INVESTMENTS - Schedule of Financial Instruments by Significant Categories and Fair Value Measurement on a Recurring Basis (Details) - Fair Value Measurement on a Recurring Basis - USD ($) $ in Millions	Sep. 30, 2023	Dec. 31, 2022
Debt Securities
Cash equivalents:	$ 138	$ 332
Amortized Cost	469	464
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(8)	(4)
Fair Value	461	460
Cash and Cash Equivalents
Debt Securities
Cash equivalents:	51	243
Fair Value	0	0
Investments
Debt Securities
Cash equivalents:	0	0
Fair Value	219	226
Restricted Cash, Cash Equivalents and Investments
Debt Securities
Cash equivalents:	87	89
Fair Value	242	234
Asset-backed securities | Level 2
Debt Securities
Amortized Cost	45	42
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(1)	(2)
Fair Value	44	40
Asset-backed securities | Level 2 | Cash and Cash Equivalents
Debt Securities
Fair Value	0	0
Asset-backed securities | Level 2 | Investments
Debt Securities
Fair Value	44	40
Asset-backed securities | Level 2 | Restricted Cash, Cash Equivalents and Investments
Debt Securities
Fair Value	0	0
Corporate bonds | Level 2
Debt Securities
Amortized Cost	131	140
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(1)	(1)
Fair Value	130	139
Corporate bonds | Level 2 | Cash and Cash Equivalents
Debt Securities
Fair Value	0	0
Corporate bonds | Level 2 | Investments
Debt Securities
Fair Value	102	112
Corporate bonds | Level 2 | Restricted Cash, Cash Equivalents and Investments
Debt Securities
Fair Value	28	27
Agency securities | Level 2
Debt Securities
Amortized Cost	40	33
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(1)	(1)
Fair Value	39	32
Agency securities | Level 2 | Cash and Cash Equivalents
Debt Securities
Fair Value	0	0
Agency securities | Level 2 | Investments
Debt Securities
Fair Value	11	5
Agency securities | Level 2 | Restricted Cash, Cash Equivalents and Investments
Debt Securities
Fair Value	28	27
U.S. treasuries | Level 2
Debt Securities
Amortized Cost	241	229
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(5)	0
Fair Value	236	229
U.S. treasuries | Level 2 | Cash and Cash Equivalents
Debt Securities
Fair Value	0	0
U.S. treasuries | Level 2 | Investments
Debt Securities
Fair Value	57	62
U.S. treasuries | Level 2 | Restricted Cash, Cash Equivalents and Investments
Debt Securities
Fair Value	179	167
Certificate of deposit | Level 2
Debt Securities
Amortized Cost	7	12
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Fair Value	7	12
Certificate of deposit | Level 2 | Cash and Cash Equivalents
Debt Securities
Fair Value	0	0
Certificate of deposit | Level 2 | Investments
Debt Securities
Fair Value	0	0
Certificate of deposit | Level 2 | Restricted Cash, Cash Equivalents and Investments
Debt Securities
Fair Value	7	12
Other debt securities | Level 2
Debt Securities
Amortized Cost	5	8
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Fair Value	5	8
Other debt securities | Level 2 | Cash and Cash Equivalents
Debt Securities
Fair Value	0	0
Other debt securities | Level 2 | Investments
Debt Securities
Fair Value	5	7
Other debt securities | Level 2 | Restricted Cash, Cash Equivalents and Investments
Debt Securities
Fair Value	0	1
Money market mutual funds | Level 1
Debt Securities
Cash equivalents:	134	314
Money market mutual funds | Level 1 | Cash and Cash Equivalents
Debt Securities
Cash equivalents:	47	225
Money market mutual funds | Level 1 | Investments
Debt Securities
Cash equivalents:	0	0
Money market mutual funds | Level 1 | Restricted Cash, Cash Equivalents and Investments
Debt Securities
Cash equivalents:	87	89
U.S. treasuries | Level 2
Debt Securities
Cash equivalents:	4	18
U.S. treasuries | Level 2 | Cash and Cash Equivalents
Debt Securities
Cash equivalents:	4	18
U.S. treasuries | Level 2 | Investments
Debt Securities
Cash equivalents:	0	0
U.S. treasuries | Level 2 | Restricted Cash, Cash Equivalents and Investments
Debt Securities
Cash equivalents:	$ 0	$ 0