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           Consolidated Statements of Shareholders' Equity (Parenthetical) (USD $) 
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        12 Months Ended | ||
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           Dec. 31, 2014 
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           Dec. 31, 2013 
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           Dec. 31, 2012 
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| Statement of Stockholders' Equity [Abstract] | |||
| Dividends ($ per common share) | $ 0.45us-gaap_CommonStockDividendsPerShareCashPaid | $ 0.10us-gaap_CommonStockDividendsPerShareCashPaid | $ 0.05us-gaap_CommonStockDividendsPerShareCashPaid | 
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- Definition 
          Aggregate dividends paid during the period for each share of common stock outstanding. Reference 1: http://www.xbrl.org/2003/role/presentationRef 
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- Details 
          
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