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Equity Investments - Narrative (Details) - USD ($) |  | 3 Months Ended | 6 Months Ended |
--- | --- | --- | --- | ---
Mar. 19, 2025 | Sep. 30, 2025 | Sep. 30, 2024 | Sep. 30, 2025 | Sep. 30, 2024 | Mar. 31, 2025
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |
Equity method investments under fair value option |  | $ 294,000,000 |  | $ 294,000,000 |  | $ 300,000,000
Gains (losses) on equity method investments |  | (4,000,000) | $ (12,000,000) | (5,000,000) | $ (12,000,000) |
Equity method investments under equity method |  | 17,000,000 |  | 17,000,000 |  | 16,000,000
Other non-current assets |  | 249,000,000 |  | 249,000,000 |  | 305,000,000
Prepaid expense and other assets |  | 346,000,000 |  | 346,000,000 |  | 256,000,000
Equity investments in publicly listed companies |  | 94,000,000 |  | 94,000,000 |  | 98,000,000
Gain (loss) in investments of publicly listed companies |  | (12,000,000) | 2,000,000 | (8,000,000) | 29,000,000 |
Non-marketable equity securities |  | 151,000,000 |  | 151,000,000 |  | 151,000,000
Gain (loss) in non-marketable equity securities |  | 0 | 0 | 1,000,000 | (3,000,000) |
Payments to acquire non-marketable preferred stock |  |  |  | 3,000,000 | 41,000,000 |
Dividends from equity investments |  | 2,500,000 | 1,000,000 | 3,500,000 | 1,100,000 |
Financial commitments to investees, off balance sheet |  | 27,000,000 |  | 27,000,000 |  | 28,100,000
Kigen (UK) Limited |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |
Non-marketable equity securities |  | 16,400,000 |  | 16,400,000 |  | 15,000,000
Payments to acquire non-marketable preferred stock |  |  |  | 1,400,000 |  |
Ampere | Loans receivable |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |
Other non-current assets |  |  |  |  |  | 33,800,000
Prepaid expense and other assets |  | 34,500,000 |  | 34,500,000 |  |
Acetone Limited |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |
Gains (losses) on equity method investments |  | 0 | (9,000,000) | 0 | (9,000,000) |
Equity method investments under equity method |  | 56,500,000 |  | 56,500,000 |  |
Ampere |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |
Gains (losses) on equity method investments |  | 0 | 0 | 0 | 0 |
Equity method investments under equity method |  | 143,400,000 |  | 143,400,000 |  | 143,400,000
Expected gross proceeds | $ 140,000,000 |  |  |  |  |
Publicly Listed Companies |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |
Equity investments in publicly listed companies |  | 93,900,000 |  | 93,900,000 |  | 97,900,000
Gain (loss) in investments of publicly listed companies |  | (11,600,000) | 1,900,000 | (7,800,000) | 28,900,000 |
Fair Value Measured at Net Asset Value Per Share |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |
Equity method investments under fair value option |  | 94,200,000 |  | 94,200,000 |  | 100,300,000
Gains (losses) on equity method investments |  | (3,500,000) | (2,400,000) | (5,500,000) | (2,800,000) |
Non-marketable equity securities |  | 16,900,000 |  | 16,900,000 |  | $ 15,700,000
Gain (loss) in non-marketable equity securities |  | $ (100,000) | $ 100,000 | $ 1,000,000 | $ (1,600,000) |

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