Quarterly report pursuant to Section 13 or 15(d)

Debt - Convertible Debt Information (Details)

v3.10.0.1
Debt - Convertible Debt Information (Details)
3 Months Ended 9 Months Ended
May 23, 2016
USD ($)
Sep. 30, 2018
USD ($)
$ / shares
shares
Sep. 30, 2017
Sep. 30, 2018
USD ($)
$ / shares
Sep. 30, 2017
Dec. 31, 2017
USD ($)
Jun. 29, 2015
USD ($)
Debt Instrument [Line Items]              
Repurchases of convertible debt $ 1,000,000            
Amount converted   $ 42,000          
Shares issued in conversion | shares   1,271          
Conversion ratio   30.3030          
Debt principal amount   $ 1,000          
Conversion price (in dollars per share) | $ / shares   $ 33.00   $ 33.00      
Convertible Senior Notes Due 2020 [Member]              
Debt Instrument [Line Items]              
Amount of underwriter's discount   $ 1,293,070   $ 1,293,070   $ 1,847,254  
Convertible Debt [Member]              
Debt Instrument [Line Items]              
Amount of underwriter's discount   $ 3,700,000   $ 3,700,000      
Effective percentage   7.70% 7.70% 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     $ 115,000,000.0
Debt instrument coupon rate   7.00%   7.00%   7.00% 7.00%