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)

v3.25.3
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, 2025
USD ($)
Security
Dec. 31, 2024
USD ($)
Security
Summary of Investment Holdings [Line Items]    
Available-for-Sale Within One Year, Gross Unrealized Loss $ (39) $ (1,447)
Available-for-Sale Within One Year, Estimated Fair Value $ 18,983 $ 144,646
Available-for-Sale Within One Year, Number of Securities | Security 6 42
Available-for-Sale More than One Year, Gross Unrealized Loss $ (70,566) $ (98,219)
Available-for-Sale More than One Year, Estimated Fair Value $ 584,173 $ 630,005
Available-for-Sale More than One Year, Number of Securities | Security 189 195
Available-for-Sale, Gross Unrealized Loss $ (70,605) $ (99,666)
Available-for-Sale, Estimated Fair Value $ 603,156 $ 774,651
Available-for-Sale, Number of Securities | Security 195 237
U.S. Treasury securities    
Summary of Investment Holdings [Line Items]    
Available-for-Sale Within One Year, Gross Unrealized Loss $ (8) $ (61)
Available-for-Sale Within One Year, Estimated Fair Value $ 10,024 $ 13,603
Available-for-Sale Within One Year, Number of Securities | Security 3 6
Available-for-Sale More than One Year, Gross Unrealized Loss $ (226) $ (460)
Available-for-Sale More than One Year, Estimated Fair Value $ 10,285 $ 9,771
Available-for-Sale More than One Year, Number of Securities | Security 3 3
Available-for-Sale, Gross Unrealized Loss $ (234) $ (521)
Available-for-Sale, Estimated Fair Value $ 20,309 $ 23,374
Available-for-Sale, Number of Securities | Security 6 9
Mortgage-backed securities - residential    
Summary of Investment Holdings [Line Items]    
Available-for-Sale Within One Year, Gross Unrealized Loss $ (31) $ (271)
Available-for-Sale Within One Year, Estimated Fair Value $ 8,959 $ 23,276
Available-for-Sale Within One Year, Number of Securities | Security 3 10
Available-for-Sale More than One Year, Gross Unrealized Loss $ (42,577) $ (61,372)
Available-for-Sale More than One Year, Estimated Fair Value $ 332,541 $ 351,793
Available-for-Sale More than One Year, Number of Securities | Security 114 114
Available-for-Sale, Gross Unrealized Loss $ (42,608) $ (61,643)
Available-for-Sale, Estimated Fair Value $ 341,500 $ 375,069
Available-for-Sale, Number of Securities | Security 117 124
Mortgage-backed securities - commercial    
Summary of Investment Holdings [Line Items]    
Available-for-Sale Within One Year, Gross Unrealized Loss   $ (447)
Available-for-Sale Within One Year, Estimated Fair Value   $ 19,092
Available-for-Sale Within One Year, Number of Securities | Security   5
Available-for-Sale More than One Year, Gross Unrealized Loss $ (11,863) $ (12,608)
Available-for-Sale More than One Year, Estimated Fair Value $ 54,856 $ 41,817
Available-for-Sale More than One Year, Number of Securities | Security 16 14
Available-for-Sale, Gross Unrealized Loss $ (11,863) $ (13,055)
Available-for-Sale, Estimated Fair Value $ 54,856 $ 60,909
Available-for-Sale, Number of Securities | Security 16 19
Collateralized mortgage obligations    
Summary of Investment Holdings [Line Items]    
Available-for-Sale Within One Year, Gross Unrealized Loss   $ (645)
Available-for-Sale Within One Year, Estimated Fair Value   $ 76,963
Available-for-Sale Within One Year, Number of Securities | Security   18
Available-for-Sale More than One Year, Gross Unrealized Loss $ (6,446) $ (8,756)
Available-for-Sale More than One Year, Estimated Fair Value $ 53,588 $ 54,020
Available-for-Sale More than One Year, Number of Securities | Security 24 24
Available-for-Sale, Gross Unrealized Loss $ (6,446) $ (9,401)
Available-for-Sale, Estimated Fair Value $ 53,588 $ 130,983
Available-for-Sale, Number of Securities | Security 24 42
Debt securities    
Summary of Investment Holdings [Line Items]    
Available-for-Sale Within One Year, Gross Unrealized Loss   $ (23)
Available-for-Sale Within One Year, Estimated Fair Value   $ 11,712
Available-for-Sale Within One Year, Number of Securities | Security   3
Available-for-Sale More than One Year, Gross Unrealized Loss $ (1,558) $ (3,946)
Available-for-Sale More than One Year, Estimated Fair Value $ 65,498 $ 107,595
Available-for-Sale More than One Year, Number of Securities | Security 13 21
Available-for-Sale, Gross Unrealized Loss $ (1,558) $ (3,969)
Available-for-Sale, Estimated Fair Value $ 65,498 $ 119,307
Available-for-Sale, Number of Securities | Security 13 24
Total U.S. government agency and sponsored agency obligations    
Summary of Investment Holdings [Line Items]    
Available-for-Sale Within One Year, Gross Unrealized Loss $ (31) $ (1,386)
Available-for-Sale Within One Year, Estimated Fair Value $ 8,959 $ 131,043
Available-for-Sale Within One Year, Number of Securities | Security 3 36
Available-for-Sale More than One Year, Gross Unrealized Loss $ (62,444) $ (86,682)
Available-for-Sale More than One Year, Estimated Fair Value $ 506,483 $ 555,225
Available-for-Sale More than One Year, Number of Securities | Security 167 173
Available-for-Sale, Gross Unrealized Loss $ (62,475) $ (88,068)
Available-for-Sale, Estimated Fair Value $ 515,442 $ 686,268
Available-for-Sale, Number of Securities | Security 170 209
Municipal bonds-tax exempt    
Summary of Investment Holdings [Line Items]    
Available-for-Sale More than One Year, Gross Unrealized Loss $ (7,896) $ (11,077)
Available-for-Sale More than One Year, Estimated Fair Value $ 67,405 $ 65,009
Available-for-Sale More than One Year, Number of Securities | Security 19 19
Available-for-Sale, Gross Unrealized Loss $ (7,896) $ (11,077)
Available-for-Sale, Estimated Fair Value $ 67,405 $ 65,009
Available-for-Sale, Number of Securities | Security 19 19