Segment Reporting - Schedule of Current Reportable and Recast of Segments by Revenue (Details) - USD ($) $ in Millions	3 Months Ended				6 Months Ended	9 Months Ended	12 Months Ended
	Mar. 31, 2023	Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022	Jun. 30, 2022	Sep. 30, 2022	Dec. 31, 2022
Segment Reporting Information [Line Items]
Revenue	$ 831	$ 750	$ 715	$ 725	$ 1,440	$ 2,190	$ 3,132
Employer Solutions
Segment Reporting Information [Line Items]
Revenue	723	645	614	623	1,237	1,882	2,718
Employer Solutions | Recurring
Segment Reporting Information [Line Items]
Revenue	669	583	559	570	1,129	1,712	2,467
Employer Solutions | Project
Segment Reporting Information [Line Items]
Revenue	54	62	55	53	108	170	251
Professional Services
Segment Reporting Information [Line Items]
Revenue	98	95	91	90	181	276	371
Professional Services | Recurring
Segment Reporting Information [Line Items]
Revenue	33	32	32	30	62	94	128
Professional Services | Project
Segment Reporting Information [Line Items]
Revenue	65	63	59	60	119	182	243
Total Reportable Segments
Segment Reporting Information [Line Items]
Revenue	821	740	705	713	1,418	2,158	3,089
Other
Segment Reporting Information [Line Items]
Revenue	$ 10	$ 10	$ 10	$ 12	$ 22	$ 32	$ 43