v3.26.1
Summary of Securities with Gross Unrealized Losses (Detail) - Fixed Income Securities - USD ($)
$ in Thousands
Mar. 31, 2026
Dec. 31, 2025
Schedule Of Available For Sale Securities [Line Items]    
Less than 12 months, Fair Value $ 539,652 $ 79,220
Less than 12 months, Gross Unrealized Losses (3,024) (2,728)
12 months or longer, Fair Value 163,577 182,408
12 months or longer, Gross Unrealized Losses (8,036) (7,737)
Total, Fair Value 703,229 261,628
Total, Gross Unrealized Losses (11,060) (10,465)
U.S. Treasuries    
Schedule Of Available For Sale Securities [Line Items]    
Less than 12 months, Fair Value 398,716 21,804
Less than 12 months, Gross Unrealized Losses (56) (1)
12 months or longer, Fair Value 7,652 7,643
12 months or longer, Gross Unrealized Losses (109) (119)
Total, Fair Value 406,368 29,447
Total, Gross Unrealized Losses (165) (120)
Obligations of States and Political Subdivisions    
Schedule Of Available For Sale Securities [Line Items]    
Less than 12 months, Fair Value 1,450 0
Less than 12 months, Gross Unrealized Losses 0 0
12 months or longer, Fair Value 12,660 12,714
12 months or longer, Gross Unrealized Losses (384) (350)
Total, Fair Value 14,110 12,714
Total, Gross Unrealized Losses (384) (350)
Mortgage Backed Securities    
Schedule Of Available For Sale Securities [Line Items]    
Less than 12 months, Fair Value 43,065 15,293
Less than 12 months, Gross Unrealized Losses (771) (716)
12 months or longer, Fair Value 23,099 24,918
12 months or longer, Gross Unrealized Losses (2,739) (2,735)
Total, Fair Value 66,164 40,211
Total, Gross Unrealized Losses (3,510) (3,451)
Asset-backed Securities    
Schedule Of Available For Sale Securities [Line Items]    
Less than 12 months, Fair Value 49,616 24,080
Less than 12 months, Gross Unrealized Losses (1,982) (1,872)
12 months or longer, Fair Value 30,351 31,604
12 months or longer, Gross Unrealized Losses (1,846) (1,777)
Total, Fair Value 79,967 55,684
Total, Gross Unrealized Losses (3,828) (3,649)
Commercial Mortgage-Backed Securities    
Schedule Of Available For Sale Securities [Line Items]    
Less than 12 months, Fair Value 10,838 13,954
Less than 12 months, Gross Unrealized Losses (65) (96)
12 months or longer, Fair Value 31,862 32,183
12 months or longer, Gross Unrealized Losses (1,392) (1,367)
Total, Fair Value 42,700 46,137
Total, Gross Unrealized Losses (1,457) (1,463)
Corporate Bonds    
Schedule Of Available For Sale Securities [Line Items]    
Less than 12 months, Fair Value 31,341 2,509
Less than 12 months, Gross Unrealized Losses (107) (26)
12 months or longer, Fair Value 38,166 48,935
12 months or longer, Gross Unrealized Losses (873) (841)
Total, Fair Value 69,507 51,444
Total, Gross Unrealized Losses (980) (867)
Foreign Corporate Bonds    
Schedule Of Available For Sale Securities [Line Items]    
Less than 12 months, Fair Value 4,626 1,580
Less than 12 months, Gross Unrealized Losses (43) (17)
12 months or longer, Fair Value 19,787 24,411
12 months or longer, Gross Unrealized Losses (693) (548)
Total, Fair Value 24,413 25,991
Total, Gross Unrealized Losses $ (736) $ (565)