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
Jun. 30, 2019
USD ($)
Security
Dec. 31, 2018
USD ($)
Security
Summary of Investment Holdings [Line Items]    
Available-for-Sale Within One Year, Gross Unrealized Loss $ (22) $ (321)
Available-for-Sale Within One Year, Estimated Fair Value $ 21,255 $ 78,252
Available-for-Sale Within One Year, Number of Securities | Security 5 20
Available-for-Sale More than One Year, Gross Unrealized Loss $ (1,262) $ (8,616)
Available-for-Sale More than One Year, Estimated Fair Value $ 191,319 $ 410,128
Available-for-Sale More than One Year, Number of Securities | Security 104 188
Available-for-Sale, Gross Unrealized Loss $ (1,284) $ (8,937)
Available-for-Sale, Estimated Fair Value $ 212,574 $ 488,380
Available-for-Sale, Number of Securities | Security 109 208
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
Mortgage-backed securities    
Summary of Investment Holdings [Line Items]    
Available-for-Sale Within One Year, Gross Unrealized Loss $ (4) $ (226)
Available-for-Sale Within One Year, Estimated Fair Value $ 14,114 $ 41,527
Available-for-Sale Within One Year, Number of Securities | Security 3 10
Available-for-Sale More than One Year, Gross Unrealized Loss $ (681) $ (5,758)
Available-for-Sale More than One Year, Estimated Fair Value $ 124,833 $ 244,550
Available-for-Sale More than One Year, Number of Securities | Security 61 106
Available-for-Sale, Gross Unrealized Loss $ (685) $ (5,984)
Available-for-Sale, Estimated Fair Value $ 138,947 $ 286,077
Available-for-Sale, Number of Securities | Security 64 116
Collateralized mortgage obligations    
Summary of Investment Holdings [Line Items]    
Available-for-Sale Within One Year, Gross Unrealized Loss $ (18) $ (59)
Available-for-Sale Within One Year, Estimated Fair Value $ 7,141 $ 13,732
Available-for-Sale Within One Year, Number of Securities | Security 2 3
Available-for-Sale More than One Year, Gross Unrealized Loss $ (562) $ (2,273)
Available-for-Sale More than One Year, Estimated Fair Value $ 62,006 $ 92,532
Available-for-Sale More than One Year, Number of Securities | Security 41 49
Available-for-Sale, Gross Unrealized Loss $ (580) $ (2,332)
Available-for-Sale, Estimated Fair Value $ 69,147 $ 106,264
Available-for-Sale, Number of Securities | Security 43 52
Debt securities    
Summary of Investment Holdings [Line Items]    
Available-for-Sale Within One Year, Gross Unrealized Loss $ 0 $ 0
Available-for-Sale Within One Year, Estimated Fair Value $ 0 $ 0
Available-for-Sale Within One Year, Number of Securities | Security 0 0
Available-for-Sale More than One Year, Gross Unrealized Loss $ (19) $ (97)
Available-for-Sale More than One Year, Estimated Fair Value $ 4,480 $ 7,402
Available-for-Sale More than One Year, Number of Securities | Security 2 3
Available-for-Sale, Gross Unrealized Loss $ (19) $ (97)
Available-for-Sale, Estimated Fair Value $ 4,480 $ 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 $ (22) $ (285)
Available-for-Sale Within One Year, Estimated Fair Value $ 21,255 $ 55,259
Available-for-Sale Within One Year, Number of Securities | Security 5 13
Available-for-Sale More than One Year, Gross Unrealized Loss $ (1,262) $ (8,128)
Available-for-Sale More than One Year, Estimated Fair Value $ 191,319 $ 344,484
Available-for-Sale More than One Year, Number of Securities | Security 104 158
Available-for-Sale, Gross Unrealized Loss $ (1,284) $ (8,413)
Available-for-Sale, Estimated Fair Value $ 212,574 $ 399,743
Available-for-Sale, Number of Securities | Security 109 171
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