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Debt - Debt Outstanding (Details) € in Millions, $ in Millions | Dec. 31, 2023 USD ($) | Dec. 31, 2023 EUR (€) | Dec. 31, 2022 USD ($) | Dec. 31, 2021 USD ($) | Dec. 31, 2020 USD ($)
--- | --- | --- | --- | --- | ---
Debt Instrument |  |  |  |  |
Long-term debt, gross | $ 578.9 |  |  |  |
Carrying Value | 564.6 |  | $ 575.2 |  |
HG Global Senior Notes |  |  |  |  |
Debt Instrument |  |  |  |  |
Carrying Value | 146.9 |  | 146.5 |  |
Ark 2007 Subordinated Notes |  |  |  |  |
Debt Instrument |  |  |  |  |
Carrying Value | 30.0 |  | 30.0 |  |
Ark 2021 Subordinated Notes |  |  |  |  |
Debt Instrument |  |  |  |  |
Carrying Value | 155.5 |  | 153.7 |  |
Kudu Credit Facility |  |  |  |  |
Debt Instrument |  |  |  |  |
Carrying Value | 203.8 |  | 208.3 |  |
Other Operations debt |  |  |  |  |
Debt Instrument |  |  |  |  |
Carrying Value | 28.4 |  | 36.7 |  |
Senior Notes | HG Global Senior Notes |  |  |  |  |
Debt Instrument |  |  |  |  |
Long-term debt, gross | 150.0 |  | 150.0 |  |
Unamortized discount and issuance cost | (3.1) |  | (3.5) |  |
Carrying Value | $ 146.9 |  | $ 146.5 |  |
Effective yield (as a percent) | 11.90% | 11.90% | 8.90% |  |
Subordinated Debt | Ark |  |  |  |  |
Debt Instrument |  |  |  |  |
Carrying Value | $ 185.5 |  | $ 183.7 |  |
Effective yield (as a percent) | 11.00% | 11.00% | 7.60% |  |
Subordinated Debt | Ark 2007 Subordinated Notes |  |  |  |  |
Debt Instrument |  |  |  |  |
Long-term debt, gross | $ 30.0 |  | $ 30.0 |  |
Subordinated Debt | Ark 2021 Subordinated Notes |  |  |  |  |
Debt Instrument |  |  |  |  |
Unamortized issuance cost | (4.2) |  | (4.6) |  |
Carrying Value | 155.5 |  | 153.7 |  |
Subordinated Debt | Ark 2021 Subordinated Notes, Tranche 1 |  |  |  |  |
Debt Instrument |  |  |  |  |
Long-term debt, gross | 42.7 | € 39.1 | 41.3 |  |
Subordinated Debt | Ark 2021 Subordinated Notes, Tranche 2 |  |  |  |  |
Debt Instrument |  |  |  |  |
Long-term debt, gross | 47.0 |  | 47.0 |  |
Subordinated Debt | Ark 2021 Subordinated Notes, Tranche 3 |  |  |  |  |
Debt Instrument |  |  |  |  |
Long-term debt, gross | 70.0 |  | 70.0 |  |
Secured Debt | Kudu Credit Facility |  |  |  |  |
Debt Instrument |  |  |  |  |
Long-term debt, gross | 210.3 |  | 215.2 |  |
Unamortized issuance cost | (6.5) |  | (6.9) |  |
Carrying Value | $ 210.3 |  | $ 215.2 | $ 225.4 | $ 0.0
Effective yield (as a percent) | 10.10% | 10.10% | 6.10% |  |
Secured Debt | Other Operations debt |  |  |  |  |
Debt Instrument |  |  |  |  |
Long-term debt, gross | $ 28.9 |  | $ 37.4 |  |
Unamortized issuance cost | $ (0.5) |  | $ (0.7) |  |
Effective yield (as a percent) | 10.20% | 10.20% | 6.60% |  |

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