Income Taxes - Reconciliation of unrecognized tax benefits (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Reconciliation of the change in the amount of unrecognized tax benefits
Balance – beginning of year	$ 12	$ 70	$ 70
Acquisitions	5	0	0
Decrease for settlements	0	(58)	0
Balance – end of year	$ 17	$ 12	$ 70