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Condensed Financial Information of Registrant Condensed Financial Information of Registrant (Narratives) (Details) |  |  | 3 Months Ended | 12 Months Ended |  |
--- | --- | --- | --- | --- | --- | ---
Nov. 18, 2022 USD ($) | Mar. 08, 2017 USD ($) | Feb. 14, 2023 USD ($) | Dec. 31, 2022 USD ($) | Dec. 31, 2021 USD ($) | Dec. 31, 2020 USD ($) | Mar. 31, 2021 USD ($) | Mar. 29, 2017 USD ($)
Condensed Financial Statements, Captions [Line Items] |  |  |  |  |  |  |  |
Capital distribution from subsidiaries |  |  |  | $ 2,900,000 | $ 5,200,000 | $ 12,100,000 |  |
Proceeds from dividends received |  |  |  | 0 | 191,000,000 | 121,000,000 |  |
Payments of ordinary dividends |  |  |  | 0 | 191,000,000 | 121,000,000 |  |
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 | $ 200,000,000 |  |  |  |  |  | $ 75,000,000 | $ 50,000,000
Undrawn portion of credit facility |  |  |  | 175,000,000 |  |  |  |
Drawn down amount under credit facility |  |  |  | 25,000,000 |  |  |  |
Revolving Credit Facility | Unsecured Notes Two | Subsequent Event |  |  |  |  |  |  |  |
Condensed Financial Statements, Captions [Line Items] |  |  |  |  |  |  |  |
Interest rate, effective percentage |  |  | 5.68% |  |  |  |  |
Drawn down amount under credit facility |  |  | $ 25,000,000 |  |  |  |  |
Unsecured notes | 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% |  |  |  |  |  |
Unsecured notes | Unsecured Notes One | Notes payable |  |  |  |  |  |  |  |
Condensed Financial Statements, Captions [Line Items] |  |  |  |  |  |  |  |
Unsecured debt |  | $ 375,000,000 |  | $ 375,000,000 | 375,000,000 |  |  |
Interest rate, stated percentage |  |  |  | 4.40% |  |  |  |
Unsecured notes | Unsecured Notes Two | Notes payable |  |  |  |  |  |  |  |
Condensed Financial Statements, Captions [Line Items] |  |  |  |  |  |  |  |
Unsecured debt |  |  |  | $ 25,000,000 | 0 |  |  |
Minimum | Revolving Credit Facility | Unsecured Notes Two |  |  |  |  |  |  |  |
Condensed Financial Statements, Captions [Line Items] |  |  |  |  |  |  |  |
Commitment fee on undrawn portion of facility | 0.125% |  |  | 0.15% |  |  |  |
Minimum | Revolving Credit Facility | Unsecured Notes Two | Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate |  |  |  |  |  |  |  |
Condensed Financial Statements, Captions [Line Items] |  |  |  |  |  |  |  |
Debt to total capital ratio | 0.30 |  |  |  |  |  |  |
Minimum | Unsecured notes | Unsecured Notes Two | Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate | Notes payable |  |  |  |  |  |  |  |
Condensed Financial Statements, Captions [Line Items] |  |  |  |  |  |  |  |
Basis spread on variable rate | 1.125% |  |  |  |  |  |  |
Maximum | Revolving Credit Facility | Unsecured Notes Two |  |  |  |  |  |  |  |
Condensed Financial Statements, Captions [Line Items] |  |  |  |  |  |  |  |
Debt to total capital ratio |  |  |  | 0.208 |  |  |  |
Commitment fee on undrawn portion of facility | 0.225% |  |  |  |  |  |  |
Maximum | Revolving Credit Facility | Unsecured Notes Two | Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate |  |  |  |  |  |  |  |
Condensed Financial Statements, Captions [Line Items] |  |  |  |  |  |  |  |
Debt to total capital ratio | 0.20 |  |  |  |  |  |  |
Maximum | Unsecured notes | Unsecured Notes Two | Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate | Notes payable |  |  |  |  |  |  |  |
Condensed Financial Statements, Captions [Line Items] |  |  |  |  |  |  |  |
Basis spread on variable rate | 1.50% |  |  |  |  |  |  |
Parent Company |  |  |  |  |  |  |  |
Condensed Financial Statements, Captions [Line Items] |  |  |  |  |  |  |  |
Capital distribution from subsidiaries |  |  |  | $ 3,431,433 | 0 | 0 |  |
Payments for contributions to subsidiaries |  |  |  | $ 0 | $ 0 | $ 30,000,000 |  |

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