v3.26.3
Securities - Gross Unrealized Losses, Aggregated by Investment Category and Length of Time (Detail) - USD ($)
$ in Thousands
Sep. 30, 2026
Dec. 31, 2025
Schedule of Available-for-sale Securities [Line Items]    
Gross Unrealized Losses, Less Than Twelve Months $ (6,713) $ (61)
Fair Value, Less Than Twelve Months 237,182 17,786
Gross Unrealized Losses, Twelve Months and Over (16,879) (16,365)
Fair Value, Twelve Months and Over 216,694 274,852
Gross Unrealized Losses, Total (23,592) (16,426)
Fair Value, Total 453,876 292,638
U.S. Treasury [Member]    
Schedule of Available-for-sale Securities [Line Items]    
Gross Unrealized Losses, Less Than Twelve Months (2,282) (5)
Fair Value, Less Than Twelve Months 92,346 7,038
Gross Unrealized Losses, Twelve Months and Over (2,124) (2,287)
Fair Value, Twelve Months and Over 43,171 50,161
Gross Unrealized Losses, Total (4,406) (2,292)
Fair Value, Total 135,517 57,199
U.S. Government Agencies [Member]    
Schedule of Available-for-sale Securities [Line Items]    
Gross Unrealized Losses, Less Than Twelve Months (156) 0
Fair Value, Less Than Twelve Months 8,964 0
Gross Unrealized Losses, Twelve Months and Over (3,231) (4,181)
Fair Value, Twelve Months and Over 82,974 120,103
Gross Unrealized Losses, Total (3,387) (4,181)
Fair Value, Total 91,938 120,103
Mortgage-backed Securities [Member]    
Schedule of Available-for-sale Securities [Line Items]    
Gross Unrealized Losses, Less Than Twelve Months (4,056) (50)
Fair Value, Less Than Twelve Months 127,049 8,214
Gross Unrealized Losses, Twelve Months and Over (8,655) (7,683)
Fair Value, Twelve Months and Over 46,951 59,386
Gross Unrealized Losses, Total (12,711) (7,733)
Fair Value, Total 174,000 67,600
State and Local Governments [Member]    
Schedule of Available-for-sale Securities [Line Items]    
Gross Unrealized Losses, Less Than Twelve Months (219) (6)
Fair Value, Less Than Twelve Months 8,823 2,534
Gross Unrealized Losses, Twelve Months and Over (2,869) (2,214)
Fair Value, Twelve Months and Over 43,598 45,202
Gross Unrealized Losses, Total (3,088) (2,220)
Fair Value, Total $ 52,421 $ 47,736