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Investments - Additional Information (Detail) | 9 Months Ended |
--- | --- | ---
Sep. 30, 2024 USD ($) Entity ParntershipInvestments | Dec. 31, 2023 USD ($)
Schedule Of Available For Sale Securities [Line Items] |  |
Investments in a single issuer as a percentage of shareholders' equity | 1.70% | 2.10%
Number of limited partnership investments | ParntershipInvestments | 3 |
Fixed maturity securities with market value | $ 0 | $ 0
Investments in insurance enhanced bonds | $ 1,700,000 |
Insurance enhanced bonds as a percentage of total cash and invested assets | 0.10% |
Investments in collateralized mortgage obligations, commercial mortgage-backed securities and taxable municipal bonds | $ 1,700,000 |
Equity securities, at fair value | 12,347,000 | 16,508,000
Future Funding Commitments | 14,214,000 | 14,214,000
Limited partnership investments with carrying value of fair value | $ 29,500,000 | 38,200,000
Variable Interest Entity, Not Primary Beneficiary |  |
Schedule Of Available For Sale Securities [Line Items] |  |
Number of VIE's | Entity | 2 |
Ownership interest exceeds respective investments | 3.00% |
One of the Company's variable interest VIE's, invests in distressed securities and assets |  |
Schedule Of Available For Sale Securities [Line Items] |  |
Significant variable interest in carrying value of the non-consolidated VIE | $ 3,400,000 | 4,000,000
Future Funding Commitments | 14,200,000 | 14,200,000
Variable interest entities, maximum exposure to loss | 17,600,000 | 18,300,000
Second VIE that invests in REIT qualifying assets |  |
Schedule Of Available For Sale Securities [Line Items] |  |
Significant variable interest in carrying value of the non-consolidated VIE | 8,600,000 | 8,200,000
Variable interest entities, maximum exposure to loss | 8,600,000 | 8,200,000
Assured Guaranty Corporation |  |
Schedule Of Available For Sale Securities [Line Items] |  |
Investments in collateralized mortgage obligations, commercial mortgage-backed securities and taxable municipal bonds | 800,000 |
Ambac Financial Group |  |
Schedule Of Available For Sale Securities [Line Items] |  |
Investments in collateralized mortgage obligations, commercial mortgage-backed securities and taxable municipal bonds | 900,000 |
Other Assets |  |
Schedule Of Available For Sale Securities [Line Items] |  |
Accrued interest receivable related to fixed maturities | 3,500,000 | 7,500,000
Preferred Stock |  |
Schedule Of Available For Sale Securities [Line Items] |  |
Equity securities, at fair value | 12,300,000 | $ 16,500,000
U.S. Treasuries |  |
Schedule Of Available For Sale Securities [Line Items] |  |
Gross unrealized losses | 683,000 |
Obligations of States and Political Subdivisions |  |
Schedule Of Available For Sale Securities [Line Items] |  |
Gross unrealized losses | 634,000 |
Mortgage Backed Securities |  |
Schedule Of Available For Sale Securities [Line Items] |  |
Gross unrealized losses | 2,438,000 |
Asset-backed Securities |  |
Schedule Of Available For Sale Securities [Line Items] |  |
Gross unrealized losses | $ 2,810,000 |
Weighted average credit enhancement | 38.00% |
Commercial Mortgage-Backed Securities |  |
Schedule Of Available For Sale Securities [Line Items] |  |
Gross unrealized losses | $ 2,526,000 |
Weighted average credit enhancement | 44.00% |
Corporate Bonds |  |
Schedule Of Available For Sale Securities [Line Items] |  |
Gross unrealized losses | $ 2,777,000 |
Foreign Corporate Bonds |  |
Schedule Of Available For Sale Securities [Line Items] |  |
Gross unrealized losses | $ 1,604,000 |

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