Quarterly report pursuant to Section 13 or 15(d)

Debt - Convertible Debt Information (Details)

v3.8.0.1
Debt - Convertible Debt Information (Details) - USD ($)
3 Months Ended
May 23, 2016
Mar. 31, 2018
Mar. 31, 2017
Dec. 31, 2017
Jun. 29, 2015
Debt Instrument [Line Items]          
Repurchases of convertible debt $ 1,000,000        
Convertible Senior Notes Due 2020 [Member]          
Debt Instrument [Line Items]          
Amount of underwriter's discount   $ 1,662,526   $ 1,847,254  
Convertible Debt [Member]          
Debt Instrument [Line Items]          
Amount of underwriter's discount   $ 3,700,000      
Effective percentage   7.70% 7.70%    
Convertible Debt [Member] | Convertible Senior Notes Due 2020 [Member]          
Debt Instrument [Line Items]          
Face amount   $ 115,000,000     $ 115,000,000.0
Debt instrument coupon rate   7.00%   7.00% 7.00%