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)

v3.26.3
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
Sep. 30, 2026
USD ($)
Security
Dec. 31, 2025
USD ($)
Security
Summary of Investment Holdings [Line Items]    
Available-for-Sale Within One Year, Gross Unrealized Loss $ (6,622) $ (46)
Available-for-Sale Within One Year, Estimated Fair Value $ 410,964 $ 9,628
Available-for-Sale Within One Year, Number of Securities | Security 105 3
Available-for-Sale More than One Year, Gross Unrealized Loss $ (81,761) $ (64,198)
Available-for-Sale More than One Year, Estimated Fair Value $ 448,993 $ 571,822
Available-for-Sale More than One Year, Number of Securities | Security 175 189
Available-for-Sale, Gross Unrealized Loss $ (88,383) $ (64,244)
Available-for-Sale, Estimated Fair Value $ 859,957 $ 581,450
Available-for-Sale, Number of Securities | Security 280 192
U.S. Treasury securities    
Summary of Investment Holdings [Line Items]    
Available-for-Sale Within One Year, Gross Unrealized Loss $ (1,205)  
Available-for-Sale Within One Year, Estimated Fair Value $ 221,567 $ 4,999
Available-for-Sale Within One Year, Number of Securities | Security 39 1
Available-for-Sale More than One Year, Gross Unrealized Loss $ (17) $ (157)
Available-for-Sale More than One Year, Estimated Fair Value $ 3,484 $ 10,351
Available-for-Sale More than One Year, Number of Securities | Security 1 3
Available-for-Sale, Gross Unrealized Loss $ (1,222) $ (157)
Available-for-Sale, Estimated Fair Value $ 225,051 $ 15,350
Available-for-Sale, Number of Securities | Security 40 4
Mortgage-backed securities - residential    
Summary of Investment Holdings [Line Items]    
Available-for-Sale Within One Year, Gross Unrealized Loss $ (2,389) $ (46)
Available-for-Sale Within One Year, Estimated Fair Value $ 55,019 $ 4,629
Available-for-Sale Within One Year, Number of Securities | Security 20 2
Available-for-Sale More than One Year, Gross Unrealized Loss $ (48,345) $ (38,695)
Available-for-Sale More than One Year, Estimated Fair Value $ 275,194 $ 322,912
Available-for-Sale More than One Year, Number of Securities | Security 115 114
Available-for-Sale, Gross Unrealized Loss $ (50,734) $ (38,741)
Available-for-Sale, Estimated Fair Value $ 330,213 $ 327,541
Available-for-Sale, Number of Securities | Security 135 116
Mortgage-backed securities - commercial    
Summary of Investment Holdings [Line Items]    
Available-for-Sale Within One Year, Gross Unrealized Loss $ (940)  
Available-for-Sale Within One Year, Estimated Fair Value $ 18,343  
Available-for-Sale Within One Year, Number of Securities | Security 6  
Available-for-Sale More than One Year, Gross Unrealized Loss $ (13,812) $ (11,295)
Available-for-Sale More than One Year, Estimated Fair Value $ 45,471 $ 54,316
Available-for-Sale More than One Year, Number of Securities | Security 14 16
Available-for-Sale, Gross Unrealized Loss $ (14,752) $ (11,295)
Available-for-Sale, Estimated Fair Value $ 63,814 $ 54,316
Available-for-Sale, Number of Securities | Security 20 16
Collateralized mortgage obligations    
Summary of Investment Holdings [Line Items]    
Available-for-Sale Within One Year, Gross Unrealized Loss $ (1,923)  
Available-for-Sale Within One Year, Estimated Fair Value $ 106,199  
Available-for-Sale Within One Year, Number of Securities | Security 38  
Available-for-Sale More than One Year, Gross Unrealized Loss $ (6,971) $ (5,933)
Available-for-Sale More than One Year, Estimated Fair Value $ 38,652 $ 50,264
Available-for-Sale More than One Year, Number of Securities | Security 21 24
Available-for-Sale, Gross Unrealized Loss $ (8,894) $ (5,933)
Available-for-Sale, Estimated Fair Value $ 144,851 $ 50,264
Available-for-Sale, Number of Securities | Security 59 24
Other U.S. government agency obligations    
Summary of Investment Holdings [Line Items]    
Available-for-Sale Within One Year, Gross Unrealized Loss $ (165)  
Available-for-Sale Within One Year, Estimated Fair Value $ 9,836  
Available-for-Sale Within One Year, Number of Securities | Security 2  
Available-for-Sale More than One Year, Gross Unrealized Loss $ (319) $ (1,105)
Available-for-Sale More than One Year, Estimated Fair Value $ 24,247 $ 65,954
Available-for-Sale More than One Year, Number of Securities | Security 5 13
Available-for-Sale, Gross Unrealized Loss $ (484) $ (1,105)
Available-for-Sale, Estimated Fair Value $ 34,083 $ 65,954
Available-for-Sale, Number of Securities | Security 7 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 $ (5,417) $ (46)
Available-for-Sale Within One Year, Estimated Fair Value $ 189,397 $ 4,629
Available-for-Sale Within One Year, Number of Securities | Security 66 2
Available-for-Sale More than One Year, Gross Unrealized Loss $ (69,447) $ (57,028)
Available-for-Sale More than One Year, Estimated Fair Value $ 383,564 $ 493,446
Available-for-Sale More than One Year, Number of Securities | Security 155 167
Available-for-Sale, Gross Unrealized Loss $ (74,864) $ (57,074)
Available-for-Sale, Estimated Fair Value $ 572,961 $ 498,075
Available-for-Sale, Number of Securities | Security 221 169
Municipal bonds-tax exempt    
Summary of Investment Holdings [Line Items]    
Available-for-Sale More than One Year, Gross Unrealized Loss $ (12,297) $ (7,013)
Available-for-Sale More than One Year, Estimated Fair Value $ 61,945 $ 68,025
Available-for-Sale More than One Year, Number of Securities | Security 19 19
Available-for-Sale, Gross Unrealized Loss $ (12,297) $ (7,013)
Available-for-Sale, Estimated Fair Value $ 61,945 $ 68,025
Available-for-Sale, Number of Securities | Security 19 19