Segment Reporting - Schedule of Current Reportable and Recast of Segments by Revenue (Details) - USD ($) $ in Millions	3 Months Ended			9 Months Ended
	Sep. 30, 2025	Jun. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024
Revenue
Revenue	$ 533		$ 555	$ 1,609	$ 1,652
Less
Cost of sales	327		358	1,003	1,059
Depreciation and amortization	28		23	81	70
Gross Profit	178		174	525	523
Selling, general and administrative	87		142	321	434
Depreciation and intangible amortization	75		74	223	223
Goodwill impairment	1,338	$ 983	0	2,321	0
Interest expense	24		19	68	83
Net Income (Loss) From Continuing Operations	(1,055)		(44)	(2,145)	(169)
Employer Solutions
Revenue
Revenue	533		555	1,609	1,652
Less
Stock Based Compensation	0		3	5	11
Depreciation and amortization	28		23	81	70
Gross Profit	178		174	525	523
Selling, general and administrative	80		122	268	341
Restructuring	4		12	44	45
Stock Based Compensation	3		8	9	48
Depreciation and intangible amortization	75		74	223	223
Goodwill impairment	1,338		0	2,321	0
Interest expense	24		19	68	83
Other segment item	(291)		(17)	(263)	(48)
Net Income (Loss) From Continuing Operations	(1,055)		(44)	(2,145)	(169)
Employer Solutions | Technology
Less
Cost of sales	76		75	228	239
Employer Solutions | Delivery, Customer Care, and Other
Less
Cost of sales	251		280	770	809
Employer Solutions | Recurring
Revenue
Revenue	489		504	1,501	1,518
Employer Solutions | Project
Revenue
Revenue	$ 44		$ 51	$ 108	$ 134