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Schedule I: Summary of Investments - Other Than Investments in Related Parties (Parenthetical) (Details) - USD ($) $ in Thousands | Dec. 31, 2024 | Dec. 31, 2023
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SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items] |  |
Loaned securities | $ 139,121 | $ 203,693
Reinvested cash collateral held under securities lending agreements | 125,723 | $ 149,364
Loaned securities |  |
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items] |  |
Loaned securities | 130,000 |
Trading securities |  |
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items] |  |
Reinvested cash collateral held under securities lending agreements | 126,000 |
Equity securities | Loaned securities |  |
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items] |  |
Loaned securities | 9,000 |
Short-term investments | Loaned securities |  |
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items] |  |
Loaned securities | $ 464 |

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- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Name Regulation S-X (SX) -Number 210 -Section 12 -Subsection 15 -Publisher SEC Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 946 -SubTopic 320 -Name Accounting Standards Codification -Section S99 -Paragraph 7 -Subparagraph (SX 210.12-15) -Publisher FASB -URI https://asc.fasb.org/1943274/2147477271/946-320-S99-7 + Details
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