Annual report pursuant to Section 13 and 15(d)

Fair Value - Carrying and Fair Value Amounts (Details)

v3.10.0.1
Fair Value - Carrying and Fair Value Amounts (Details) - USD ($)
Dec. 31, 2018
Dec. 31, 2017
Carrying Amount | Level 1    
Financial Assets:    
Cash and cash equivalents $ 69,287,177 $ 15,787,069
Financial Liabilities:    
Unsecured convertible senior notes 112,777,271 112,032,083
Carrying Amount | Level 2    
Financial Liabilities:    
Long-term debt 37,261,109 40,745,354
Carrying Amount | Level 3    
Financial Assets:    
Financing notes receivable 1,300,000 1,500,000
Fair Value | Level 1    
Financial Assets:    
Cash and cash equivalents 69,287,177 15,787,069
Financial Liabilities:    
Unsecured convertible senior notes 119,378,982 139,101,660
Fair Value | Level 2    
Financial Liabilities:    
Long-term debt 37,261,109 40,745,354
Fair Value | Level 3    
Financial Assets:    
Financing notes receivable $ 1,300,000 $ 1,500,000