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Debt - Ark Subordinated Notes Narrative (Details) |  |  |  | 1 Months Ended | 3 Months Ended |  |  |  |
--- | --- | --- | --- | --- | --- | --- | --- | --- | ---
Sep. 08, 2021 USD ($) | Aug. 11, 2021 USD ($) | Jul. 13, 2021 USD ($) | Mar. 31, 2007 USD ($) | Sep. 30, 2021 USD ($) | Dec. 31, 2021 USD ($) | Dec. 31, 2021 EUR (€) | Jul. 13, 2021 EUR (€) | Dec. 31, 2020 USD ($) | Mar. 31, 2007 EUR (€)
Debt Instrument |  |  |  |  |  |  |  |  |  |
Debt |  |  |  |  |  | $ 693,000,000.0 |  |  | $ 376,400,000 |
Unsecured Subordinated Debt | Group Ark Insurance Limited |  |  |  |  |  |  |  |  |  |
Debt Instrument |  |  |  |  |  |  |  |  |  |
Proceeds from borrowings |  |  |  |  | $ 157,800,000 |  |  |  |  |
Unsecured Subordinated Debt | Ark | Group Ark Insurance Limited |  |  |  |  |  |  |  |  |  |
Debt Instrument |  |  |  |  |  |  |  |  |  |
Notes issued |  |  |  |  | $ 163,300,000 |  |  |  |  |
Ark 2007 Notes Tranche 1 | Ark Subordinated Notes |  |  |  |  |  |  |  |  |  |
Debt Instrument |  |  |  |  |  |  |  |  |  |
Long-term debt, gross |  |  |  |  |  | 30,000,000.0 |  |  |  |
Ark 2007 Notes Tranche 2 | Ark Subordinated Notes |  |  |  |  |  |  |  |  |  |
Debt Instrument |  |  |  |  |  |  |  |  |  |
Long-term debt, gross |  |  |  |  |  | 0 |  |  |  |
Ark 2021 Notes Tranche 1 |  |  |  |  |  |  |  |  |  |
Debt Instrument |  |  |  |  |  |  |  |  |  |
Long-term debt, gross | € |  |  |  |  |  |  | € 39,100,000 |  |  |
Ark 2021 Notes Tranche 1 | Ark Subordinated Notes |  |  |  |  |  |  |  |  |  |
Debt Instrument |  |  |  |  |  |  |  |  |  |
Long-term debt, gross |  |  |  |  |  | 44,200,000 |  |  |  |
Ark 2021 Notes Tranche 1 | Unsecured Subordinated Debt | Group Ark Insurance Limited |  |  |  |  |  |  |  |  |  |
Debt Instrument |  |  |  |  |  |  |  |  |  |
Notes issued |  |  | $ 46,300,000 |  |  |  |  | € 39,100,000 |  |
Ark 2021 Notes Tranche 1 | Unsecured Subordinated Debt | EURIBOR | Group Ark Insurance Limited |  |  |  |  |  |  |  |  |  |
Debt Instrument |  |  |  |  |  |  |  |  |  |
Basis spread on variable rate |  |  | 5.75% |  |  |  |  |  |  |
Ark 2021 Notes Tranche 2 | Ark Subordinated Notes |  |  |  |  |  |  |  |  |  |
Debt Instrument |  |  |  |  |  |  |  |  |  |
Long-term debt, gross |  |  |  |  |  | 47,000,000 |  |  |  |
Ark 2021 Notes Tranche 2 | Unsecured Subordinated Debt | Group Ark Insurance Limited |  |  |  |  |  |  |  |  |  |
Debt Instrument |  |  |  |  |  |  |  |  |  |
Notes issued |  | $ 47,000,000 |  |  |  |  |  |  |  |
Ark 2021 Notes Tranche 2 | Unsecured Subordinated Debt | United States Dollar London Interbank Offered Rate LIBOR | Group Ark Insurance Limited |  |  |  |  |  |  |  |  |  |
Debt Instrument |  |  |  |  |  |  |  |  |  |
Basis spread on variable rate |  | 5.75% |  |  |  |  |  |  |  |
Ark 2021 Notes Tranche 3 | Ark Subordinated Notes |  |  |  |  |  |  |  |  |  |
Debt Instrument |  |  |  |  |  |  |  |  |  |
Long-term debt, gross |  |  |  |  |  | 70,000,000.0 |  |  |  |
Ark 2021 Notes Tranche 3 | Unsecured Subordinated Debt | Group Ark Insurance Limited |  |  |  |  |  |  |  |  |  |
Debt Instrument |  |  |  |  |  |  |  |  |  |
Notes issued | $ 70,000,000 |  |  |  |  |  |  |  |  |
Additional interest rate | 1.00% |  |  |  |  |  |  |  |  |
Solvency capital requirement | 120.00% |  |  |  |  |  |  |  |  |
Debt to capital requirement | 40.00% |  |  |  |  |  |  |  |  |
Ark 2021 Notes Tranche 3 | Unsecured Subordinated Debt | United States Dollar London Interbank Offered Rate LIBOR | Group Ark Insurance Limited |  |  |  |  |  |  |  |  |  |
Debt Instrument |  |  |  |  |  |  |  |  |  |
Basis spread on variable rate | 6.10% |  |  |  |  |  |  |  |  |
Ark | Ark 2007 Notes Tranche 1 | Junior Notes |  |  |  |  |  |  |  |  |  |
Debt Instrument |  |  |  |  |  |  |  |  |  |
Long-term line of credit |  |  |  | $ 30,000,000 |  |  |  |  |  |
Debt |  |  |  |  |  | 30,000,000 |  |  |  |
Ark | Ark 2007 Notes Tranche 1 | Junior Notes | United States Dollar London Interbank Offered Rate LIBOR |  |  |  |  |  |  |  |  |  |
Debt Instrument |  |  |  |  |  |  |  |  |  |
Basis spread on variable rate |  |  |  | 4.60% |  |  |  |  |  |
Ark | Ark 2007 Notes Tranche 2 | Junior Notes |  |  |  |  |  |  |  |  |  |
Debt Instrument |  |  |  |  |  |  |  |  |  |
Long-term line of credit | € |  |  |  |  |  |  |  |  |  | € 12,000,000
Debt |  |  |  |  |  | $ 13,500,000 | € 12,000,000 |  |  |
Ark | Ark 2007 Notes Tranche 2 | Junior Notes | EURIBOR |  |  |  |  |  |  |  |  |  |
Debt Instrument |  |  |  |  |  |  |  |  |  |
Basis spread on variable rate |  |  |  | 4.60% |  |  |  |  |  |

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