Schedule I-Summary Of Investments-Other than Investments in Related Parties (Details) $ in Thousands	Dec. 31, 2023 USD ($)
SCHEDULE I - SUMMARY OF INVESTMENTS-OTHER THAN INVESTMENTS IN RELATED PARTIES
Cost	$ 3,635,769
Fair Value	3,676,318
Amount at which shown in the balance sheet	3,676,318
Fixed Maturities
SCHEDULE I - SUMMARY OF INVESTMENTS-OTHER THAN INVESTMENTS IN RELATED PARTIES
Cost	3,054,391
Fair Value	2,855,849
Amount at which shown in the balance sheet	2,855,849
Available-for-Sale
SCHEDULE I - SUMMARY OF INVESTMENTS-OTHER THAN INVESTMENTS IN RELATED PARTIES
Cost	3,054,391
Fair Value	2,855,849
Amount at which shown in the balance sheet	2,855,849
Equity Securities
SCHEDULE I - SUMMARY OF INVESTMENTS-OTHER THAN INVESTMENTS IN RELATED PARTIES
Cost	354,022
Fair Value	590,041
Amount at which shown in the balance sheet	590,041
Ind Misc & All Other
SCHEDULE I - SUMMARY OF INVESTMENTS-OTHER THAN INVESTMENTS IN RELATED PARTIES
Cost	117,448
Fair Value	196,202
Amount at which shown in the balance sheet	196,202
ETFs (Ind/misc)
SCHEDULE I - SUMMARY OF INVESTMENTS-OTHER THAN INVESTMENTS IN RELATED PARTIES
Cost	236,574
Fair Value	393,839
Amount at which shown in the balance sheet	393,839
Cash and Short-term Investments
SCHEDULE I - SUMMARY OF INVESTMENTS-OTHER THAN INVESTMENTS IN RELATED PARTIES
Cost	171,347
Fair Value	171,347
Amount at which shown in the balance sheet	171,347
Other Invested Assets
SCHEDULE I - SUMMARY OF INVESTMENTS-OTHER THAN INVESTMENTS IN RELATED PARTIES
Cost	56,009
Fair Value	59,081
Amount at which shown in the balance sheet	59,081
U.S. government | Available-for-Sale
SCHEDULE I - SUMMARY OF INVESTMENTS-OTHER THAN INVESTMENTS IN RELATED PARTIES
Cost	312,632
Fair Value	308,031
Amount at which shown in the balance sheet	308,031
U.S. Agency | Available-for-Sale
SCHEDULE I - SUMMARY OF INVESTMENTS-OTHER THAN INVESTMENTS IN RELATED PARTIES
Cost	60,763
Fair Value	59,826
Amount at which shown in the balance sheet	59,826
Non-U.S. government & agency | Available-for-Sale
SCHEDULE I - SUMMARY OF INVESTMENTS-OTHER THAN INVESTMENTS IN RELATED PARTIES
Cost	4,800
Fair Value	3,882
Amount at which shown in the balance sheet	3,882
Agency MBS | Available-for-Sale
SCHEDULE I - SUMMARY OF INVESTMENTS-OTHER THAN INVESTMENTS IN RELATED PARTIES
Cost	460,551
Fair Value	425,285
Amount at which shown in the balance sheet	425,285
ABS/CMBS/MBS | Available-for-Sale
SCHEDULE I - SUMMARY OF INVESTMENTS-OTHER THAN INVESTMENTS IN RELATED PARTIES
Cost	308,458
Fair Value	281,182
Amount at which shown in the balance sheet	281,182
Corporate Debt | Available-for-Sale
SCHEDULE I - SUMMARY OF INVESTMENTS-OTHER THAN INVESTMENTS IN RELATED PARTIES
Cost	1,273,187
Fair Value	1,225,019
Amount at which shown in the balance sheet	1,225,019
Municipal | Available-for-Sale
SCHEDULE I - SUMMARY OF INVESTMENTS-OTHER THAN INVESTMENTS IN RELATED PARTIES
Cost	634,000
Fair Value	552,624
Amount at which shown in the balance sheet	$ 552,624