Schedule I - Summary of Investments-Other Than Investments in Related Parties (Details) $ in Thousands	Dec. 31, 2024 USD ($)
Investments-Other Than Investments in Related Parties
Amortized Cost	$ 6,534,918
Fair Value	6,180,621
Amount at which shown in the Balance Sheet	6,180,621
Fixed maturities
Investments-Other Than Investments in Related Parties
Amortized Cost	5,467,238
Fair Value	5,112,697
Amount at which shown in the Balance Sheet	5,112,697
Fixed maturities \| United States Government and government agencies and authorities
Investments-Other Than Investments in Related Parties
Amortized Cost	1,704,937
Fair Value	1,566,307
Amount at which shown in the Balance Sheet	1,566,307
Fixed maturities \| States, municipalities and political subdivisions
Investments-Other Than Investments in Related Parties
Amortized Cost	631,015
Fair Value	583,501
Amount at which shown in the Balance Sheet	583,501
Fixed maturities \| Residential and commercial mortgage securities
Investments-Other Than Investments in Related Parties
Amortized Cost	519,613
Fair Value	478,086
Amount at which shown in the Balance Sheet	478,086
Fixed maturities \| Asset-backed securities
Investments-Other Than Investments in Related Parties
Amortized Cost	642,395
Fair Value	631,959
Amount at which shown in the Balance Sheet	631,959
Fixed maturities \| Foreign government and agency securities
Investments-Other Than Investments in Related Parties
Amortized Cost	81,631
Fair Value	69,798
Amount at which shown in the Balance Sheet	69,798
Fixed maturities \| All other corporate bonds
Investments-Other Than Investments in Related Parties
Amortized Cost	1,887,647
Fair Value	1,783,046
Amount at which shown in the Balance Sheet	1,783,046
Short-term investments
Investments-Other Than Investments in Related Parties
Amortized Cost	763,780
Fair Value	764,024
Amount at which shown in the Balance Sheet	764,024
Other invested assets
Investments-Other Than Investments in Related Parties
Amortized Cost	303,900
Fair Value	303,900
Amount at which shown in the Balance Sheet	$ 303,900

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.

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

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Amount of investment held by insurance company, excluding investment in related party.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 320
-Name Accounting Standards Codification
-Section S99
-Paragraph 7
-Subparagraph (SX 210.12-15(Column D))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147477271/946-320-S99-7

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Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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-SubTopic 320
-Name Accounting Standards Codification
-Section S99
-Paragraph 7
-Subparagraph (SX 210.12-15(Column B))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147477271/946-320-S99-7

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Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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-SubTopic 320
-Name Accounting Standards Codification
-Section S99
-Paragraph 7
-Subparagraph (SX 210.12-15(Column C))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147477271/946-320-S99-7

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