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Condensed Financial Information of Registrant Condensed Financial Information of Registrant (Narratives) (Details) |  | 12 Months Ended |  |
--- | --- | --- | --- | ---
Mar. 08, 2017 USD ($) | Dec. 31, 2021 USD ($) | Dec. 31, 2020 USD ($) | Dec. 31, 2019 USD ($) | Mar. 31, 2021 USD ($) | Mar. 29, 2017 USD ($)
Condensed Financial Statements, Captions [Line Items] |  |  |  |  |  |
Capital distribution from subsidiaries |  | $ 5,200,000 | $ 12,100,000 | $ 5,200,000 |  |
Proceeds from dividends received |  | $ 191,000,000 | 121,000,000 | 114,431,433 |  |
Revolving Credit Facility |  |  |  |  |  |
Condensed Financial Statements, Captions [Line Items] |  |  |  |  |  |
Repayments of debt | $ 320,000,000 |  |  |  |  |
Revolving Credit Facility | Unsecured Notes Two |  |  |  |  |  |
Condensed Financial Statements, Captions [Line Items] |  |  |  |  |  |
Loan maximum borrowing capacity |  |  |  |  | $ 75,000,000 | $ 50,000,000
Unsecured Debt | Unsecured Notes One |  |  |  |  |  |
Condensed Financial Statements, Captions [Line Items] |  |  |  |  |  |
Interest rate, stated percentage | 4.40% |  |  |  |  |
Debt issuance costs | $ 3,400,000 |  |  |  |  |
Discount percent | 99.847% |  |  |  |  |
Interest rate, effective percentage | 4.45% |  |  |  |  |
Minimum | Revolving Credit Facility | Unsecured Notes Two |  |  |  |  |  |
Condensed Financial Statements, Captions [Line Items] |  |  |  |  |  |
Commitment fee on undrawn portion of facility |  | 0.125% |  |  |  |
Minimum | Revolving Credit Facility | Unsecured Notes Two | LIBOR |  |  |  |  |  |
Condensed Financial Statements, Captions [Line Items] |  |  |  |  |  |
Debt to total capital ratio |  |  |  |  | 0.30 |
Maximum | Revolving Credit Facility | Unsecured Notes Two |  |  |  |  |  |
Condensed Financial Statements, Captions [Line Items] |  |  |  |  |  |
Debt to total capital ratio |  | 0.149 |  |  |  |
Commitment fee on undrawn portion of facility |  | 0.225% |  |  |  |
Maximum | Revolving Credit Facility | Unsecured Notes Two | LIBOR |  |  |  |  |  |
Condensed Financial Statements, Captions [Line Items] |  |  |  |  |  |
Debt to total capital ratio |  |  |  |  | 0.20 |
Parent Company |  |  |  |  |  |
Condensed Financial Statements, Captions [Line Items] |  |  |  |  |  |
Capital distribution from subsidiaries |  | $ 0 | 0 | 30,068,567 |  |
Payments for contributions to subsidiaries |  | $ 0 | $ 30,000,000 | $ 125,000 |  |

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