Quarterly report [Sections 13 or 15(d)]

Securities - Summary of Debt Securities Available for Sale in an Unrealized Loss Position for Which an Allowance for Credit Losses Has Not Been Recorded (Detail)

v3.26.1
Securities - Summary of Debt Securities Available for Sale in an Unrealized Loss Position for Which an Allowance for Credit Losses Has Not Been Recorded (Detail)
$ in Thousands
Mar. 31, 2026
USD ($)
Security
Dec. 31, 2025
USD ($)
Security
Summary of Investment Holdings [Line Items]    
Available-for-Sale Within One Year, Gross Unrealized Loss $ (475) $ (46)
Available-for-Sale Within One Year, Estimated Fair Value $ 78,860 $ 9,628
Available-for-Sale Within One Year, Number of Securities | Security 24 3
Available-for-Sale More than One Year, Gross Unrealized Loss $ (65,616) $ (64,198)
Available-for-Sale More than One Year, Estimated Fair Value $ 531,570 $ 571,822
Available-for-Sale More than One Year, Number of Securities | Security 182 189
Available-for-Sale, Gross Unrealized Loss $ (66,091) $ (64,244)
Available-for-Sale, Estimated Fair Value $ 610,429 $ 581,450
Available-for-Sale, Number of Securities | Security 206 192
U.S. Treasury securities    
Summary of Investment Holdings [Line Items]    
Available-for-Sale Within One Year, Gross Unrealized Loss $ (108)  
Available-for-Sale Within One Year, Estimated Fair Value $ 43,060 $ 4,999
Available-for-Sale Within One Year, Number of Securities | Security 13 1
Available-for-Sale More than One Year, Gross Unrealized Loss $ (116) $ (157)
Available-for-Sale More than One Year, Estimated Fair Value $ 10,389 $ 10,351
Available-for-Sale More than One Year, Number of Securities | Security 3 3
Available-for-Sale, Gross Unrealized Loss $ (224) $ (157)
Available-for-Sale, Estimated Fair Value $ 53,449 $ 15,350
Available-for-Sale, Number of Securities | Security 16 4
Mortgage-backed securities - residential    
Summary of Investment Holdings [Line Items]    
Available-for-Sale Within One Year, Gross Unrealized Loss $ (246) $ (46)
Available-for-Sale Within One Year, Estimated Fair Value $ 17,161 $ 4,629
Available-for-Sale Within One Year, Number of Securities | Security 5 2
Available-for-Sale More than One Year, Gross Unrealized Loss $ (38,919) $ (38,695)
Available-for-Sale More than One Year, Estimated Fair Value $ 309,753 $ 322,912
Available-for-Sale More than One Year, Number of Securities | Security 114 114
Available-for-Sale, Gross Unrealized Loss $ (39,165) $ (38,741)
Available-for-Sale, Estimated Fair Value $ 326,914 $ 327,541
Available-for-Sale, Number of Securities | Security 119 116
Mortgage-backed securities - commercial    
Summary of Investment Holdings [Line Items]    
Available-for-Sale Within One Year, Gross Unrealized Loss $ (88)  
Available-for-Sale Within One Year, Estimated Fair Value $ 4,697  
Available-for-Sale Within One Year, Number of Securities | Security 2  
Available-for-Sale More than One Year, Gross Unrealized Loss $ (11,378) $ (11,295)
Available-for-Sale More than One Year, Estimated Fair Value $ 48,831 $ 54,316
Available-for-Sale More than One Year, Number of Securities | Security 15 16
Available-for-Sale, Gross Unrealized Loss $ (11,466) $ (11,295)
Available-for-Sale, Estimated Fair Value $ 53,528 $ 54,316
Available-for-Sale, Number of Securities | Security 17 16
Collateralized mortgage obligations    
Summary of Investment Holdings [Line Items]    
Available-for-Sale Within One Year, Gross Unrealized Loss $ (33)  
Available-for-Sale Within One Year, Estimated Fair Value $ 13,942  
Available-for-Sale Within One Year, Number of Securities | Security 4  
Available-for-Sale More than One Year, Gross Unrealized Loss $ (6,084) $ (5,933)
Available-for-Sale More than One Year, Estimated Fair Value $ 43,879 $ 50,264
Available-for-Sale More than One Year, Number of Securities | Security 21 24
Available-for-Sale, Gross Unrealized Loss $ (6,117) $ (5,933)
Available-for-Sale, Estimated Fair Value $ 57,821 $ 50,264
Available-for-Sale, Number of Securities | Security 25 24
Debt securities    
Summary of Investment Holdings [Line Items]    
Available-for-Sale More than One Year, Gross Unrealized Loss $ (779) $ (1,105)
Available-for-Sale More than One Year, Estimated Fair Value $ 52,284 $ 65,954
Available-for-Sale More than One Year, Number of Securities | Security 10 13
Available-for-Sale, Gross Unrealized Loss $ (779) $ (1,105)
Available-for-Sale, Estimated Fair Value $ 52,283 $ 65,954
Available-for-Sale, Number of Securities | Security 10 13
Total U.S. government agency and sponsored agency obligations    
Summary of Investment Holdings [Line Items]    
Available-for-Sale Within One Year, Gross Unrealized Loss $ (367) $ (46)
Available-for-Sale Within One Year, Estimated Fair Value $ 35,800 $ 4,629
Available-for-Sale Within One Year, Number of Securities | Security 11 2
Available-for-Sale More than One Year, Gross Unrealized Loss $ (57,160) $ (57,028)
Available-for-Sale More than One Year, Estimated Fair Value $ 454,747 $ 493,446
Available-for-Sale More than One Year, Number of Securities | Security 160 167
Available-for-Sale, Gross Unrealized Loss $ (57,527) $ (57,074)
Available-for-Sale, Estimated Fair Value $ 490,546 $ 498,075
Available-for-Sale, Number of Securities | Security 171 169
Municipal bonds-tax exempt    
Summary of Investment Holdings [Line Items]    
Available-for-Sale More than One Year, Gross Unrealized Loss $ (8,340) $ (7,013)
Available-for-Sale More than One Year, Estimated Fair Value $ 66,434 $ 68,025
Available-for-Sale More than One Year, Number of Securities | Security 19 19
Available-for-Sale, Gross Unrealized Loss $ (8,340) $ (7,013)
Available-for-Sale, Estimated Fair Value $ 66,434 $ 68,025
Available-for-Sale, Number of Securities | Security 19 19