Annual report pursuant to Section 13 and 15(d)

Securities - Available for Sale Securities, Continuous Unrealized Loss Position, Fair value (Detail)

v3.19.3.a.u2
Securities - Available for Sale Securities, Continuous Unrealized Loss Position, Fair value (Detail)
$ in Thousands
Dec. 31, 2019
USD ($)
Security
Dec. 31, 2018
USD ($)
Security
Summary of Investment Holdings [Line Items]    
Available-for-Sale Within One Year, Gross Unrealized Loss $ (318) $ (321)
Available-for-Sale Within One Year, Estimated Fair Value $ 100,916 $ 78,252
Available-for-Sale Within One Year, Number of Securities | Security 33 20
Available-for-Sale More than One Year, Gross Unrealized Loss $ (483) $ (8,616)
Available-for-Sale More than One Year, Estimated Fair Value $ 61,690 $ 410,128
Available-for-Sale More than One Year, Number of Securities | Security 51 188
Available-for-Sale, Gross Unrealized Loss $ (801) $ (8,937)
Available-for-Sale, Estimated Fair Value $ 162,606 $ 488,380
Available-for-Sale, Number of Securities | Security 84 208
Municipal bonds-tax exempt    
Summary of Investment Holdings [Line Items]    
Available-for-Sale Within One Year, Gross Unrealized Loss   $ (29)
Available-for-Sale Within One Year, Estimated Fair Value   $ 8,196
Available-for-Sale Within One Year, Number of Securities | Security   5
Available-for-Sale More than One Year, Gross Unrealized Loss   $ (488)
Available-for-Sale More than One Year, Estimated Fair Value   $ 65,644
Available-for-Sale More than One Year, Number of Securities | Security   30
Available-for-Sale, Gross Unrealized Loss   $ (517)
Available-for-Sale, Estimated Fair Value   $ 73,840
Available-for-Sale, Number of Securities | Security   35
Mortgage-backed securities    
Summary of Investment Holdings [Line Items]    
Available-for-Sale Within One Year, Gross Unrealized Loss $ (186) $ (226)
Available-for-Sale Within One Year, Estimated Fair Value $ 51,261 $ 41,527
Available-for-Sale Within One Year, Number of Securities | Security 17 10
Available-for-Sale More than One Year, Gross Unrealized Loss $ (161) $ (5,758)
Available-for-Sale More than One Year, Estimated Fair Value $ 18,757 $ 244,550
Available-for-Sale More than One Year, Number of Securities | Security 14 106
Available-for-Sale, Gross Unrealized Loss $ (347) $ (5,984)
Available-for-Sale, Estimated Fair Value $ 70,018 $ 286,077
Available-for-Sale, Number of Securities | Security 31 116
Collateralized mortgage obligations    
Summary of Investment Holdings [Line Items]    
Available-for-Sale Within One Year, Gross Unrealized Loss $ (112) $ (59)
Available-for-Sale Within One Year, Estimated Fair Value $ 41,419 $ 13,732
Available-for-Sale Within One Year, Number of Securities | Security 14 3
Available-for-Sale More than One Year, Gross Unrealized Loss $ (320) $ (2,273)
Available-for-Sale More than One Year, Estimated Fair Value $ 39,936 $ 92,532
Available-for-Sale More than One Year, Number of Securities | Security 36 49
Available-for-Sale, Gross Unrealized Loss $ (432) $ (2,332)
Available-for-Sale, Estimated Fair Value $ 81,355 $ 106,264
Available-for-Sale, Number of Securities | Security 50 52
Debt securities    
Summary of Investment Holdings [Line Items]    
Available-for-Sale Within One Year, Gross Unrealized Loss $ (20)  
Available-for-Sale Within One Year, Estimated Fair Value $ 8,235  
Available-for-Sale Within One Year, Number of Securities | Security 2  
Available-for-Sale More than One Year, Gross Unrealized Loss $ (3) $ (97)
Available-for-Sale More than One Year, Estimated Fair Value $ 2,997 $ 7,402
Available-for-Sale More than One Year, Number of Securities | Security 1 3
Available-for-Sale, Gross Unrealized Loss $ (22) $ (97)
Available-for-Sale, Estimated Fair Value $ 11,233 $ 7,402
Available-for-Sale, Number of Securities | Security 3 3
Total U.S. government agency and sponsored agency obligations    
Summary of Investment Holdings [Line Items]    
Available-for-Sale Within One Year, Gross Unrealized Loss $ (318) $ (285)
Available-for-Sale Within One Year, Estimated Fair Value $ 100,916 $ 55,259
Available-for-Sale Within One Year, Number of Securities | Security 33 13
Available-for-Sale More than One Year, Gross Unrealized Loss $ (483) $ (8,128)
Available-for-Sale More than One Year, Estimated Fair Value $ 61,690 $ 344,484
Available-for-Sale More than One Year, Number of Securities | Security 51 158
Available-for-Sale, Gross Unrealized Loss $ (801) $ (8,413)
Available-for-Sale, Estimated Fair Value $ 162,606 $ 399,743
Available-for-Sale, Number of Securities | Security 84 171
U.S. Treasury securities    
Summary of Investment Holdings [Line Items]    
Available-for-Sale Within One Year, Gross Unrealized Loss   $ (7)
Available-for-Sale Within One Year, Estimated Fair Value   $ 14,797
Available-for-Sale Within One Year, Number of Securities | Security   2
Available-for-Sale, Gross Unrealized Loss   $ (7)
Available-for-Sale, Estimated Fair Value   $ 14,797
Available-for-Sale, Number of Securities | Security   2