CASH, CASH EQUIVALENTS AND INVESTMENTS - UNRESTRICTED AND RESTRICTED (Details) - USD ($) $ in Millions	Sep. 30, 2025	Dec. 31, 2024
Restricted Cash and Cash Equivalent Item [Line Items]
Cash and cash equivalents	$ 321	$ 360
Total restricted cash, cash equivalents and investments	1,108	1,413
Collateral for workers' compensation claims	125	145
Total	1,554	1,918
Payroll funds collected
Restricted Cash and Cash Equivalent Item [Line Items]
Total restricted cash, cash equivalents and investments	846	1,131
Collateral for health benefits claims
Restricted Cash and Cash Equivalent Item [Line Items]
Total restricted cash, cash equivalents and investments	150	144
Collateral for workers' compensation claims
Restricted Cash and Cash Equivalent Item [Line Items]
Total restricted cash, cash equivalents and investments	48	49
Collateral for workers' compensation claims	125	145
Trust for our HRIS Users
Restricted Cash and Cash Equivalent Item [Line Items]
Total restricted cash, cash equivalents and investments	63	87
Other security deposits
Restricted Cash and Cash Equivalent Item [Line Items]
Total restricted cash, cash equivalents and investments	1	2
Cash and cash equivalents
Restricted Cash and Cash Equivalent Item [Line Items]
Cash and cash equivalents	321	360
Total restricted cash, cash equivalents and investments	995	1,303
Total	1,346	1,691
Cash and cash equivalents | Payroll funds collected
Restricted Cash and Cash Equivalent Item [Line Items]
Total restricted cash, cash equivalents and investments	846	1,131
Cash and cash equivalents | Collateral for health benefits claims
Restricted Cash and Cash Equivalent Item [Line Items]
Total restricted cash, cash equivalents and investments	37	34
Cash and cash equivalents | Collateral for workers' compensation claims
Restricted Cash and Cash Equivalent Item [Line Items]
Total restricted cash, cash equivalents and investments	48	49
Collateral for workers' compensation claims	30	28
Cash and cash equivalents | Trust for our HRIS Users
Restricted Cash and Cash Equivalent Item [Line Items]
Total restricted cash, cash equivalents and investments	63	87
Cash and cash equivalents | Other security deposits
Restricted Cash and Cash Equivalent Item [Line Items]
Total restricted cash, cash equivalents and investments	1	2
Available-for-sale marketable securities
Restricted Cash and Cash Equivalent Item [Line Items]
Cash and cash equivalents	0	0
Total restricted cash, cash equivalents and investments	113	110
Total	208	227
Available-for-sale marketable securities | Payroll funds collected
Restricted Cash and Cash Equivalent Item [Line Items]
Total restricted cash, cash equivalents and investments	0
Available-for-sale marketable securities | Collateral for health benefits claims
Restricted Cash and Cash Equivalent Item [Line Items]
Total restricted cash, cash equivalents and investments	113	110
Available-for-sale marketable securities | Collateral for workers' compensation claims
Restricted Cash and Cash Equivalent Item [Line Items]
Total restricted cash, cash equivalents and investments	0	0
Collateral for workers' compensation claims	95	117
Available-for-sale marketable securities | Trust for our HRIS Users
Restricted Cash and Cash Equivalent Item [Line Items]
Total restricted cash, cash equivalents and investments	0	0
Available-for-sale marketable securities | Other security deposits
Restricted Cash and Cash Equivalent Item [Line Items]
Total restricted cash, cash equivalents and investments	$ 0	$ 0