Quarterly report pursuant to Section 13 or 15(d)

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

v3.19.1
Securities - Available for Sale Securities, Continuous Unrealized Loss Position, Fair value (Detail)
$ in Thousands
Mar. 31, 2019
USD ($)
Security
Dec. 31, 2018
USD ($)
Security
Summary of Investment Holdings [Line Items]    
Available-for-Sale Within One Year, Gross Unrealized Loss $ 40 $ 321
Available-for-Sale Within One Year, Estimated Fair Value $ 51,089 $ 78,252
Available-for-Sale Within One Year, Number of Securities | Security 10 20
Available-for-Sale More than One Year, Gross Unrealized Loss $ 4,527 $ 8,616
Available-for-Sale More than One Year, Estimated Fair Value $ 319,053 $ 410,128
Available-for-Sale More than One Year, Number of Securities | Security 157 188
Available-for-Sale, Gross Unrealized Loss $ 4,567 $ 8,937
Available-for-Sale, Estimated Fair Value $ 370,142 $ 488,380
Available-for-Sale, Number of Securities | Security 167 208
U.S. Treasury securities    
Summary of Investment Holdings [Line Items]    
Available-for-Sale Within One Year, Gross Unrealized Loss $ 4 $ 7
Available-for-Sale Within One Year, Estimated Fair Value $ 19,773 $ 14,797
Available-for-Sale Within One Year, Number of Securities | Security 3 2
Available-for-Sale More than One Year, Gross Unrealized Loss $ 0 $ 0
Available-for-Sale More than One Year, Estimated Fair Value $ 0 $ 0
Available-for-Sale More than One Year, Number of Securities | Security 0 0
Available-for-Sale, Gross Unrealized Loss $ 4 $ 7
Available-for-Sale, Estimated Fair Value $ 19,773 $ 14,797
Available-for-Sale, Number of Securities | Security 3 2
Mortgage-backed securities    
Summary of Investment Holdings [Line Items]    
Available-for-Sale Within One Year, Gross Unrealized Loss $ 19 $ 226
Available-for-Sale Within One Year, Estimated Fair Value $ 13,442 $ 41,527
Available-for-Sale Within One Year, Number of Securities | Security 2 10
Available-for-Sale More than One Year, Gross Unrealized Loss $ 2,919 $ 5,758
Available-for-Sale More than One Year, Estimated Fair Value $ 214,791 $ 244,550
Available-for-Sale More than One Year, Number of Securities | Security 101 106
Available-for-Sale, Gross Unrealized Loss $ 2,938 $ 5,984
Available-for-Sale, Estimated Fair Value $ 228,233 $ 286,077
Available-for-Sale, Number of Securities | Security 103 116
Collateralized mortgage obligations    
Summary of Investment Holdings [Line Items]    
Available-for-Sale Within One Year, Gross Unrealized Loss $ 17 $ 59
Available-for-Sale Within One Year, Estimated Fair Value $ 17,874 $ 13,732
Available-for-Sale Within One Year, Number of Securities | Security 5 3
Available-for-Sale More than One Year, Gross Unrealized Loss $ 1,540 $ 2,273
Available-for-Sale More than One Year, Estimated Fair Value $ 92,822 $ 92,532
Available-for-Sale More than One Year, Number of Securities | Security 50 49
Available-for-Sale, Gross Unrealized Loss $ 1,557 $ 2,332
Available-for-Sale, Estimated Fair Value $ 110,696 $ 106,264
Available-for-Sale, Number of Securities | Security 55 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 $ 53 $ 97
Available-for-Sale More than One Year, Estimated Fair Value $ 7,447 $ 7,402
Available-for-Sale More than One Year, Number of Securities | Security 3 3
Available-for-Sale, Gross Unrealized Loss $ 53 $ 97
Available-for-Sale, Estimated Fair Value $ 7,447 $ 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 $ 36 $ 285
Available-for-Sale Within One Year, Estimated Fair Value $ 31,316 $ 55,259
Available-for-Sale Within One Year, Number of Securities | Security 7 13
Available-for-Sale More than One Year, Gross Unrealized Loss $ 4,512 $ 8,128
Available-for-Sale More than One Year, Estimated Fair Value $ 315,060 $ 344,484
Available-for-Sale More than One Year, Number of Securities | Security 154 158
Available-for-Sale, Gross Unrealized Loss $ 4,548 $ 8,413
Available-for-Sale, Estimated Fair Value $ 346,376 $ 399,743
Available-for-Sale, Number of Securities | Security 161 171
Municipal bonds-tax exempt    
Summary of Investment Holdings [Line Items]    
Available-for-Sale Within One Year, Gross Unrealized Loss $ 0 $ 29
Available-for-Sale Within One Year, Estimated Fair Value $ 0 $ 8,196
Available-for-Sale Within One Year, Number of Securities | Security 0 5
Available-for-Sale More than One Year, Gross Unrealized Loss $ 15 $ 488
Available-for-Sale More than One Year, Estimated Fair Value $ 3,993 $ 65,644
Available-for-Sale More than One Year, Number of Securities | Security 3 30
Available-for-Sale, Gross Unrealized Loss $ 15 $ 517
Available-for-Sale, Estimated Fair Value $ 3,993 $ 73,840
Available-for-Sale, Number of Securities | Security 3 35