Available-for-Sale Debt Securities - Additional Information (Detail) - USD ($) $ in Millions |
12 Months Ended | ||
|---|---|---|---|
Mar. 31, 2026 |
Mar. 31, 2025 |
Mar. 31, 2024 |
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| Investments, Debt and Equity Securities [Abstract] | |||
| Net realized gains (losses) on available-for-sale debt securities | $ 7.6 | $ (42.5) | $ (3.7) |
| Unrealized foreign exchange adjustments | 7.3 | (42.5) | $ (3.4) |
| Allowance for credit losses | 1.0 | 0.0 | |
| Accrued interest receivable | $ 21.1 | $ 31.2 | |
| Debt Securities, Available-for-Sale, Accrued Interest, after Allowance for Credit Loss, Statement of Financial Position [Extensible Enumeration] | Prepaid Expense, Current | Prepaid Expense, Current | |
| X | ||||||||||
- Definition Amount, after allowance for credit loss, of accrued interest on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale). Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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| X | ||||||||||
- Definition Indicates line item in statement of financial position that includes accrued interest, after allowance for credit loss, on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale). Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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| X | ||||||||||
- Definition Amount of allowance for credit loss on investment in debt security measured at amortized cost (held-to-maturity) and investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale). Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
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| X | ||||||||||
- Definition Amount of realized gain (loss) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale). Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
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| X | ||||||||||
- References No definition available.
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| X | ||||||||||
- Definition Unrealized foreign exchange adjustments. No definition available.
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