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)

v3.23.3
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, 2023
USD ($)
Security
Dec. 31, 2022
USD ($)
Security
Summary of Investment Holdings [Line Items]    
Available-for-Sale Within One Year, Gross Unrealized Loss $ (1,208) $ (4,324)
Available-for-Sale Within One Year, Estimated Fair Value $ 94,381 $ 129,210
Available-for-Sale Within One Year, Number of Securities | Security 33 49
Available-for-Sale More than One Year, Gross Unrealized Loss $ (138,823) $ (120,697)
Available-for-Sale More than One Year, Estimated Fair Value $ 722,861 $ 719,787
Available-for-Sale More than One Year, Number of Securities | Security 211 184
Available-for-Sale, Gross Unrealized Loss $ (140,030) $ (125,021)
Available-for-Sale, Estimated Fair Value $ 817,242 $ 848,997
Available-for-Sale, Number of Securities | Security 244 233
U.S. Treasury securities    
Summary of Investment Holdings [Line Items]    
Available-for-Sale Within One Year, Gross Unrealized Loss $ (212) $ (414)
Available-for-Sale Within One Year, Estimated Fair Value $ 42,415 $ 33,812
Available-for-Sale Within One Year, Number of Securities | Security 15 14
Available-for-Sale More than One Year, Gross Unrealized Loss $ (1,427) $ (1,250)
Available-for-Sale More than One Year, Estimated Fair Value $ 28,507 $ 14,215
Available-for-Sale More than One Year, Number of Securities | Security 10 4
Available-for-Sale, Gross Unrealized Loss $ (1,639) $ (1,664)
Available-for-Sale, Estimated Fair Value $ 70,922 $ 48,027
Available-for-Sale, Number of Securities | Security 25 18
Mortgage-backed securities - residential    
Summary of Investment Holdings [Line Items]    
Available-for-Sale Within One Year, Gross Unrealized Loss $ (533) $ (1,712)
Available-for-Sale Within One Year, Estimated Fair Value $ 19,097 $ 36,009
Available-for-Sale Within One Year, Number of Securities | Security 9 18
Available-for-Sale More than One Year, Gross Unrealized Loss $ (84,663) $ (73,789)
Available-for-Sale More than One Year, Estimated Fair Value $ 403,629 $ 424,302
Available-for-Sale More than One Year, Number of Securities | Security 118 105
Available-for-Sale, Gross Unrealized Loss $ (85,196) $ (75,501)
Available-for-Sale, Estimated Fair Value $ 422,726 $ 460,311
Available-for-Sale, Number of Securities | Security 127 123
Mortgage-backed securities - commercial    
Summary of Investment Holdings [Line Items]    
Available-for-Sale Within One Year, Gross Unrealized Loss   $ (84)
Available-for-Sale Within One Year, Estimated Fair Value   $ 4,069
Available-for-Sale Within One Year, Number of Securities | Security   1
Available-for-Sale More than One Year, Gross Unrealized Loss $ (14,441) $ (10,423)
Available-for-Sale More than One Year, Estimated Fair Value $ 45,966 $ 47,221
Available-for-Sale More than One Year, Number of Securities | Security 15 14
Available-for-Sale, Gross Unrealized Loss $ (14,441) $ (10,507)
Available-for-Sale, Estimated Fair Value $ 45,966 $ 51,290
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 $ (405) $ (1,011)
Available-for-Sale Within One Year, Estimated Fair Value $ 22,488 $ 23,606
Available-for-Sale Within One Year, Number of Securities | Security 6 8
Available-for-Sale More than One Year, Gross Unrealized Loss $ (11,933) $ (11,740)
Available-for-Sale More than One Year, Estimated Fair Value $ 63,770 $ 61,879
Available-for-Sale More than One Year, Number of Securities | Security 24 20
Available-for-Sale, Gross Unrealized Loss $ (12,337) $ (12,751)
Available-for-Sale, Estimated Fair Value $ 86,258 $ 85,485
Available-for-Sale, Number of Securities | Security 30 28
Debt securities    
Summary of Investment Holdings [Line Items]    
Available-for-Sale Within One Year, Gross Unrealized Loss $ (58) $ (1,103)
Available-for-Sale Within One Year, Estimated Fair Value $ 10,381 $ 31,714
Available-for-Sale Within One Year, Number of Securities | Security 3 8
Available-for-Sale More than One Year, Gross Unrealized Loss $ (10,432) $ (10,736)
Available-for-Sale More than One Year, Estimated Fair Value $ 119,538 $ 106,785
Available-for-Sale More than One Year, Number of Securities | Security 25 22
Available-for-Sale, Gross Unrealized Loss $ (10,490) $ (11,839)
Available-for-Sale, Estimated Fair Value $ 129,919 $ 138,499
Available-for-Sale, Number of Securities | Security 28 30
Total U.S. government agency and sponsored agency obligations    
Summary of Investment Holdings [Line Items]    
Available-for-Sale Within One Year, Gross Unrealized Loss $ (996) $ (3,910)
Available-for-Sale Within One Year, Estimated Fair Value $ 51,966 $ 95,398
Available-for-Sale Within One Year, Number of Securities | Security 18 35
Available-for-Sale More than One Year, Gross Unrealized Loss $ (121,469) $ (106,688)
Available-for-Sale More than One Year, Estimated Fair Value $ 632,903 $ 640,187
Available-for-Sale More than One Year, Number of Securities | Security 182 161
Available-for-Sale, Gross Unrealized Loss $ (122,464) $ (110,598)
Available-for-Sale, Estimated Fair Value $ 684,869 $ 735,585
Available-for-Sale, Number of Securities | Security 200 196
Municipal bonds-tax exempt    
Summary of Investment Holdings [Line Items]    
Available-for-Sale More than One Year, Gross Unrealized Loss $ (15,927) $ (12,759)
Available-for-Sale More than One Year, Estimated Fair Value $ 61,451 $ 65,385
Available-for-Sale More than One Year, Number of Securities | Security 19 19
Available-for-Sale, Gross Unrealized Loss $ (15,927) $ (12,759)
Available-for-Sale, Estimated Fair Value $ 61,451 $ 65,385
Available-for-Sale, Number of Securities | Security 19 19