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)

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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, 2024
USD ($)
Security
Dec. 31, 2023
USD ($)
Security
Summary of Investment Holdings [Line Items]    
Available-for-Sale Within One Year, Gross Unrealized Loss $ (515) $ (106)
Available-for-Sale Within One Year, Estimated Fair Value $ 98,971 $ 30,422
Available-for-Sale Within One Year, Number of Securities | Security 31 14
Available-for-Sale More than One Year, Gross Unrealized Loss $ (106,229) $ (102,077)
Available-for-Sale More than One Year, Estimated Fair Value $ 729,401 $ 747,988
Available-for-Sale More than One Year, Number of Securities | Security 214 213
Available-for-Sale, Gross Unrealized Loss $ (106,744) $ (102,183)
Available-for-Sale, Estimated Fair Value $ 828,372 $ 778,410
Available-for-Sale, Number of Securities | Security 245 227
U.S. Treasury securities    
Summary of Investment Holdings [Line Items]    
Available-for-Sale Within One Year, Gross Unrealized Loss $ (159) $ (57)
Available-for-Sale Within One Year, Estimated Fair Value $ 43,837 $ 21,024
Available-for-Sale Within One Year, Number of Securities | Security 13 7
Available-for-Sale More than One Year, Gross Unrealized Loss $ (965) $ (983)
Available-for-Sale More than One Year, Estimated Fair Value $ 31,489 $ 32,449
Available-for-Sale More than One Year, Number of Securities | Security 11 11
Available-for-Sale, Gross Unrealized Loss $ (1,124) $ (1,040)
Available-for-Sale, Estimated Fair Value $ 75,326 $ 53,473
Available-for-Sale, Number of Securities | Security 24 18
Mortgage-backed securities - residential    
Summary of Investment Holdings [Line Items]    
Available-for-Sale Within One Year, Gross Unrealized Loss $ (88) $ (11)
Available-for-Sale Within One Year, Estimated Fair Value $ 16,344 $ 2,324
Available-for-Sale Within One Year, Number of Securities | Security 8 5
Available-for-Sale More than One Year, Gross Unrealized Loss $ (65,179) $ (62,686)
Available-for-Sale More than One Year, Estimated Fair Value $ 395,536 $ 411,417
Available-for-Sale More than One Year, Number of Securities | Security 118 118
Available-for-Sale, Gross Unrealized Loss $ (65,267) $ (62,697)
Available-for-Sale, Estimated Fair Value $ 411,880 $ 413,741
Available-for-Sale, Number of Securities | Security 126 123
Mortgage-backed securities - commercial    
Summary of Investment Holdings [Line Items]    
Available-for-Sale More than One Year, Gross Unrealized Loss $ (12,383) $ (11,982)
Available-for-Sale More than One Year, Estimated Fair Value $ 47,220 $ 47,991
Available-for-Sale More than One Year, Number of Securities | Security 15 15
Available-for-Sale, Gross Unrealized Loss $ (12,383) $ (11,982)
Available-for-Sale, Estimated Fair Value $ 47,220 $ 47,991
Available-for-Sale, Number of Securities | Security 15 15
Collateralized mortgage obligations    
Summary of Investment Holdings [Line Items]    
Available-for-Sale Within One Year, Gross Unrealized Loss $ (268) $ (38)
Available-for-Sale Within One Year, Estimated Fair Value $ 38,790 $ 7,074
Available-for-Sale Within One Year, Number of Securities | Security 10 2
Available-for-Sale More than One Year, Gross Unrealized Loss $ (9,860) $ (9,611)
Available-for-Sale More than One Year, Estimated Fair Value $ 63,898 $ 63,610
Available-for-Sale More than One Year, Number of Securities | Security 25 24
Available-for-Sale, Gross Unrealized Loss $ (10,128) $ (9,649)
Available-for-Sale, Estimated Fair Value $ 102,688 $ 70,684
Available-for-Sale, Number of Securities | Security 35 26
Debt securities    
Summary of Investment Holdings [Line Items]    
Available-for-Sale More than One Year, Gross Unrealized Loss $ (7,420) $ (7,590)
Available-for-Sale More than One Year, Estimated Fair Value $ 124,816 $ 124,625
Available-for-Sale More than One Year, Number of Securities | Security 26 26
Available-for-Sale, Gross Unrealized Loss $ (7,420) $ (7,590)
Available-for-Sale, Estimated Fair Value $ 124,816 $ 124,625
Available-for-Sale, Number of Securities | Security 26 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 $ (356) $ (49)
Available-for-Sale Within One Year, Estimated Fair Value $ 55,134 $ 9,398
Available-for-Sale Within One Year, Number of Securities | Security 18 7
Available-for-Sale More than One Year, Gross Unrealized Loss $ (94,842) $ (91,869)
Available-for-Sale More than One Year, Estimated Fair Value $ 631,470 $ 647,643
Available-for-Sale More than One Year, Number of Securities | Security 184 183
Available-for-Sale, Gross Unrealized Loss $ (95,198) $ (91,918)
Available-for-Sale, Estimated Fair Value $ 686,604 $ 657,041
Available-for-Sale, Number of Securities | Security 202 190
Municipal bonds-tax exempt    
Summary of Investment Holdings [Line Items]    
Available-for-Sale More than One Year, Gross Unrealized Loss $ (10,422) $ (9,225)
Available-for-Sale More than One Year, Estimated Fair Value $ 66,442 $ 67,896
Available-for-Sale More than One Year, Number of Securities | Security 19 19
Available-for-Sale, Gross Unrealized Loss $ (10,422) $ (9,225)
Available-for-Sale, Estimated Fair Value $ 66,442 $ 67,896
Available-for-Sale, Number of Securities | Security 19 19