XML 37 R24.htm IDEA: XBRL DOCUMENT v3.7.0.1
Investments (Details) - USD ($)
Mar. 31, 2017
Dec. 31, 2016
Mar. 31, 2016
Dec. 31, 2015
Cash        
Cash $ 4,947,113 $ 6,249,703    
Cash equivalents        
FDIC insured deposits and money market funds 28,713,805 24,978,489    
Cash and cash equivalents 33,660,918 31,228,192 $ 40,156,947 $ 15,431,622
Short-term Investments        
Short-term investments (due within 1 year)        
Available-for-sale Securities 93,901,236 106,979,224    
Available-for-sale Securities, Amortized Cost Basis 93,955,113 107,020,420    
Short-term Investments | U.S. government treasury obligations        
Short-term investments (due within 1 year)        
Available-for-sale Securities 69,996,135 86,053,755    
Available-for-sale Securities, Amortized Cost Basis 70,047,072 86,078,622    
Short-term Investments | Corporate obligations        
Short-term investments (due within 1 year)        
Available-for-sale Securities 23,905,101 20,925,469    
Available-for-sale Securities, Amortized Cost Basis 23,908,041 20,941,799    
Level 1        
Cash        
Cash 4,947,113 6,249,703    
Cash equivalents        
FDIC insured deposits and money market funds 28,713,805 24,978,489    
Cash and cash equivalents 33,660,918 31,228,192    
Level 1 | Short-term Investments        
Short-term investments (due within 1 year)        
Available-for-sale Securities 69,996,135 86,053,755    
Level 1 | Short-term Investments | U.S. government treasury obligations        
Short-term investments (due within 1 year)        
Available-for-sale Securities 69,996,135 86,053,755    
Level 2 | Short-term Investments        
Short-term investments (due within 1 year)        
Available-for-sale Securities 23,905,101 20,925,469    
Level 2 | Short-term Investments | Corporate obligations        
Short-term investments (due within 1 year)        
Available-for-sale Securities $ 23,905,101 $ 20,925,469