Quarterly report pursuant to Section 13 or 15(d)

Debt - Convertible Debt (Details)

v3.19.2
Debt - Convertible Debt (Details) - Convertible Senior Notes - Convertible Senior Notes Due November 2022 - USD ($)
3 Months Ended 6 Months Ended
Jun. 30, 2019
Jun. 30, 2018
Jun. 30, 2019
Jun. 30, 2018
Dec. 31, 2018
May 31, 2017
May 23, 2017
Convertible Debt [Abstract]              
Principal amount $ 345,000,000   $ 345,000,000   $ 345,000,000   $ 345,000,000.0
Unamortized discount (40,842,000)   (40,842,000)   (46,235,000)    
Unamortized debt issuance costs (5,231,000)   (5,231,000)   (5,922,000)    
Convertible notes payable, net (non current) 298,927,000   298,927,000   292,843,000    
Equity component 61,390,000   61,390,000   $ 61,390,000 $ 62,500,000  
Interest Expense, Debt [Abstract]              
Contractual interest expense 1,294,000 $ 1,294,000 2,588,000 $ 2,588,000      
Amortization of debt discount 2,717,000 2,562,000 5,393,000 5,086,000      
Amortization of debt issuance costs 348,000 328,000 691,000 651,000      
Interest expense, net $ 4,359,000 $ 4,184,000 $ 8,672,000 $ 8,325,000