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Financial Instruments - Additional Information (Details) $ / shares in Units, shares in Millions, $ in Millions |  | 3 Months Ended | 9 Months Ended | 12 Months Ended |  |
--- | --- | --- | --- | --- | --- | ---
Jul. 02, 2024 $ / shares shares | Sep. 30, 2025 USD ($) | Sep. 30, 2024 USD ($) | Sep. 30, 2025 USD ($) | Sep. 30, 2024 USD ($) | Dec. 31, 2024 USD ($) | Jun. 30, 2025 USD ($) | Jul. 12, 2024 USD ($)
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |  |  |  |  |  |  |
Period to receive earnout shares |  |  |  | 7 years |  |  |  |
Fair value of seller earnouts |  |  |  | $ 2 |  | $ 51 |  |
(Gain) loss from change in fair value of seller earnouts |  | $ (19) | $ (3) | (49) | $ (32) |  |  |
Fair value of seller note |  | 0 |  | 0 |  | 50 | $ 0 |
(Gain) loss from change in fair value of financial instruments |  | (19) | (23) | 1 | (54) |  |  |
Discontinued Operations, Disposed of by Sale | Divested Business |  |  |  |  |  |  |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |  |  |  |  |  |  |
Aggregate principal amount, contingent consideration |  |  |  |  |  |  |  | $ 150
Fair value contingent consideration |  |  |  |  |  |  |  | $ 43
(Gain) loss from change in fair value of financial instruments |  | 0 | 20 | 50 | 20 |  |  |
Class A Common Stock |  |  |  |  |  |  |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |  |  |  |  |  |  |
Shares issued (in shares) | shares | 1.5 |  |  |  |  |  |  |
Price per share | $ / shares | $ 7.09 |  |  |  |  |  |  |
Class Z-A Common Stock |  |  |  |  |  |  |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |  |  |  |  |  |  |
Equity, contingent consideration at fair value |  | 0 |  | 0 |  | $ 0 |  |
Class Z Common Stock |  |  |  |  |  |  |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |  |  |  |  |  |  |
(Gain) loss from change in fair value of seller earnouts |  | $ 0 | $ 0 | $ 0 | $ (2) |  |  |
Maturity | Valuation, Income Approach | Level 3 |  |  |  |  |  |  |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |  |  |  |  |  |  |
Additional seller note, measurement basis |  |  |  | 4 years 9 months 10 days |  |  |  |
Seller earnouts liability |  |  |  |  |  |  |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |  |  |  |  |  |  |
Business combination, contingent consideration, liability expected holding period |  |  |  | 2 years 9 months |  |  |  |
Seller earnouts liability | Volatility |  |  |  |  |  |  |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |  |  |  |  |  |  |
Measurement Input |  | 0.3991 |  | 0.3991 |  |  |  |
Seller earnouts liability | Risk-free Interest Rate |  |  |  |  |  |  |  |
Fair Value Measurement Inputs and Valuation Techniques [Line Items] |  |  |  |  |  |  |  |
Measurement Input |  | 0.0358 |  | 0.0358 |  |  |  |

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