Income Taxes - Unrecognized Tax Benefits (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Reconciliation of unrecognized tax benefits
Balance at January 1,	$ 25	$ 26	$ 20
Additions based on tax positions related to the current year	1	0	0
Additions for tax positions of prior years	0	1	9
Reductions for tax positions of prior years	(3)	(2)	(3)
Balance at December 31,	$ 23	$ 25	$ 26