| 
           CONSOLIDATED STATEMENT OF STOCKHOLDERS' EQUITY (USD $) 
        In Thousands  | 
        
           Total 
         | 
        
           Preferred Stock [Member] 
         | 
        
           Common Stock [Member] 
         | 
        
           Additional Paid In Capital [Member] 
         | 
        
           Retained Earnings [Member] 
         | 
        
           Accumulated Other Comprehensive Income [Member] 
         | 
      
|---|---|---|---|---|---|---|
| Beginning Balance at Dec. 31, 2009 | $ 97,622 | $ 0 | $ 6 | $ 75,078 | $ 20,965 | $ 1,573 | 
| Sale Of Shares | 0 | |||||
| Other comprehensive income | 1,264 | 0 | 0 | 0 | 0 | 1,264 | 
| Stock-based compensation expense | 713 | 0 | 0 | 713 | 0 | 0 | 
| Net income | 17,378 | 0 | 0 | 0 | 17,378 | 0 | 
| Exercise of stock options, including tax benefit | 123 | 0 | 0 | 123 | 0 | 0 | 
| Sale of shares of preferred stock, net | 0 | |||||
| Preferred dividends paid | 0 | |||||
| Ending Balance at Dec. 31, 2010 | 117,100 | 0 | 6 | 75,914 | 38,343 | 2,837 | 
| Sale Of Shares | 10,159 | 0 | 0 | 10,159 | 0 | 0 | 
| Other comprehensive income | 4,105 | 0 | 0 | 0 | 0 | 4,105 | 
| Stock-based compensation expense | 975 | 0 | 0 | 975 | 0 | 0 | 
| Net income | 23,438 | 0 | 0 | 0 | 23,438 | 0 | 
| Exercise of stock options, including tax benefit | 757 | 0 | 0 | 757 | 0 | 0 | 
| Sale of shares of preferred stock, net | 39,958 | 39,958 | 0 | 0 | 0 | 0 | 
| Preferred dividends paid | (200) | 0 | 0 | 0 | (200) | 0 | 
| Ending Balance at Dec. 31, 2011 | 196,292 | 39,958 | 6 | 87,805 | 61,581 | 6,942 | 
| Other comprehensive income | 354 | 0 | 0 | 0 | 0 | 354 | 
| Stock-based compensation expense | 1,049 | 0 | 0 | 1,049 | 0 | 0 | 
| Net income | 34,445 | 0 | 0 | 0 | 34,445 | 0 | 
| Exercise of stock options, including tax benefit | 4,651 | 0 | 0 | 4,651 | 0 | 0 | 
| Preferred dividends paid | (400) | 0 | 0 | 0 | (400) | 0 | 
| Dividends paid | (3,134) | 0 | 0 | 0 | (3,134) | 0 | 
| Ending Balance at Dec. 31, 2012 | $ 233,257 | $ 39,958 | $ 6 | $ 93,505 | $ 92,492 | $ 7,296 | 
| X | ||||||||||
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- Definition 
          Value of preferred stock issued during the period. No definition available. 
  | 
        
| X | ||||||||||
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- Definition 
          This element represents the amount of recognized equity-based compensation during the period, that is, the amount recognized as expense in the income statement (or as asset if compensation is capitalized). Alternate captions include the words "stock-based compensation". Reference 1: http://www.xbrl.org/2003/role/presentationRef 
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| X | ||||||||||
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- Definition 
          Equity impact of common stock cash dividends declared by an entity during the period. This element includes paid and unpaid dividends declared during the period. Reference 1: http://www.xbrl.org/2003/role/presentationRef 
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| X | ||||||||||
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- Definition 
          Equity impact of preferred stock cash dividends declared by an entity during the period. This element includes paid and unpaid dividends declared during the period. Reference 1: http://www.xbrl.org/2003/role/presentationRef 
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| X | ||||||||||
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- Definition 
          Net of tax amount of other comprehensive income (loss) attributable to both parent entity and noncontrolling interest. Reference 1: http://www.xbrl.org/2003/role/presentationRef 
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| X | ||||||||||
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- Definition 
          The consolidated profit or loss for the period, net of income taxes, including the portion attributable to the noncontrolling interest. Reference 1: http://www.xbrl.org/2003/role/presentationRef 
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| X | ||||||||||
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- Definition 
          Total of all stockholders' equity (deficit) items, net of receivables from officers, directors, owners, and affiliates of the entity which are attributable to the parent. The amount of the economic entity's stockholders' equity attributable to the parent excludes the amount of stockholders' equity which is allocable to that ownership interest in subsidiary equity which is not attributable to the parent (noncontrolling interest, minority interest). This excludes temporary equity and is sometimes called permanent equity. Reference 1: http://www.xbrl.org/2003/role/presentationRef 
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| X | ||||||||||
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- Definition 
          Equity impact of the value of new stock issued during the period. Includes shares issued in an initial public offering or a secondary public offering. Reference 1: http://www.xbrl.org/2003/role/presentationRef 
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| X | ||||||||||
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- Definition 
          Value of stock issued as a result of the exercise of stock options. Reference 1: http://www.xbrl.org/2003/role/presentationRef 
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