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Fair Value Measurements - Assets and Liabilities Not Measured at Fair Value (Details) - USD ($) $ in Thousands | Mar. 31, 2019 | Dec. 31, 2018
--- | --- | ---
Carrying Value |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Other invested assets | $ 3,100 | $ 3,100
FHLB Advance | 155,000 | 155,000
5.75% Senior Notes | 420,002 | 419,713
9% Convertible Junior Subordinated Debentures | 256,872 | 256,872
Total financial liabilities | 831,874 | 831,585
Fair Value | Significant Other Observable Inputs (Level 2) |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Other invested assets | 3,100 | 3,100
FHLB Advance | 153,133 | 150,551
5.75% Senior Notes | 449,387 | 425,791
9% Convertible Junior Subordinated Debentures | 332,580 | 338,069
Total financial liabilities | $ 935,100 | $ 914,411
Senior Notes | 5.75% Senior Notes Due 2023 |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Stated interest rate | 5.75% |
9% Convertible Junior Subordinated Debentures |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Stated interest rate | 9.00% |

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