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           PARENT COMPANY FINANCIAL INFORMATION (Tables)
  
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        12 Months Ended | 
      
      
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           Dec. 31, 2014 
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        | Condensed Financial Information of Parent Company Only Disclosure [Abstract] | 
         
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        | Condensed Balance Sheets | 
        
    CONDENSED BALANCE SHEETS  (In Thousands)     |       |        |    December  31, 2014   |        |    December 31,  2013   |        |     |   ASSETS   |        |        |        |        |        |        |        |     |   Cash and due from banks   |        |    $   |    61,611   |        |    $   |    2,562   |        |     |   Investment in subsidiary   |        |        |    366,609   |        |        |    314,489   |        |     |   Other assets   |        |        |    51   |        |        |    194   |        |     |   Total assets   |        |    $   |    428,271   |        |    $   |    317,245   |        |     |       |        |        |        |        |        |        |        |     |   LIABILITIES AND STOCKHOLDERS' EQUITY   |        |        |        |        |        |        |        |     |   Liabilities:   |        |        |        |        |        |        |        |     |   Other borrowings   |        |    $   |    19,973   |        |    $   |    19,940   |        |     |   Other liabilities   |        |        |    1,337   |        |        |    113   |        |     |   Total liabilities   |        |        |    21,310   |        |        |    20,053   |        |     |   Stockholders' equity:   |        |        |        |        |        |        |        |     |    Preferred stock, Series A Senior Non-Cumulative Perpetual, par value $.001 (liquidation preference $1,000), net of discount; 40,000 shares authorized, 40,000 shares issued and outstanding at December 31, 2014 and 2013   |        |        |    39,958   |        |        |    39,958   |        |     |   Common stock, par value $.001 per share; 50,000,000 shares authorized; 24,801,518 shares issued and outstanding at December 31, 2014 and 22,050,036 shares issued and outstanding at December 31, 2013   |        |        |    25   |        |        |    7   |        |     |   Additional paid-in capital   |        |        |    185,397   |        |        |    123,325   |        |     |   Retained earnings   |        |        |    177,091   |        |        |    130,011   |        |     |   Accumulated other comprehensive income   |        |        |    4,490   |        |        |    3,891   |        |     |   Total stockholders' equity   |        |        |    406,961   |        |        |    297,192   |        |     |   Total liabilites and stockholders' equity   |        |    $   |    428,271   |        |    $   |    317,245   |        |          
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        | Condensed Statements of Income | 
        
    CONDENSED STATEMENTS OF INCOME  FOR THE YEARS ENDED DECEMBER 31,  (In Thousands)     |       |        |    2014   |        |    2013   |        |    2012   |        |     |   Income:   |        |        |        |        |        |        |        |        |        |        |     |   Dividends received from subsidiary   |        |    $   |    12,000   |        |    $   |    4,750   |        |    $   |    -   |        |     |   Other income   |        |        |    -   |        |        |    1   |        |        |    41   |        |     |   Total income   |        |        |    12,000   |        |        |    4,751   |        |        |    41   |        |     |   Expense:   |        |        |        |        |        |        |        |        |        |        |     |   Other expenses   |        |        |    1,183   |        |        |    1,147   |        |        |    1,594   |        |     |   Total expenses   |        |        |    1,183   |        |        |    1,147   |        |        |    1,594   |        |     |   Equity in undistributed earnings of subsidiary   |        |        |    41,529   |        |        |    37,997   |        |        |    35,998   |        |     |   Net income   |        |        |    52,346   |        |        |    41,601   |        |        |    34,445   |        |     |   Dividends on preferred stock   |        |        |    400   |        |        |    400   |        |        |    400   |        |     |   Net income available to common stockholders   |        |        |    51,946   |        |        |    41,201   |        |        |    34,045   |        |          
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        | Statement of Cash Flows | 
        
    STATEMENTS OF CASH FLOW  FOR THE YEARS ENDED DECEMBER 31,  (In Thousands)     |       |        |    2014   |        |    2013   |        |    2012   |        |     |   Operating activities   |        |        |        |        |        |        |        |        |        |        |     |   Net income   |        |    $   |    52,346   |        |    $   |    41,601   |        |    $   |    34,445   |        |     |   Adjustments to reconcile net income to net cash used in operating activities:   |        |        |        |        |        |        |        |        |        |        |     |   Other   |        |        |    165   |        |        |    (224)   |        |        |    878   |        |     |   Equity in undistributed earnings of subsidiary   |        |        |    (41,529)   |        |        |    (37,997)   |        |        |    (35,998)   |        |     |   Net cash (used in) provided by operating activities   |        |        |    10,982   |        |        |    3,380   |        |        |    (675)   |        |     |   Investing activities   |        |        |        |        |        |        |        |        |        |        |     |   Investment in subsidiary   |        |        |    -   |        |        |    (10,499)   |        |        |    -   |        |     |   Net cash used in investing activities   |        |        |    -   |        |        |    (10,499)   |        |        |    -   |        |     |   Financing activities   |        |        |        |        |        |        |        |        |        |        |     |   Proceeds from other borrowings   |        |        |    -   |        |        |    -   |        |        |    19,917   |        |     |   Repayment of subordinated debentures   |        |        |    -   |        |        |    -   |        |        |    (15,464)   |        |     |   Proceeds from issuance of common stock, net   |        |        |    52,076   |        |        |    10,499   |        |        |    112   |        |     |   Dividends paid on common stock   |        |        |    (3,609)   |        |        |    (3,682)   |        |        |    (3,134)   |        |     |   Dividends paid on preferred stock   |        |        |    (400)   |        |        |    (400)   |        |        |    (400)   |        |     |   Net cash provided by financing activities   |        |        |    48,067   |        |        |    6,417   |        |        |    1,031   |        |     |   Increase (decrease) in cash and cash equivalents   |        |        |    59,049   |        |        |    (702)   |        |        |    356   |        |     |   Cash and cash equivalents at beginning of year   |        |        |    2,562   |        |        |    3,264   |        |        |    2,908   |        |     |   Cash and cash equivalents at end of year   |        |    $   |    61,611   |        |    $   |    2,562   |        |    $   |    3,264   |       
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