Quarterly report pursuant to Section 13 or 15(d)

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

v3.19.3
Securities - Available for Sale Securities, Continuous Unrealized Loss Position, Fair value (Detail)
$ in Thousands
Sep. 30, 2019
USD ($)
Security
Dec. 31, 2018
USD ($)
Security
Summary of Investment Holdings [Line Items]    
Available-for-Sale Within One Year, Gross Unrealized Loss $ (126) $ (321)
Available-for-Sale Within One Year, Estimated Fair Value $ 52,599 $ 78,252
Available-for-Sale Within One Year, Number of Securities | Security 23 20
Available-for-Sale More than One Year, Gross Unrealized Loss $ (603) $ (8,616)
Available-for-Sale More than One Year, Estimated Fair Value $ 67,287 $ 410,128
Available-for-Sale More than One Year, Number of Securities | Security 52 188
Available-for-Sale, Gross Unrealized Loss $ (729) $ (8,937)
Available-for-Sale, Estimated Fair Value $ 119,886 $ 488,380
Available-for-Sale, Number of Securities | Security 75 208
Mortgage-backed securities    
Summary of Investment Holdings [Line Items]    
Available-for-Sale Within One Year, Gross Unrealized Loss $ (65) $ (226)
Available-for-Sale Within One Year, Estimated Fair Value $ 34,927 $ 41,527
Available-for-Sale Within One Year, Number of Securities | Security 17 10
Available-for-Sale More than One Year, Gross Unrealized Loss $ (171) $ (5,758)
Available-for-Sale More than One Year, Estimated Fair Value $ 19,712 $ 244,550
Available-for-Sale More than One Year, Number of Securities | Security 14 106
Available-for-Sale, Gross Unrealized Loss $ (236) $ (5,984)
Available-for-Sale, Estimated Fair Value $ 54,639 $ 286,077
Available-for-Sale, Number of Securities | Security 31 116
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 More than One Year, Gross Unrealized Loss   $ 0
Available-for-Sale More than One Year, Estimated Fair Value   $ 0
Available-for-Sale More than One Year, Number of Securities | Security   0
Available-for-Sale, Gross Unrealized Loss   $ (7)
Available-for-Sale, Estimated Fair Value   $ 14,797
Available-for-Sale, Number of Securities | Security   2
Collateralized mortgage obligations    
Summary of Investment Holdings [Line Items]    
Available-for-Sale Within One Year, Gross Unrealized Loss $ (60) $ (59)
Available-for-Sale Within One Year, Estimated Fair Value $ 16,173 $ 13,732
Available-for-Sale Within One Year, Number of Securities | Security 5 3
Available-for-Sale More than One Year, Gross Unrealized Loss $ (424) $ (2,273)
Available-for-Sale More than One Year, Estimated Fair Value $ 44,584 $ 92,532
Available-for-Sale More than One Year, Number of Securities | Security 37 49
Available-for-Sale, Gross Unrealized Loss $ (484) $ (2,332)
Available-for-Sale, Estimated Fair Value $ 60,757 $ 106,264
Available-for-Sale, Number of Securities | Security 42 52
Debt securities    
Summary of Investment Holdings [Line Items]    
Available-for-Sale Within One Year, Gross Unrealized Loss $ (1) $ 0
Available-for-Sale Within One Year, Estimated Fair Value $ 1,499 $ 0
Available-for-Sale Within One Year, Number of Securities | Security 1 0
Available-for-Sale More than One Year, Gross Unrealized Loss $ (8) $ (97)
Available-for-Sale More than One Year, Estimated Fair Value $ 2,991 $ 7,402
Available-for-Sale More than One Year, Number of Securities | Security 1 3
Available-for-Sale, Gross Unrealized Loss $ (9) $ (97)
Available-for-Sale, Estimated Fair Value $ 4,490 $ 7,402
Available-for-Sale, Number of Securities | Security 2 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 $ (126) $ (285)
Available-for-Sale Within One Year, Estimated Fair Value $ 52,599 $ 55,259
Available-for-Sale Within One Year, Number of Securities | Security 23 13
Available-for-Sale More than One Year, Gross Unrealized Loss $ (603) $ (8,128)
Available-for-Sale More than One Year, Estimated Fair Value $ 67,287 $ 344,484
Available-for-Sale More than One Year, Number of Securities | Security 52 158
Available-for-Sale, Gross Unrealized Loss $ (729) $ (8,413)
Available-for-Sale, Estimated Fair Value $ 119,886 $ 399,743
Available-for-Sale, Number of Securities | Security 75 171
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