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Debt - Debt Outstanding (Details) € in Millions | 12 Months Ended |  |  |  |  |
--- | --- | --- | --- | --- | --- | ---
Dec. 31, 2021 USD ($) | Dec. 31, 2020 USD ($) | Dec. 31, 2021 EUR (€) | Jun. 02, 2021 USD ($) | Apr. 07, 2020 USD ($) | Dec. 31, 2019 USD ($) | Dec. 31, 2018 USD ($)
Debt Instrument |  |  |  |  |  |  |
Total debt | $ 693,000,000.0 | $ 376,400,000 |  |  |  |  |
Weighted average interest rate | 6.50% | 7.00% |  |  |  |  |
Ark Subordinated Notes |  |  |  |  |  |  |
Debt Instrument |  |  |  |  |  |  |
Unamortized issuance cost | $ (5,300,000) |  |  |  |  |  |
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 2007 Notes | Ark Subordinated Notes |  |  |  |  |  |  |
Debt Instrument |  |  |  |  |  |  |
Total debt | 30,000,000.0 |  |  |  |  |  |
Ark 2021 Notes Tranche 1 |  |  |  |  |  |  |
Debt Instrument |  |  |  |  |  |  |
Long-term debt, gross | € |  |  | € 39.1 |  |  |  |
Ark 2021 Notes Tranche 1 | Ark Subordinated Notes |  |  |  |  |  |  |
Debt Instrument |  |  |  |  |  |  |
Long-term debt, gross | 44,200,000 |  |  |  |  |  |
Ark 2021 Notes Tranche 2 | Ark Subordinated Notes |  |  |  |  |  |  |
Debt Instrument |  |  |  |  |  |  |
Long-term debt, gross | 47,000,000 |  |  |  |  |  |
Ark 2021 Notes Tranche 3 | Ark Subordinated Notes |  |  |  |  |  |  |
Debt Instrument |  |  |  |  |  |  |
Long-term debt, gross | 70,000,000.0 |  |  |  |  |  |
Ark 2021 Notes | Ark Subordinated Notes |  |  |  |  |  |  |
Debt Instrument |  |  |  |  |  |  |
Total debt | $ 155,900,000 |  |  |  |  |  |
Ark |  |  |  |  |  |  |
Debt Instrument |  |  |  |  |  |  |
Effective yield (as a percent) | 6.90% |  | 6.90% |  |  |  |
Ark | Ark Subordinated Notes |  |  |  |  |  |  |
Debt Instrument |  |  |  |  |  |  |
Total debt | $ 185,900,000 |  |  |  |  |  |
NSM Bank Facility |  |  |  |  |  |  |
Debt Instrument |  |  |  |  |  |  |
Effective yield (as a percent) | 8.20% | 8.40% | 8.20% |  |  |  |
NSM |  |  |  |  |  |  |
Debt Instrument |  |  |  |  |  |  |
Total debt | $ 272,100,000 | $ 272,600,000 |  |  |  |  |
NSM | NSM Bank Facility |  |  |  |  |  |  |
Debt Instrument |  |  |  |  |  |  |
Total debt | 277,600,000 | 277,400,000 |  |  |  | $ 221,300,000 | $ 180,400,000
Debt instrument at face value | 274,100,000 |  |  |  |  |  |
Kudu | Kudu Bank Facility |  |  |  |  |  |  |
Debt Instrument |  |  |  |  |  |  |
Total debt |  | 86,300,000 |  |  |  |  |
Kudu | Kudu Credit Facility |  |  |  |  |  |  |
Debt Instrument |  |  |  |  |  |  |
Total debt | 218,200,000 |  |  |  |  |  |
Other Operations | Other |  |  |  |  |  |  |
Debt Instrument |  |  |  |  |  |  |
Total debt | $ 16,800,000 |  |  |  |  |  |
Term Loan | Kudu Credit Facility |  |  |  |  |  |  |
Debt Instrument |  |  |  |  |  |  |
Effective yield (as a percent) | 4.30% |  | 4.30% |  |  |  |
Term Loan | NSM | NSM Bank Facility |  |  |  |  |  |  |
Debt Instrument |  |  |  |  |  |  |
Total debt | $ 271,200,000 | 271,300,000 |  |  |  |  |
Unamortized issuance cost | (6,400,000) | (6,100,000) |  |  |  |  |
Debt instrument at face value | $ 277,600,000 | $ 277,400,000 |  | $ 50,000,000 | $ 276,400,000 |  |
Effective yield (as a percent) | 7.30% | 7.50% | 7.30% |  |  |  |
Term Loan | NSM | Other NSM |  |  |  |  |  |  |
Debt Instrument |  |  |  |  |  |  |
Total debt | $ 900,000 | $ 1,300,000 |  |  |  |  |
Debt instrument at face value | $ 1,000,000 |  |  |  |  |  |
Effective yield (as a percent) | 2.90% | 2.50% | 2.90% |  |  |  |
Term Loan | Kudu | Kudu Bank Facility |  |  |  |  |  |  |
Debt Instrument |  |  |  |  |  |  |
Total debt | $ 0 | $ 89,200,000 |  |  |  | 57,000,000.0 | 0
Unamortized issuance cost |  | (2,900,000) |  |  |  |  |
Debt instrument at face value |  | $ 89,200,000 |  |  |  |  |
Effective yield (as a percent) |  | 8.30% |  |  |  |  |
Term Loan | Kudu | Kudu Credit Facility |  |  |  |  |  |  |
Debt Instrument |  |  |  |  |  |  |
Total debt | 225,400,000 | $ 0 |  |  |  | $ 0 | $ 0
Unamortized issuance cost | (7,200,000) |  |  |  |  |  |
Debt instrument at face value | 225,400,000 |  |  |  |  |  |
Term Loan | Other Operations | Other |  |  |  |  |  |  |
Debt Instrument |  |  |  |  |  |  |
Total debt |  | 17,500,000 |  |  |  |  |
Unamortized issuance cost | (300,000) | (500,000) |  |  |  |  |
Debt instrument at face value | $ 17,100,000 | $ 18,000,000.0 |  |  |  |  |
Term Loan | Other Operations | Other Debt |  |  |  |  |  |  |
Debt Instrument |  |  |  |  |  |  |
Effective yield (as a percent) | 7.50% | 7.40% | 7.50% |  |  |  |

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