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Fair Value Measurements - Schedule of Quantitative Information of Our Financial Assets and Liabilities That Were Disclosed at Fair Value (Details) - USD ($) $ in Thousands | Sep. 30, 2024 | Dec. 31, 2023
--- | --- | ---
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Fixed income securities, held-to-maturity - fair value | $ 21,440 | $ 21,923
Commercial mortgage loans, fair value | 218,599 | 178,913
Long-term debt, fair value | 517,310 | 503,805
Corporate securities |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Fixed income securities, held-to-maturity - fair value | 21,440 | 21,923
Quoted Prices in  Active Markets for Identical Assets/ Liabilities (Level 1) |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Fixed income securities, held-to-maturity - fair value | 0 | 0
Commercial mortgage loans, fair value | 0 | 0
Long-term debt, fair value | 0 | 0
Quoted Prices in  Active Markets for Identical Assets/ Liabilities (Level 1) | Corporate securities |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Fixed income securities, held-to-maturity - fair value | 0 | 0
Significant Other Observable Inputs (Level 2) |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Fixed income securities, held-to-maturity - fair value | 21,440 | 21,923
Commercial mortgage loans, fair value | 0 | 0
Long-term debt, fair value | 517,310 | 503,805
Significant Other Observable Inputs (Level 2) | Corporate securities |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Fixed income securities, held-to-maturity - fair value | 21,440 | 21,923
Significant Unobservable Inputs (Level 3) |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Fixed income securities, held-to-maturity - fair value | 0 | 0
Commercial mortgage loans, fair value | 218,599 | 178,913
Long-term debt, fair value | 0 | 0
Significant Unobservable Inputs (Level 3) | Corporate securities |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Fixed income securities, held-to-maturity - fair value | $ 0 | $ 0
7.25% Senior Notes |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Interest rate | 7.25% | 7.25%
Long-term debt, fair value | $ 54,828 | $ 53,047
7.25% Senior Notes | Quoted Prices in  Active Markets for Identical Assets/ Liabilities (Level 1) |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Long-term debt, fair value | 0 | 0
7.25% Senior Notes | Significant Other Observable Inputs (Level 2) |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Long-term debt, fair value | 54,828 | 53,047
7.25% Senior Notes | Significant Unobservable Inputs (Level 3) |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Long-term debt, fair value | $ 0 | $ 0
6.70% Senior Notes |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Interest rate | 6.70% | 6.70%
Long-term debt, fair value | $ 106,814 | $ 104,039
6.70% Senior Notes | Quoted Prices in  Active Markets for Identical Assets/ Liabilities (Level 1) |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Long-term debt, fair value | 0 | 0
6.70% Senior Notes | Significant Other Observable Inputs (Level 2) |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Long-term debt, fair value | 106,814 | 104,039
6.70% Senior Notes | Significant Unobservable Inputs (Level 3) |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Long-term debt, fair value | $ 0 | $ 0
5.375% Senior Notes |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Interest rate | 5.375% | 5.375%
Long-term debt, fair value | $ 296,608 | $ 288,787
5.375% Senior Notes | Quoted Prices in  Active Markets for Identical Assets/ Liabilities (Level 1) |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Long-term debt, fair value | 0 | 0
5.375% Senior Notes | Significant Other Observable Inputs (Level 2) |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Long-term debt, fair value | 296,608 | 288,787
5.375% Senior Notes | Significant Unobservable Inputs (Level 3) |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Long-term debt, fair value | $ 0 | $ 0
3.03% borrowings from FHLBI |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Interest rate | 3.03% | 3.03%
Long-term debt, fair value | $ 59,060 | $ 57,932
3.03% borrowings from FHLBI | Quoted Prices in  Active Markets for Identical Assets/ Liabilities (Level 1) |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Long-term debt, fair value | 0 | 0
3.03% borrowings from FHLBI | Significant Other Observable Inputs (Level 2) |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Long-term debt, fair value | 59,060 | 57,932
3.03% borrowings from FHLBI | Significant Unobservable Inputs (Level 3) |  |
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] |  |
Long-term debt, fair value | $ 0 | $ 0

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