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           Income Taxes - Domestic and foreign income taxes (Details) (USD $) 
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        12 Months Ended | ||
|---|---|---|---|
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           Dec. 31, 2013 
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           Dec. 31, 2012 
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           Dec. 31, 2011 
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| Income Tax Disclosure [Abstract] | |||
| Domestic | $ 7,704,867 | $ 29,400,084 | $ 43,255,574 | 
| Foreign | (4,945,999) | (4,793,198) | 924,531 | 
| Income before provision for income taxes | $ 2,758,868 | $ 24,606,886 | $ 44,180,105 | 
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- Definition 
          The portion of earnings or loss from continuing operations before income taxes that is attributable to domestic operations. Reference 1: http://www.xbrl.org/2003/role/presentationRef 
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- Definition 
          The portion of earnings or loss from continuing operations before income taxes that is attributable to foreign operations, which is defined as Income or Loss generated from operations located outside the entity's country of domicile. Reference 1: http://www.xbrl.org/2003/role/presentationRef 
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- Definition 
          Sum of operating profit and nonoperating income or expense before Income or Loss from equity method investments, income taxes, extraordinary items, and noncontrolling interest. Reference 1: http://www.xbrl.org/2003/role/presentationRef 
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- Details 
          
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