Income Taxes - Unrecognized Tax Benefits (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Reconciliation of unrecognized tax benefits
Balance at January 1,	$ 20	$ 30	$ 24
Additions for tax positions of prior years	9	0	7
Reductions for tax positions of prior years	(3)	(1)	(1)
Reductions related to settlements with taxing authorities	0	(9)	0
Balance at December 31,	$ 26	$ 20	$ 30