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, 2024	Dec. 31, 2023
Debt Securities
Cash equivalents:	$ 165	$ 190
Amortized Cost	427	457
Gross Unrealized Gains	4	2
Gross Unrealized Losses	0	(3)
Fair Value	431	456
Cash and Cash Equivalents
Debt Securities
Cash equivalents:	77	101
Fair Value	0	0
Investments
Debt Securities
Cash equivalents:	0	0
Fair Value	195	208
Restricted Cash, Cash Equivalents and Investments
Debt Securities
Cash equivalents:	88	89
Fair Value	236	248
Asset-backed securities | Level 2
Debt Securities
Amortized Cost	40	41
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	(1)
Fair Value	40	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	40	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	126	135
Gross Unrealized Gains	2	1
Gross Unrealized Losses	0	0
Fair Value	128	136
Corporate bonds | Level 2 | Cash and Cash Equivalents
Debt Securities
Fair Value	0	0
Corporate bonds | Level 2 | Investments
Debt Securities
Fair Value	93	103
Corporate bonds | Level 2 | Restricted Cash, Cash Equivalents and Investments
Debt Securities
Fair Value	35	33
Agency securities | Level 2
Debt Securities
Amortized Cost	28	40
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	(1)
Fair Value	28	39
Agency securities | Level 2 | Cash and Cash Equivalents
Debt Securities
Fair Value	0	0
Agency securities | Level 2 | Investments
Debt Securities
Fair Value	6	10
Agency securities | Level 2 | Restricted Cash, Cash Equivalents and Investments
Debt Securities
Fair Value	22	29
U.S. treasuries | Level 2
Debt Securities
Amortized Cost	225	231
Gross Unrealized Gains	2	1
Gross Unrealized Losses	0	(1)
Fair Value	227	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	50	47
U.S. treasuries | Level 2 | Restricted Cash, Cash Equivalents and Investments
Debt Securities
Fair Value	177	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	6	8
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Fair Value	6	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	6	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:	164	183
Money market mutual funds | Level 1 | Cash and Cash Equivalents
Debt Securities
Cash equivalents:	77	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:	87	87
U.S. treasuries | Level 2
Debt Securities
Cash equivalents:	1	7
U.S. treasuries | Level 2 | Cash and Cash Equivalents
Debt Securities
Cash equivalents:	0	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:	$ 1	$ 2