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Financial Instruments - Narrative (Details) - USD ($) $ in Millions | 3 Months Ended | 6 Months Ended |  |
--- | --- | --- | --- | ---
Sep. 30, 2025 | Sep. 30, 2024 | Sep. 30, 2025 | Sep. 30, 2024 | Mar. 31, 2025 | Dec. 31, 2021
Level 3 |  |  |  |  |  |
Financing Receivable, Allowance for Credit Loss [Line Items] |  |  |  |  |  |
Convertible loans receivable | $ 34.0 |  | $ 34.0 |  | $ 34.0 |
Convertible loans receivable | Level 3 |  |  |  |  |  |
Financing Receivable, Allowance for Credit Loss [Line Items] |  |  |  |  |  |
Fair value losses recognized in the Condensed Consolidated Income Statements | 0.0 | $ 0.0 | 0.0 | $ 1.0 |  |
Loans receivable |  |  |  |  |  |
Financing Receivable, Allowance for Credit Loss [Line Items] |  |  |  |  |  |
Loans and other receivables carried at amortized cost | 27.0 |  | 27.0 |  | 27.0 |
Arduino |  |  |  |  |  |
Financing Receivable, Allowance for Credit Loss [Line Items] |  |  |  |  |  |
Loans and other receivables carried at amortized cost | 16.9 |  | 16.9 |  | 16.6 |
Loan receivable, credit loss reversal | 16.8 |  |  |  |  |
Cerfe Labs, Inc. | Loans receivable |  |  |  |  |  |
Financing Receivable, Allowance for Credit Loss [Line Items] |  |  |  |  |  |
Loans and other receivables carried at amortized cost | $ 3.2 |  | $ 3.2 |  | $ 3.2 |
Loan term | 4 years |  | 4 years |  | 4 years |
Allia Limited | Loans receivable |  |  |  |  |  |
Financing Receivable, Allowance for Credit Loss [Line Items] |  |  |  |  |  |
Loans and other receivables carried at amortized cost | $ 7.4 |  | $ 7.4 |  | $ 7.1 |
Loan term | 5 years |  | 5 years |  | 5 years |
Ampere |  |  |  |  |  |
Financing Receivable, Allowance for Credit Loss [Line Items] |  |  |  |  |  |
Convertible loans receivable |  |  |  |  |  | $ 29.0
Ampere | Convertible loans receivable | Level 3 |  |  |  |  |  |
Financing Receivable, Allowance for Credit Loss [Line Items] |  |  |  |  |  |
Fair value losses recognized in the Condensed Consolidated Income Statements | $ 0.0 | $ 0.0 | $ 0.4 | $ 1.0 |  |

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