax Benefits, Income Tax Penalties and Interest Expense [Abstract]
Unrecognized tax benefits, balance	$ 33	$ 37	$ 36
Additions for tax positions related to current year	1	2	2
Additions for tax positions related to prior years	0	1	0
Reductions for tax positions related to prior years	(2)	(1)	0
Reductions for settlements with taxing authorities	0	(6)	0
Reductions for expiring statutes	0	0	(1)
Unrecognized tax benefits, balance	32	33	37
Unrecognized tax benefits that would affect effective rate	$ 1	$ 1	$ 8