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Notes Payable (Schedule of Long-term Debt) (Details) |  |  | 6 Months Ended | 12 Months Ended |  |  |  |
--- | --- | --- | --- | --- | --- | --- | --- | ---
Jul. 24, 2025 USD ($) | Nov. 22, 2024 | Jun. 30, 2025 USD ($) | Dec. 31, 2024 USD ($) | Nov. 30, 2023 USD ($) | Nov. 18, 2022 USD ($) | Mar. 31, 2021 USD ($) | Mar. 08, 2017 USD ($)
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Interest rate (in percent) |  |  |  |  |  |  |  | 4.40%
Total principal amount |  |  | $ 575,000,000 | $ 575,000,000 |  |  |  |
Less unamortized discount and debt issuance costs |  |  | 673,000 | 872,000 |  |  |  |
Notes payable |  |  | 574,327,000 | 574,128,000 |  |  |  |
Debt issuance cost |  |  |  |  |  |  |  | $ 3,400,000
Debt instrument, discount percent |  |  |  |  |  |  |  | 99.847%
Effective interest rate |  |  |  |  |  |  |  | 4.45%
Unamortized debt issuance cost |  |  | 500,000 |  |  |  |  |
Unsecured Notes Two | Revolving Credit Facility |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Loan maximum borrowing capacity |  |  |  |  | $ 250,000,000 | $ 200,000,000 | $ 75,000,000 |
Drawn down amount under credit facility |  |  | 200,000,000 | 200,000,000 |  |  |  |
Unsecured Notes Two | Revolving Credit Facility | Consolidated Insurance Subsidiary |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Drawn down amount under credit facility contributed |  |  | 150,000,000 |  |  |  |  |
Unsecured Notes Two | Revolving Credit Facility | Subsequent Event |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Effective interest rate | 5.67% |  |  |  |  |  |  |
Drawn down amount under credit facility | $ 200,000,000 |  |  |  |  |  |  |
Remaining amount available to be drawn | $ 50,000,000 |  |  |  |  |  |  |
Unsecured notes |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Notes payable |  |  | $ 374,327,000 | 374,128,000 |  |  |  |
Unsecured notes | Notes payable | Level 2 | Unsecured Notes One |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Interest rate (in percent) |  |  | 4.40% |  |  |  |  |
Unsecured debt |  |  | $ 375,000,000 | 375,000,000 |  |  |  | $ 375,000,000
Unsecured notes | Notes payable | Level 2 | Unsecured Notes Two |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Unsecured debt |  |  | $ 200,000,000 | $ 200,000,000 |  |  |  |
Minimum | Unsecured Notes Two | Revolving Credit Facility |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Basis spread on variable rate |  |  | 1.125% |  |  |  |  |
Debt to total capital ratio |  | 0.20 |  |  |  |  |  |
Commitment fee on undrawn portion of facility |  | 0.125% | 0.15% |  |  |  |  |
Minimum | Unsecured notes | Notes payable | Level 2 | Unsecured Notes Two |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Basis spread on variable rate |  |  | 1.125% |  |  |  |  |
Maximum | Unsecured Notes Two | Revolving Credit Facility |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Debt to total capital ratio |  | 0.30 | 0.226 |  |  |  |  |
Commitment fee on undrawn portion of facility |  | 0.225% |  |  |  |  |  |
Maximum | Unsecured notes | Notes payable | Level 2 | Unsecured Notes Two |  |  |  |  |  |  |  |
Debt Instrument [Line Items] |  |  |  |  |  |  |  |
Basis spread on variable rate |  |  | 1.50% |  |  |  |  |

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