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	Mar. 31, 2024	Dec. 31, 2023
Debt Securities
Cash equivalents:	$ 331	$ 190
Amortized Cost	493	457
Gross Unrealized Gains	0	2
Gross Unrealized Losses	(5)	(3)
Fair Value	488	456
Cash and Cash Equivalents
Debt Securities
Cash equivalents:	41	101
Fair Value	0	0
Investments
Debt Securities
Cash equivalents:	0	0
Fair Value	246	208
Restricted Cash, Cash Equivalents and Investments
Debt Securities
Cash equivalents:	290	89
Fair Value	242	248
Asset-backed securities | Level 2
Debt Securities
Amortized Cost	38	41
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	(1)
Fair Value	38	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	38	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	148	135
Gross Unrealized Gains	0	1
Gross Unrealized Losses	0	0
Fair Value	148	136
Corporate bonds | Level 2 | Cash and Cash Equivalents
Debt Securities
Fair Value	0	0
Corporate bonds | Level 2 | Investments
Debt Securities
Fair Value	115	103
Corporate bonds | Level 2 | Restricted Cash, Cash Equivalents and Investments
Debt Securities
Fair Value	33	33
Agency securities | Level 2
Debt Securities
Amortized Cost	37	40
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(1)	(1)
Fair Value	36	39
Agency securities | Level 2 | Cash and Cash Equivalents
Debt Securities
Fair Value	0	0
Agency securities | Level 2 | Investments
Debt Securities
Fair Value	8	10
Agency securities | Level 2 | Restricted Cash, Cash Equivalents and Investments
Debt Securities
Fair Value	28	29
U.S. treasuries | Level 2
Debt Securities
Amortized Cost	260	231
Gross Unrealized Gains	0	1
Gross Unrealized Losses	(4)	(1)
Fair Value	256	231
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	77	47
U.S. treasuries | Level 2 | Restricted Cash, Cash Equivalents and Investments
Debt Securities
Fair Value	179	184
Certificate of deposit | Level 2
Debt Securities
Amortized Cost	2	2
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Fair Value	2	2
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	2	2
Other debt securities | Level 2
Debt Securities
Amortized Cost	8	8
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Fair Value	8	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	8	8
Other debt securities | Level 2 | Restricted Cash, Cash Equivalents and Investments
Debt Securities
Fair Value	0	0
Money market mutual funds | Level 1
Debt Securities
Cash equivalents:	327	183
Money market mutual funds | Level 1 | Cash and Cash Equivalents
Debt Securities
Cash equivalents:	40	96
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:	287	87
U.S. treasuries | Level 2
Debt Securities
Cash equivalents:	4	7
U.S. treasuries | Level 2 | Cash and Cash Equivalents
Debt Securities
Cash equivalents:	1	5
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:	$ 3	$ 2