Stock Based Compensation - Stock Based Compensation Expense (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock based compensation expense	$ 18	$ 13	$ 30	$ 24
Cost of providing services
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock based compensation expense	4	3	6	6
Sales and marketing
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock based compensation expense	2	2	3	3
General and administrative
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock based compensation expense	11	7	19	13
Systems development and programming costs
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock based compensation expense	$ 1	$ 1	$ 2	$ 2