v3.25.1
Schedule of Total Investment Return (Detail) - USD ($)
$ in Thousands
 3 Months Ended
Mar. 31, 2025
Mar. 31, 2024
Investments, Debt and Equity Securities [Abstract]    
Net investment income $ 14,782 $ 14,520
Net realized investment gains 136 847
Change in unrealized holding gains (losses) 4,383 3,547
Net realized and unrealized investment returns 4,519 4,394
Total investment return $ 19,301 $ 18,914
Total investment return % [1] 1.30% 1.30%
Average investment portfolio [2] $ 1,436,218 $ 1,403,878
[1] Not annualized.
[2] Average of total cash and invested assets, net of receivable/payable for securities, as of the beginning and end of the period.