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Description of Business and Summary of Significant Accounting Policies (Details 2) - USD ($)
Dec. 31, 2018
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Organization, Consolidation and Presentation of Financial Statements [Abstract]        
Cash and cash equivalents $ 13,673,308 $ 17,399,636 $ 20,519,294  
Restricted cash - current 40,075 34,733  
Restricted cash – long term 391,131 390,940  
Cash and cash equivalent and restricted cash $ 14,104,514 $ 17,790,576 $ 20,554,027 $ 25,678,006