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INVESTMENTS - Schedule of Financial Instruments by Significant Categories and Fair Value Measurement on a Recurring Basis (Details) - Fair Value Measurements on a Recurring Basis - USD ($) $ in Millions	Dec. 31, 2024	Dec. 31, 2023
Fair Value, Financial Instruments [Line Items]
Total cash equivalents	$ 571	$ 190
Amortized Cost	230	457
Gross Unrealized Gains	0	2
Gross Unrealized Losses	(3)	(3)
Fair Value	(227)	(456)
Cash and Cash Equivalents
Fair Value, Financial Instruments [Line Items]
Total cash equivalents	257	101
Fair Value	0	0
Investments
Fair Value, Financial Instruments [Line Items]
Total cash equivalents	0	0
Fair Value	0	(208)
Restricted Cash, Cash Equivalents and Investments
Fair Value, Financial Instruments [Line Items]
Total cash equivalents	314	89
Fair Value	(227)	(248)
Asset-backed securities | Level 2
Fair Value, Financial Instruments [Line Items]
Amortized Cost	0	41
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	(1)
Fair Value	0	(40)
Asset-backed securities | Level 2 | Cash and Cash Equivalents
Fair Value, Financial Instruments [Line Items]
Fair Value	0	0
Asset-backed securities | Level 2 | Investments
Fair Value, Financial Instruments [Line Items]
Fair Value	0	(40)
Asset-backed securities | Level 2 | Restricted Cash, Cash Equivalents and Investments
Fair Value, Financial Instruments [Line Items]
Fair Value	0	0
Corporate bonds | Level 2
Fair Value, Financial Instruments [Line Items]
Amortized Cost	35	135
Gross Unrealized Gains	0	1
Gross Unrealized Losses	0	0
Fair Value	(35)	(136)
Corporate bonds | Level 2 | Cash and Cash Equivalents
Fair Value, Financial Instruments [Line Items]
Fair Value	0	0
Corporate bonds | Level 2 | Investments
Fair Value, Financial Instruments [Line Items]
Fair Value	0	(103)
Corporate bonds | Level 2 | Restricted Cash, Cash Equivalents and Investments
Fair Value, Financial Instruments [Line Items]
Fair Value	(35)	(33)
Agency securities | Level 2
Fair Value, Financial Instruments [Line Items]
Amortized Cost	18	40
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(1)	(1)
Fair Value	(17)	(39)
Agency securities | Level 2 | Cash and Cash Equivalents
Fair Value, Financial Instruments [Line Items]
Fair Value	0	0
Agency securities | Level 2 | Investments
Fair Value, Financial Instruments [Line Items]
Fair Value	0	(10)
Agency securities | Level 2 | Restricted Cash, Cash Equivalents and Investments
Fair Value, Financial Instruments [Line Items]
Fair Value	(17)	(29)
U.S. treasuries | Level 2
Fair Value, Financial Instruments [Line Items]
Amortized Cost	176	231
Gross Unrealized Gains	0	1
Gross Unrealized Losses	(2)	(1)
Fair Value	(174)	(231)
U.S. treasuries | Level 2 | Cash and Cash Equivalents
Fair Value, Financial Instruments [Line Items]
Fair Value	0	0
U.S. treasuries | Level 2 | Investments
Fair Value, Financial Instruments [Line Items]
Fair Value	0	(47)
U.S. treasuries | Level 2 | Restricted Cash, Cash Equivalents and Investments
Fair Value, Financial Instruments [Line Items]
Fair Value	(174)	(184)
Certificate of deposit | Level 2
Fair Value, Financial Instruments [Line Items]
Amortized Cost	1	2
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Fair Value	(1)	(2)
Certificate of deposit | Level 2 | Cash and Cash Equivalents
Fair Value, Financial Instruments [Line Items]
Fair Value	0	0
Certificate of deposit | Level 2 | Investments
Fair Value, Financial Instruments [Line Items]
Fair Value	0	0
Certificate of deposit | Level 2 | Restricted Cash, Cash Equivalents and Investments
Fair Value, Financial Instruments [Line Items]
Fair Value	(1)	(2)
Other debt securities | Level 2
Fair Value, Financial Instruments [Line Items]
Amortized Cost	0	8
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Fair Value	0	(8)
Other debt securities | Level 2 | Cash and Cash Equivalents
Fair Value, Financial Instruments [Line Items]
Fair Value	0	0
Other debt securities | Level 2 | Investments
Fair Value, Financial Instruments [Line Items]
Fair Value	0	(8)
Other debt securities | Level 2 | Restricted Cash, Cash Equivalents and Investments
Fair Value, Financial Instruments [Line Items]
Fair Value	0	0
Money market mutual funds | Level 1
Fair Value, Financial Instruments [Line Items]
Total cash equivalents	570	183
Money market mutual funds | Level 1 | Cash and Cash Equivalents
Fair Value, Financial Instruments [Line Items]
Total cash equivalents	257	96
Money market mutual funds | Level 1 | Investments
Fair Value, Financial Instruments [Line Items]
Total cash equivalents	0	0
Money market mutual funds | Level 1 | Restricted Cash, Cash Equivalents and Investments
Fair Value, Financial Instruments [Line Items]
Total cash equivalents	313	87
U.S. treasuries | Level 2
Fair Value, Financial Instruments [Line Items]
Total cash equivalents	1	7
U.S. treasuries | Level 2 | Cash and Cash Equivalents
Fair Value, Financial Instruments [Line Items]
Total cash equivalents	0	5
U.S. treasuries | Level 2 | Investments
Fair Value, Financial Instruments [Line Items]
Total cash equivalents	0	0
U.S. treasuries | Level 2 | Restricted Cash, Cash Equivalents and Investments
Fair Value, Financial Instruments [Line Items]
Total cash equivalents	$ 1	$ 2

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- Definition

Amount, before tax, of unrealized gain in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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