Quarterly report pursuant to Section 13 or 15(d)

Debt - Convertible Debt Information (Details)

v3.19.1
Debt - Convertible Debt Information (Details)
3 Months Ended 12 Months Ended
Jan. 16, 2019
USD ($)
shares
May 23, 2016
USD ($)
Mar. 31, 2019
USD ($)
$ / shares
Mar. 31, 2018
USD ($)
Dec. 31, 2018
USD ($)
$ / shares
shares
Jun. 29, 2015
USD ($)
Debt Instrument [Line Items]            
Capital stock non-convertible, par value (in dollars per share) | $ / shares     $ 0.001   $ 0.001  
Loss on extinguishment of debt     $ 5,039,731 $ 0    
Convertible Senior Notes Due 2020 [Member]            
Debt Instrument [Line Items]            
Amount of underwriter's discount     566,173   $ 1,108,342  
Convertible Debt [Member]            
Debt Instrument [Line Items]            
Interest expense     1,548,448 2,191,797    
Write off of debt discount     132,910 184,728    
Write off of deferred debt costs     8,681 $ 12,069    
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%
Repurchases of convertible debt $ 19,800,000 $ 1,000,000        
Amount converted $ 43,800,000       $ 42,000  
Shares issued in conversion | shares 837,040       1,271  
Conversion ratio     30.3030      
Debt principal amount     $ 1,000      
Capital stock non-convertible, par value (in dollars per share) | $ / shares         $ 0.001  
Conversion price (in dollars per share) | $ / shares     $ 33.00      
Interest expense $ 315,000   $ 1,406,857 $ 1,995,000    
Convertible debt outstanding     70,200,000      
Loss on extinguishment of debt     5,000,000      
Write off of debt discount     409,000      
Write off of deferred debt costs     $ 27,000