INVESTMENT SECURITIES (Tables)
   | 
12 Months Ended | 
Dec. 31, 2015  | 
| Investment Securities Tables | 
 
 | 
| Schedule of amortized cost and related market value of investment securities available-for-sale | 
 Investment
Portfolio Composition. The amortized cost and related market value of investment securities at December 31 were as follows: 
  
    |   | 
      | 
    2015 | 
      | 
      | 
    2014 | 
      | 
 
    |   | 
      | 
    Amortized | 
      | 
      | 
    Unrealized | 
      | 
      | 
    Unrealized | 
      | 
      | 
    Market | 
      | 
      | 
    Amortized | 
      | 
      | 
    Unrealized | 
      | 
      | 
    Unrealized | 
      | 
      | 
    Market | 
      | 
 
    |   | 
      | 
    Cost | 
      | 
      | 
    Gains | 
      | 
      | 
    Losses | 
      | 
      | 
    Value | 
      | 
      | 
    Cost | 
      | 
      | 
    Gain | 
      | 
      | 
    Losses | 
      | 
      | 
    Value | 
      | 
 
    | Available
    for Sale | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
 
    | U.S.
    Government Treasury | 
      | 
    $ | 
    250,458 | 
      | 
      | 
    $ | 
    101 | 
      | 
      | 
    $ | 
    213 | 
      | 
      | 
    $ | 
    250,346 | 
      | 
      | 
    $ | 
    185,830 | 
      | 
      | 
    $ | 
    220 | 
      | 
      | 
    $ | 
    19 | 
      | 
      | 
    $ | 
    186,031 | 
      | 
 
    | U.S.
    Government Agency | 
      | 
      | 
    101,730 | 
      | 
      | 
      | 
    357 | 
      | 
      | 
      | 
    263 | 
      | 
      | 
      | 
    101,824 | 
      | 
      | 
      | 
    95,950 | 
      | 
      | 
      | 
    289 | 
      | 
      | 
      | 
    142 | 
      | 
      | 
      | 
    96,097 | 
      | 
 
    States
    and Political  Subdivisions | 
      | 
      | 
    88,358 | 
      | 
      | 
      | 
    103 | 
      | 
      | 
      | 
    99 | 
      | 
      | 
      | 
    88,362 | 
      | 
      | 
      | 
    48,405 | 
      | 
      | 
      | 
    65 | 
      | 
      | 
      | 
    82 | 
      | 
      | 
      | 
    48,388 | 
      | 
 
    | Mortgage-Backed
    Securities | 
      | 
      | 
    1,742 | 
      | 
      | 
      | 
    159 | 
      | 
      | 
      | 
     | 
      | 
      | 
      | 
    1,901 | 
      | 
      | 
      | 
    2,094 | 
      | 
      | 
      | 
    193 | 
      | 
      | 
      | 
     | 
      | 
      | 
      | 
    2,287 | 
      | 
 
    | Equity
    Securities(1) | 
      | 
      | 
    8,595 | 
      | 
      | 
      | 
     | 
      | 
      | 
      | 
     | 
      | 
      | 
      | 
    8,595 | 
      | 
      | 
      | 
    8,745 | 
      | 
      | 
      | 
     | 
      | 
      | 
      | 
     | 
      | 
      | 
      | 
    8,745 | 
      | 
 
    | Total | 
      | 
    $ | 
    450,883 | 
      | 
      | 
    $ | 
    720 | 
      | 
      | 
    $ | 
    575 | 
      | 
      | 
    $ | 
    451,028 | 
      | 
      | 
    $ | 
    341,024 | 
      | 
      | 
    $ | 
    767 | 
      | 
      | 
    $ | 
    243 | 
      | 
      | 
    $ | 
    341,548 | 
      | 
 
    |   | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
 
    | Held
    to Maturity | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
 
    | U.S.
    Government Treasury | 
      | 
    $ | 
    134,554 | 
      | 
      | 
    $ | 
    45 | 
      | 
      | 
    $ | 
    160 | 
      | 
      | 
    $ | 
    134,439 | 
      | 
      | 
    $ | 
    76,179 | 
      | 
      | 
    $ | 
    144 | 
      | 
      | 
    $ | 
    6 | 
      | 
      | 
    $ | 
    76,317 | 
      | 
 
    | U.S.
    Government Agency | 
      | 
      | 
    10,043 | 
      | 
      | 
      | 
    7 | 
      | 
      | 
      | 
    5 | 
      | 
      | 
      | 
    10,045 | 
      | 
      | 
      | 
    19,807 | 
      | 
      | 
      | 
    29 | 
      | 
      | 
      | 
    19 | 
      | 
      | 
      | 
    19,817 | 
      | 
 
    States
    and Political  Subdivisions | 
      | 
      | 
    15,693 | 
      | 
      | 
      | 
    38 | 
      | 
      | 
      | 
    7 | 
      | 
      | 
      | 
    15,724 | 
      | 
      | 
      | 
    26,717 | 
      | 
      | 
      | 
    36 | 
      | 
      | 
      | 
    6 | 
      | 
      | 
      | 
    26,747 | 
      | 
 
    | Mortgage-Backed
    Securities | 
      | 
      | 
    27,602 | 
      | 
      | 
      | 
    4 | 
      | 
      | 
      | 
    407 | 
      | 
      | 
      | 
    27,199 | 
      | 
      | 
      | 
    40,878 | 
      | 
      | 
      | 
    33 | 
      | 
      | 
      | 
    380 | 
      | 
      | 
      | 
    40,531 | 
      | 
 
    | Total | 
      | 
    $ | 
    187,892 | 
      | 
      | 
    $ | 
    94 | 
      | 
      | 
    $ | 
    579 | 
      | 
      | 
    $ | 
    187,407 | 
      | 
      | 
    $ | 
    163,581 | 
      | 
      | 
    $ | 
    242 | 
      | 
      | 
    $ | 
    411 | 
      | 
      | 
    $ | 
    163,412 | 
      | 
 
    |   | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
 
    | Total
    Investment Securities | 
      | 
    $ | 
    638,775 | 
      | 
      | 
    $ | 
    814 | 
      | 
      | 
    $ | 
    1,154 | 
      | 
      | 
    $ | 
    638,435 | 
      | 
      | 
    $ | 
    504,605 | 
      | 
      | 
    $ | 
    1,009 | 
      | 
      | 
    $ | 
    654 | 
      | 
      | 
    $ | 
    504,960 | 
      | 
 
 
  
    |   | 
    (1) | 
    Includes
    Federal Home Loan Bank, Federal Reserve Bank and FNBB Inc. stock recorded at cost of $3.6 million and $4.8 and $0.2 million,
    respectively, at December 31, 2015 and Federal Home Loan Bank and Federal Reserve Bank stock at $3.9 million and $4.8 million,
    respectively, at December 31, 2014. | 
 
 
 | 
| Schedule of proceeds from sale and gross realized gains and losses from the securities | 
 Investment
Sales. The total proceeds from the sale of investment securities and the gross realized gains and losses from the sale of
such securities for each of the last three years are as follows: 
  
    | (Dollars
    in Thousands) | 
      | 
      | 
    Year | 
      | 
      | 
    Total
     Proceeds | 
      | 
      | 
    Gross
     Realized Gains | 
      | 
      | 
    Gross
     Realized Losses | 
      | 
 
    |   | 
      | 
      | 
    2015 | 
      | 
      | 
    $ | 
     | 
      | 
      | 
    $ | 
     | 
      | 
      | 
    $ | 
     | 
      | 
 
    |   | 
      | 
      | 
    2014 | 
      | 
      | 
      | 
     | 
      | 
      | 
      | 
     | 
      | 
      | 
      | 
     | 
      | 
 
    |   | 
      | 
      | 
    2013 | 
      | 
      | 
    $ | 
    7,506 | 
      | 
      | 
    $ | 
    3 | 
      | 
      | 
    $ | 
     | 
      | 
 
 
 | 
| Schedule of investment securities with maturity distribution based on contractual maturities | 
 Maturity
Distribution. As of December 31, 2015, the Companys investment securities had the following maturity distribution based
on contractual maturity. Expected maturities may differ from contractual maturities because borrowers may have the right to call
or prepay obligations. Mortgage-backed securities and certain amortizing U.S. government agency securities are shown separately
since they are not due at a certain maturity date. 
  
    |   | 
      | 
    Available
    for Sale | 
      | 
      | 
    Held
    to Maturity | 
      | 
 
    | (Dollars
    in Thousands) | 
      | 
    Amortized
     Cost | 
      | 
      | 
    Market
     Value | 
      | 
      | 
    Amortized
     Cost | 
      | 
      | 
    Market
     Value | 
      | 
 
    | Due in
    one year or less | 
      | 
    $ | 
    90,331 | 
      | 
      | 
    $ | 
    90,261 | 
      | 
      | 
    $ | 
    44,267 | 
      | 
      | 
    $ | 
    44,270 | 
      | 
 
    | Due after one through
    five years | 
      | 
      | 
    280,264 | 
      | 
      | 
      | 
    280,116 | 
      | 
      | 
      | 
    116,023 | 
      | 
      | 
      | 
    115,938 | 
      | 
 
    | Mortgage-Backed Securities | 
      | 
      | 
    1,742 | 
      | 
      | 
      | 
    1,901 | 
      | 
      | 
      | 
    27,602 | 
      | 
      | 
      | 
    27,199 | 
      | 
 
    | U.S. Government Agency | 
      | 
      | 
    69,951 | 
      | 
      | 
      | 
    70,155 | 
      | 
      | 
      | 
     | 
      | 
      | 
      | 
     | 
      | 
 
    | Equity
    Securities | 
      | 
      | 
    8,595 | 
      | 
      | 
      | 
    8,595 | 
      | 
      | 
      | 
     | 
      | 
      | 
      | 
     | 
      | 
 
    | Total | 
      | 
    $ | 
    450,883 | 
      | 
      | 
    $ | 
    451,028 | 
      | 
      | 
    $ | 
    187,892 | 
      | 
      | 
    $ | 
    187,407 | 
      | 
 
 
 | 
| Schedule of investment securities with continuous unrealized loss position | 
 Other
Than Temporarily Impaired Securities. The following table summarizes the investment securities with unrealized losses at December
31, aggregated by major security type and length of time in a continuous unrealized loss position: 
  
    |   | 
      | 
    Less
    Than  12 Months | 
      | 
      | 
    Greater
    Than  12 Months | 
      | 
      | 
    Total | 
      | 
 
    | (Dollars
    in Thousands) | 
      | 
    Market
     Value | 
      | 
      | 
    Unrealized Losses | 
      | 
      | 
    Market
     Value | 
      | 
      | 
    Unrealized
     Losses | 
      | 
      | 
    Market
     Value | 
      | 
      | 
    Unrealized
     Losses | 
      | 
 
    | 2015 | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
 
    | Available
    for Sale | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
 
    | U.S. Government
    Treasury | 
      | 
    $ | 
    150,061 | 
      | 
      | 
    $ | 
    213 | 
      | 
      | 
    $ | 
     | 
      | 
      | 
    $ | 
     | 
      | 
      | 
    $ | 
    150,061 | 
      | 
      | 
    $ | 
    213 | 
      | 
 
    | U.S. Government Agency | 
      | 
      | 
    43,508 | 
      | 
      | 
      | 
    200 | 
      | 
      | 
      | 
    9,644 | 
      | 
      | 
      | 
    63 | 
      | 
      | 
      | 
    53,152 | 
      | 
      | 
      | 
    263 | 
      | 
 
    | States
    and Political Subdivisions | 
      | 
      | 
    39,608 | 
      | 
      | 
      | 
    86 | 
      | 
      | 
      | 
    5,066 | 
      | 
      | 
      | 
    13 | 
      | 
      | 
      | 
    44,674 | 
      | 
      | 
      | 
    99 | 
      | 
 
    | Total | 
      | 
      | 
    233,177 | 
      | 
      | 
      | 
    499 | 
      | 
      | 
      | 
    14,710 | 
      | 
      | 
      | 
    76 | 
      | 
      | 
      | 
    247,887 | 
      | 
      | 
      | 
    575 | 
      | 
 
    |   | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
 
    | Held
    to Maturity | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
 
    | U.S. Government Treasury | 
      | 
      | 
    92,339 | 
      | 
      | 
      | 
    160 | 
      | 
      | 
      | 
     | 
      | 
      | 
      | 
     | 
      | 
      | 
      | 
    92,339 | 
      | 
      | 
      | 
    160 | 
      | 
 
    | U.S. Government Agency | 
      | 
      | 
    5,006 | 
      | 
      | 
      | 
    5 | 
      | 
      | 
      | 
     | 
      | 
      | 
      | 
     | 
      | 
      | 
      | 
    5,006 | 
      | 
      | 
      | 
    5 | 
      | 
 
    | States and Political
    Subdivisions | 
      | 
      | 
    3,791 | 
      | 
      | 
      | 
    7 | 
      | 
      | 
      | 
     | 
      | 
      | 
      | 
     | 
      | 
      | 
      | 
    3,791 | 
      | 
      | 
      | 
    7 | 
      | 
 
    | Mortgage-Backed
    Securities | 
      | 
      | 
    13,267 | 
      | 
      | 
      | 
    185 | 
      | 
      | 
      | 
    11,889 | 
      | 
      | 
      | 
    222 | 
      | 
      | 
      | 
    25,156 | 
      | 
      | 
      | 
    407 | 
      | 
 
    | Total | 
      | 
    $ | 
    114,403 | 
      | 
      | 
    $ | 
    357 | 
      | 
      | 
    $ | 
    11,889 | 
      | 
      | 
    $ | 
    222 | 
      | 
      | 
    $ | 
    126,292 | 
      | 
      | 
    $ | 
    579 | 
      | 
 
    |   | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
 
    | 2014 | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
 
    | Available
    for Sale | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
 
    | U.S. Government Treasury | 
      | 
    $ | 
    35,838 | 
      | 
      | 
    $ | 
    19 | 
      | 
      | 
    $ | 
     | 
      | 
      | 
    $ | 
     | 
      | 
      | 
    $ | 
    35,838 | 
      | 
      | 
    $ | 
    19 | 
      | 
 
    | U.S. Government Agency | 
      | 
      | 
    18,160 | 
      | 
      | 
      | 
    54 | 
      | 
      | 
      | 
    18,468 | 
      | 
      | 
      | 
    88 | 
      | 
      | 
      | 
    36,628 | 
      | 
      | 
      | 
    142 | 
      | 
 
    | States
    and Political Subdivisions | 
      | 
      | 
    16,497 | 
      | 
      | 
      | 
    77 | 
      | 
      | 
      | 
    505 | 
      | 
      | 
      | 
    5 | 
      | 
      | 
      | 
    17,002 | 
      | 
      | 
      | 
    82 | 
      | 
 
    | Total | 
      | 
      | 
    70,495 | 
      | 
      | 
      | 
    150 | 
      | 
      | 
      | 
    18,973 | 
      | 
      | 
      | 
    93 | 
      | 
      | 
      | 
    89,468 | 
      | 
      | 
      | 
    243 | 
      | 
 
    |   | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
 
    | Held
    to Maturity | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
      | 
 
    | U.S. Government Treasury | 
      | 
      | 
    15,046 | 
      | 
      | 
      | 
    6 | 
      | 
      | 
      | 
     | 
      | 
      | 
      | 
     | 
      | 
      | 
      | 
    15,046 | 
      | 
      | 
      | 
    6 | 
      | 
 
    | U.S. Government Agency | 
      | 
      | 
    10,002 | 
      | 
      | 
      | 
    19 | 
      | 
      | 
      | 
     | 
      | 
      | 
      | 
     | 
      | 
      | 
      | 
    10,002 | 
      | 
      | 
      | 
    19 | 
      | 
 
    | States and Political
    Subdivisions | 
      | 
      | 
    3,788 | 
      | 
      | 
      | 
    6 | 
      | 
      | 
      | 
     | 
      | 
      | 
      | 
     | 
      | 
      | 
      | 
    3,788 | 
      | 
      | 
      | 
    6 | 
      | 
 
    | Mortgage-Backed
    Securities | 
      | 
      | 
    15,066 | 
      | 
      | 
      | 
    149 | 
      | 
      | 
      | 
    18,155 | 
      | 
      | 
      | 
    231 | 
      | 
      | 
      | 
    33,221 | 
      | 
      | 
      | 
    380 | 
      | 
 
    | Total | 
      | 
    $ | 
    43,902 | 
      | 
      | 
    $ | 
    180 | 
      | 
      | 
    $ | 
    18,155 | 
      | 
      | 
    $ | 
    231 | 
      | 
      | 
    $ | 
    62,057 | 
      | 
      | 
    $ | 
    411 | 
 
 
 |