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Fair Value Measurements - Assets and Liabilities Not Measured at Fair Value (Details) - USD ($) $ in Thousands | Dec. 31, 2022 | Dec. 31, 2021 | Dec. 31, 2020
--- | --- | --- | ---
Senior Notes | 5.75% Senior Notes due 2023 |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Stated interest rate (in hundredths) | 5.75% |  |
Senior Notes | 5.25% Senior Notes due 2028 |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Stated interest rate (in hundredths) | 5.25% |  |
9% Convertible Junior Subordinated Debentures due 2063 |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Stated interest rate (in hundredths) | 9.00% | 9.00% | 9.00%
Carrying Value |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Other invested assets | $ 850 | $ 3,100 |
FHLB Advance | 0 | 155,000 |
9% Debentures | 21,086 | 110,204 |
Total financial liabilities | 662,810 | 1,146,712 |
Carrying Value | Senior Notes | 5.75% Senior Notes due 2023 |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Senior Notes | 0 | 241,255 |
Carrying Value | Senior Notes | 5.25% Senior Notes due 2028 |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Senior Notes | 641,724 | 640,253 |
Fair Value | Significant Other Observable Inputs (Level 2) |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Other invested assets | 850 | 3,100 |
FHLB Advance | 0 | 157,585 |
9% Debentures | 28,085 | 151,000 |
Total financial liabilities | 629,023 | 1,251,673 |
Fair Value | Significant Other Observable Inputs (Level 2) | Senior Notes | 5.75% Senior Notes due 2023 |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Senior Notes | 0 | 256,213 |
Fair Value | Significant Other Observable Inputs (Level 2) | Senior Notes | 5.25% Senior Notes due 2028 |  |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |  |
Senior Notes | $ 600,938 | $ 686,875 |

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