Long-Term Debt (Tables)
 3 Months Ended
Mar. 31, 2020
Debt Disclosure [Abstract]  
Schedule of convertible senior notes
As of March 31, 2020 and December 31, 2019, the carrying amounts of the Notes on the consolidated balance sheets were calculated as follows (in thousands):
March 31, 2020December 31, 2019
Convertible senior notes, principal amount$69,242  $158,295  
Unamortized debt discount(184) (1,667) 
Unamortized debt issuance costs(36) (330) 
Convertible senior notes, net$69,022  $156,298  
Schedule of interest expense related to convertible senior notes
For the three months ended March 31, 2020 and 2019, interest expense related to the Notes consisted of the following (in thousands):
Three Months Ended March 31,
20202019
Contractual coupon interest$919  $1,201  
Debt discount amortization1,012  1,405  
Loss on extinguishment of debt166  199  
Debt issuance cost amortization200  278  
Interest expense, Notes$2,297  $3,082  
Note: Amounts may not foot due to rounding.