Quarterly report pursuant to Section 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)

v3.24.3
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, 2024
USD ($)
Security
Dec. 31, 2023
USD ($)
Security
Summary of Investment Holdings [Line Items]    
Available-for-Sale Within One Year, Gross Unrealized Loss $ (166) $ (106)
Available-for-Sale Within One Year, Estimated Fair Value $ 25,716 $ 30,422
Available-for-Sale Within One Year, Number of Securities | Security 7 14
Available-for-Sale More than One Year, Gross Unrealized Loss $ (81,001) $ (102,077)
Available-for-Sale More than One Year, Estimated Fair Value $ 681,443 $ 747,988
Available-for-Sale More than One Year, Number of Securities | Security 200 213
Available-for-Sale, Gross Unrealized Loss $ (81,167) $ (102,183)
Available-for-Sale, Estimated Fair Value $ 707,159 $ 778,410
Available-for-Sale, Number of Securities | Security 207 227
U.S. Treasury securities    
Summary of Investment Holdings [Line Items]    
Available-for-Sale Within One Year, Gross Unrealized Loss $ (4) $ (57)
Available-for-Sale Within One Year, Estimated Fair Value $ 2,036 $ 21,024
Available-for-Sale Within One Year, Number of Securities | Security 1 7
Available-for-Sale More than One Year, Gross Unrealized Loss $ (472) $ (983)
Available-for-Sale More than One Year, Estimated Fair Value $ 20,756 $ 32,449
Available-for-Sale More than One Year, Number of Securities | Security 6 11
Available-for-Sale, Gross Unrealized Loss $ (476) $ (1,040)
Available-for-Sale, Estimated Fair Value $ 22,792 $ 53,473
Available-for-Sale, Number of Securities | Security 7 18
Mortgage-backed securities - residential    
Summary of Investment Holdings [Line Items]    
Available-for-Sale Within One Year, Gross Unrealized Loss   $ (11)
Available-for-Sale Within One Year, Estimated Fair Value   $ 2,324
Available-for-Sale Within One Year, Number of Securities | Security   5
Available-for-Sale More than One Year, Gross Unrealized Loss $ (48,928) $ (62,686)
Available-for-Sale More than One Year, Estimated Fair Value $ 378,056 $ 411,417
Available-for-Sale More than One Year, Number of Securities | Security 114 118
Available-for-Sale, Gross Unrealized Loss $ (48,928) $ (62,697)
Available-for-Sale, Estimated Fair Value $ 378,056 $ 413,741
Available-for-Sale, Number of Securities | Security 114 123
Mortgage-backed securities - commercial    
Summary of Investment Holdings [Line Items]    
Available-for-Sale Within One Year, Gross Unrealized Loss $ (134)  
Available-for-Sale Within One Year, Estimated Fair Value $ 11,330  
Available-for-Sale Within One Year, Number of Securities | Security 3  
Available-for-Sale More than One Year, Gross Unrealized Loss $ (10,870) $ (11,982)
Available-for-Sale More than One Year, Estimated Fair Value $ 45,238 $ 47,991
Available-for-Sale More than One Year, Number of Securities | Security 15 15
Available-for-Sale, Gross Unrealized Loss $ (11,004) $ (11,982)
Available-for-Sale, Estimated Fair Value $ 56,568 $ 47,991
Available-for-Sale, Number of Securities | Security 18 15
Collateralized mortgage obligations    
Summary of Investment Holdings [Line Items]    
Available-for-Sale Within One Year, Gross Unrealized Loss $ (28) $ (38)
Available-for-Sale Within One Year, Estimated Fair Value $ 12,350 $ 7,074
Available-for-Sale Within One Year, Number of Securities | Security 3 2
Available-for-Sale More than One Year, Gross Unrealized Loss $ (7,484) $ (9,611)
Available-for-Sale More than One Year, Estimated Fair Value $ 57,768 $ 63,610
Available-for-Sale More than One Year, Number of Securities | Security 24 24
Available-for-Sale, Gross Unrealized Loss $ (7,512) $ (9,649)
Available-for-Sale, Estimated Fair Value $ 70,118 $ 70,684
Available-for-Sale, Number of Securities | Security 27 26
Debt securities    
Summary of Investment Holdings [Line Items]    
Available-for-Sale More than One Year, Gross Unrealized Loss $ (4,135) $ (7,590)
Available-for-Sale More than One Year, Estimated Fair Value $ 112,391 $ 124,625
Available-for-Sale More than One Year, Number of Securities | Security 22 26
Available-for-Sale, Gross Unrealized Loss $ (4,135) $ (7,590)
Available-for-Sale, Estimated Fair Value $ 112,391 $ 124,625
Available-for-Sale, Number of Securities | Security 22 26
Total U.S. government agency and sponsored agency obligations    
Summary of Investment Holdings [Line Items]    
Available-for-Sale Within One Year, Gross Unrealized Loss $ (162) $ (49)
Available-for-Sale Within One Year, Estimated Fair Value $ 23,680 $ 9,398
Available-for-Sale Within One Year, Number of Securities | Security 6 7
Available-for-Sale More than One Year, Gross Unrealized Loss $ (71,417) $ (91,869)
Available-for-Sale More than One Year, Estimated Fair Value $ 593,453 $ 647,643
Available-for-Sale More than One Year, Number of Securities | Security 175 183
Available-for-Sale, Gross Unrealized Loss $ (71,579) $ (91,918)
Available-for-Sale, Estimated Fair Value $ 617,133 $ 657,041
Available-for-Sale, Number of Securities | Security 181 190
Municipal bonds-tax exempt    
Summary of Investment Holdings [Line Items]    
Available-for-Sale More than One Year, Gross Unrealized Loss $ (9,112) $ (9,225)
Available-for-Sale More than One Year, Estimated Fair Value $ 67,234 $ 67,896
Available-for-Sale More than One Year, Number of Securities | Security 19 19
Available-for-Sale, Gross Unrealized Loss $ (9,112) $ (9,225)
Available-for-Sale, Estimated Fair Value $ 67,234 $ 67,896
Available-for-Sale, Number of Securities | Security 19 19