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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 | Jun. 30, 2025 | Dec. 31, 2024
--- | --- | ---
Debt Securities |  |
Cash equivalents: | $ 171 | $ 571
Amortized Cost | 205 | 230
Gross Unrealized Gains | 1 | 0
Gross Unrealized Losses | 0 | (3)
Fair Value | 206 | 227
Cash and Cash Equivalents |  |
Debt Securities |  |
Cash equivalents: | 31 | 257
Fair Value | 0 | 0
Investments |  |
Debt Securities |  |
Cash equivalents: | 0 | 0
Fair Value | 0 | 0
Restricted Cash, Cash Equivalents and Investments |  |
Debt Securities |  |
Cash equivalents: | 140 | 314
Fair Value | 206 | 227
Corporate bonds | Level 2 |  |
Debt Securities |  |
Amortized Cost | 34 | 35
Gross Unrealized Gains | 0 |
Gross Unrealized Losses | 0 | 0
Fair Value | 34 | 35
Corporate bonds | Level 2 | Cash and Cash Equivalents |  |
Debt Securities |  |
Fair Value | 0 | 0
Corporate bonds | Level 2 | Investments |  |
Debt Securities |  |
Fair Value | 0 |
Corporate bonds | Level 2 | Restricted Cash, Cash Equivalents and Investments |  |
Debt Securities |  |
Fair Value | 34 | 35
Agency securities | Level 2 |  |
Debt Securities |  |
Amortized Cost | 13 | 18
Gross Unrealized Gains | 0 | 0
Gross Unrealized Losses | 0 | (1)
Fair Value | 13 | 17
Agency securities | Level 2 | Cash and Cash Equivalents |  |
Debt Securities |  |
Fair Value | 0 | 0
Agency securities | Level 2 | Investments |  |
Debt Securities |  |
Fair Value | 0 |
Agency securities | Level 2 | Restricted Cash, Cash Equivalents and Investments |  |
Debt Securities |  |
Fair Value | 13 | 17
U.S. treasuries | Level 2 |  |
Debt Securities |  |
Amortized Cost | 158 | 176
Gross Unrealized Gains | 1 |
Gross Unrealized Losses | 0 | (2)
Fair Value | 159 | 174
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 | 0 |
U.S. treasuries | Level 2 | Restricted Cash, Cash Equivalents and Investments |  |
Debt Securities |  |
Fair Value | 159 | 174
Certificate of deposit | Level 2 |  |
Debt Securities |  |
Amortized Cost |  | 1
Gross Unrealized Gains |  | 0
Gross Unrealized Losses |  | 0
Fair Value |  | 1
Certificate of deposit | Level 2 | Cash and Cash Equivalents |  |
Debt Securities |  |
Fair Value |  | 0
Certificate of deposit | Level 2 | Investments |  |
Debt Securities |  |
Fair Value |  | 0
Certificate of deposit | Level 2 | Restricted Cash, Cash Equivalents and Investments |  |
Debt Securities |  |
Fair Value |  | 1
Money market mutual funds | Level 1 |  |
Debt Securities |  |
Cash equivalents: | 164 | 570
Money market mutual funds | Level 1 | Cash and Cash Equivalents |  |
Debt Securities |  |
Cash equivalents: | 31 | 257
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: | 133 | 313
U.S. treasuries | Level 2 |  |
Debt Securities |  |
Cash equivalents: | 7 | 1
U.S. treasuries | Level 2 | Cash and Cash Equivalents |  |
Debt Securities |  |
Cash equivalents: | 0 | 0
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: | $ 7 | $ 1

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