CASH, CASH EQUIVALENTS AND INVESTMENTS - UNRESTRICTED AND RESTRICTED (Details) - USD ($) $ in Millions	Jun. 30, 2023	Dec. 31, 2022
Restricted Cash and Cash Equivalents Items [Line Items]
Cash and cash equivalents	$ 482	$ 354
Investments	69	76
Total restricted cash, cash equivalents and investments	1,074	1,263
Investments, noncurrent	146	151
Restricted cash, cash equivalents and investments, noncurrent	157	153
Total	1,928	1,997
Cash and cash equivalents
Restricted Cash and Cash Equivalents Items [Line Items]
Cash and cash equivalents	482	354
Investments	0	0
Total restricted cash, cash equivalents and investments	964	1,153
Investments, noncurrent	0	0
Total	1,473	1,537
Available-for-sale marketable securities
Restricted Cash and Cash Equivalents Items [Line Items]
Cash and cash equivalents	0	0
Investments	69	76
Total restricted cash, cash equivalents and investments	110	110
Investments, noncurrent	146	151
Total	455	460
Payroll funds collected
Restricted Cash and Cash Equivalents Items [Line Items]
Total restricted cash, cash equivalents and investments	875	1,062
Payroll funds collected | Cash and cash equivalents
Restricted Cash and Cash Equivalents Items [Line Items]
Total restricted cash, cash equivalents and investments	875	1,062
Payroll funds collected | Available-for-sale marketable securities
Restricted Cash and Cash Equivalents Items [Line Items]
Total restricted cash, cash equivalents and investments	0	0
Collateral for health benefits claims
Restricted Cash and Cash Equivalents Items [Line Items]
Total restricted cash, cash equivalents and investments	141	139
Collateral for health benefits claims | Cash and cash equivalents
Restricted Cash and Cash Equivalents Items [Line Items]
Total restricted cash, cash equivalents and investments	31	29
Collateral for health benefits claims | Available-for-sale marketable securities
Restricted Cash and Cash Equivalents Items [Line Items]
Total restricted cash, cash equivalents and investments	110	110
Collateral for workers' compensation claims
Restricted Cash and Cash Equivalents Items [Line Items]
Total restricted cash, cash equivalents and investments	55	58
Restricted cash, cash equivalents and investments, noncurrent	154	150
Collateral for workers' compensation claims | Cash and cash equivalents
Restricted Cash and Cash Equivalents Items [Line Items]
Total restricted cash, cash equivalents and investments	55	58
Restricted cash, cash equivalents and investments, noncurrent	24	27
Collateral for workers' compensation claims | Available-for-sale marketable securities
Restricted Cash and Cash Equivalents Items [Line Items]
Total restricted cash, cash equivalents and investments	0	0
Restricted cash, cash equivalents and investments, noncurrent	130	123
Other security deposits
Restricted Cash and Cash Equivalents Items [Line Items]
Total restricted cash, cash equivalents and investments	3	4
Restricted cash, cash equivalents and investments, noncurrent	3	3
Other security deposits | Cash and cash equivalents
Restricted Cash and Cash Equivalents Items [Line Items]
Total restricted cash, cash equivalents and investments	3	4
Restricted cash, cash equivalents and investments, noncurrent	3	3
Other security deposits | Available-for-sale marketable securities
Restricted Cash and Cash Equivalents Items [Line Items]
Total restricted cash, cash equivalents and investments	0	0
Restricted cash, cash equivalents and investments, noncurrent	$ 0	$ 0