Investments - Contractual Maturity (Details) - USD ($) $ in Millions |
Sep. 30, 2026 |
Dec. 31, 2025 |
|---|---|---|
| Amortized Cost | ||
| One year or less | $ 52.9 | |
| After one year through five years | 192.7 | |
| After five years through ten years | 106.3 | |
| After ten years | 3.9 | |
| Amortized Cost | 450.7 | $ 291.7 |
| Fair Value | ||
| One year or less | 52.7 | |
| After one year through five years | 187.9 | |
| After five years through ten years | 100.9 | |
| After ten years | 3.7 | |
| Fair Value | 436.3 | 293.4 |
| Residential mortgage-backed securities | ||
| Amortized Cost | ||
| Securities | 60.6 | |
| Amortized Cost | 60.6 | 38.2 |
| Fair Value | ||
| Securities | 57.0 | |
| Fair Value | 57.0 | 37.7 |
| Commercial mortgage-backed securities | ||
| Amortized Cost | ||
| Securities | 3.1 | |
| Amortized Cost | 3.1 | 5.2 |
| Fair Value | ||
| Securities | 2.9 | |
| Fair Value | 2.9 | 5.0 |
| Asset backed securities | ||
| Amortized Cost | ||
| Securities | 31.2 | |
| Amortized Cost | 31.2 | 20.4 |
| Fair Value | ||
| Securities | 31.2 | |
| Fair Value | $ 31.2 | $ 20.4 |
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- Definition Amortized cost of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), with single maturity date and allocated without single maturity date, maturing in sixth through tenth fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach). Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
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- Definition Fair value of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), with single maturity date and allocated without single maturity date, maturing in sixth through tenth fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach). Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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- Definition Amortized cost of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), with single maturity date and allocated without single maturity date, maturing in second through fifth fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach). Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
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- Definition Fair value of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), with single maturity date and allocated without single maturity date, maturing in second through fifth fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach). Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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- Definition Amortized cost of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), with single maturity date and allocated without single maturity date, maturing after tenth fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach). Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
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- Definition Fair value of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), with single maturity date and allocated without single maturity date, maturing after tenth fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach). Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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- References No definition available.
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- References No definition available.
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- Definition Amortized cost of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), with single maturity date and allocated without single maturity date, maturing in next fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach). Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
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- Definition Fair value of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), with single maturity date and allocated without single maturity date, maturing in next fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach). Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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- Definition Amortized cost of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), without single maturity date and not allocated over maturity grouping. Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
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- Definition Fair value of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), without single maturity date and not allocated over maturity grouping. Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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- Definition Amortized cost excluding accrued interest, after allowance for credit loss, of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), classified as noncurrent. Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
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- Definition Amount excluding accrued interest, of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), classified as noncurrent. Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
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