Quarterly report pursuant to Section 13 or 15(d)

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

v3.7.0.1
Securities - Available for Sale Securities, Continuous Unrealized Loss Position, Fair value (Detail)
$ in Thousands
 3 Months Ended 12 Months Ended
Mar. 31, 2017
USD ($)
Security
Dec. 31, 2016
USD ($)
Security
Summary of Investment Holdings [Line Items]    
Available-for-Sale Within One Year, Gross Unrealized Loss $ 3,309 $ 4,496
Available-for-Sale Within One Year, Estimated Fair Value $ 345,987 $ 320,260
Available-for-Sale Within One Year, Number of Securities | Security 131 128
Available-for-Sale More than One Year, Gross Unrealized Loss $ 749 $ 757
Available-for-Sale More than One Year, Estimated Fair Value $ 28,061 $ 26,991
Available-for-Sale More than One Year, Number of Securities | Security 16 15
Available-for-Sale, Gross Unrealized Loss $ 4,058 $ 5,253
Available-for-Sale, Estimated Fair Value $ 374,048 $ 347,251
Available-for-Sale, Number of Securities | Security 147 143
Municipal bonds-tax exempt [Member]    
Summary of Investment Holdings [Line Items]    
Available-for-Sale Within One Year, Gross Unrealized Loss $ 860 $ 1,995
Available-for-Sale Within One Year, Estimated Fair Value $ 104,412 $ 125,004
Available-for-Sale Within One Year, Number of Securities | Security 45 54
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 $ 860 $ 1,995
Available-for-Sale, Estimated Fair Value $ 104,412 $ 125,004
Available-for-Sale, Number of Securities | Security 45 54
Municipal bonds-taxable [Member]    
Summary of Investment Holdings [Line Items]    
Available-for-Sale Within One Year, Gross Unrealized Loss $ 8 $ 9
Available-for-Sale Within One Year, Estimated Fair Value $ 1,036 $ 2,904
Available-for-Sale Within One Year, Number of Securities | Security 1 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 $ 8 $ 9
Available-for-Sale, Estimated Fair Value $ 1,036 $ 2,904
Available-for-Sale, Number of Securities | Security 1 2
Mutual funds [Member]    
Summary of Investment Holdings [Line Items]    
Available-for-Sale Within One Year, Gross Unrealized Loss $ 413 $ 413
Available-for-Sale Within One Year, Estimated Fair Value $ 21,478 $ 21,478
Available-for-Sale Within One Year, Number of Securities | Security 4 4
Available-for-Sale More than One Year, Gross Unrealized Loss $ 113 $ 109
Available-for-Sale More than One Year, Estimated Fair Value $ 914 $ 916
Available-for-Sale More than One Year, Number of Securities | Security 3 3
Available-for-Sale, Gross Unrealized Loss $ 526 $ 522
Available-for-Sale, Estimated Fair Value $ 22,392 $ 22,394
Available-for-Sale, Number of Securities | Security 7 7
Mortgage-backed securities [Member]    
Summary of Investment Holdings [Line Items]    
Available-for-Sale Within One Year, Gross Unrealized Loss $ 1,418 $ 1,345
Available-for-Sale Within One Year, Estimated Fair Value $ 149,993 $ 102,647
Available-for-Sale Within One Year, Number of Securities | Security 51 38
Available-for-Sale More than One Year, Gross Unrealized Loss $ 62 $ 112
Available-for-Sale More than One Year, Estimated Fair Value $ 7,096 $ 11,350
Available-for-Sale More than One Year, Number of Securities | Security 2 3
Available-for-Sale, Gross Unrealized Loss $ 1,480 $ 1,457
Available-for-Sale, Estimated Fair Value $ 157,089 $ 113,997
Available-for-Sale, Number of Securities | Security 53 41
Collateralized mortgage obligations [Member]    
Summary of Investment Holdings [Line Items]    
Available-for-Sale Within One Year, Gross Unrealized Loss $ 557 $ 676
Available-for-Sale Within One Year, Estimated Fair Value $ 61,622 $ 60,786
Available-for-Sale Within One Year, Number of Securities | Security 27 27
Available-for-Sale More than One Year, Gross Unrealized Loss $ 383 $ 326
Available-for-Sale More than One Year, Estimated Fair Value $ 15,888 $ 10,579
Available-for-Sale More than One Year, Number of Securities | Security 9 7
Available-for-Sale, Gross Unrealized Loss $ 940 $ 1,002
Available-for-Sale, Estimated Fair Value $ 77,510 $ 71,365
Available-for-Sale, Number of Securities | Security 36 34
U.S. government agency securities [Member]    
Summary of Investment Holdings [Line Items]    
Available-for-Sale Within One Year, Gross Unrealized Loss $ 53 $ 58
Available-for-Sale Within One Year, Estimated Fair Value $ 7,446 $ 7,441
Available-for-Sale Within One Year, Number of Securities | Security 3 3
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 $ 53 $ 58
Available-for-Sale, Estimated Fair Value $ 7,446 $ 7,441
Available-for-Sale, Number of Securities | Security 3 3
SBA loan pool securities [Member]    
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 $ 191 $ 210
Available-for-Sale More than One Year, Estimated Fair Value $ 4,163 $ 4,146
Available-for-Sale More than One Year, Number of Securities | Security 2 2
Available-for-Sale, Gross Unrealized Loss $ 191 $ 210
Available-for-Sale, Estimated Fair Value $ 4,163 $ 4,146
Available-for-Sale, Number of Securities | Security 2 2