Debt and letter of credit facilities - Debt Obligations (Details) - USD ($) $ in Millions |
Jun. 30, 2025 |
Dec. 31, 2024 |
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| Debt Instrument [Line Items] | ||
| Total debt | $ 678.4 | $ 639.1 |
| Senior Notes | 2024 Senior Notes | ||
| Debt Instrument [Line Items] | ||
| Debt, at face value | 400.0 | 400.0 |
| Unamortized discount | (4.6) | (5.2) |
| Total debt | $ 395.4 | $ 394.8 |
| Effective rate | 7.40% | 7.40% |
| Subordinated Notes | ||
| Debt Instrument [Line Items] | ||
| Debt, at face value | $ 288.6 | $ 249.2 |
| Unamortized discount | (5.6) | (4.9) |
| Total debt | $ 283.0 | $ 244.3 |
| Effective rate | 7.10% | 7.90% |
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- Definition Amount, before unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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- Definition Effective interest rate for the funds borrowed under the debt agreement considering interest compounding and original issue discount or premium. Reference 1: http://www.xbrl.org/2003/role/exampleRef
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- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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- Definition Amount, after accumulated amortization, of debt discount. Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
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- Definition Amount, after deduction of unamortized premium (discount) and debt issuance cost, of long-term debt. Excludes lease obligation. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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