Quarterly report pursuant to Section 13 or 15(d)

Debt - Convertible Debt (Details)

v3.10.0.1
Debt - Convertible Debt (Details) - USD ($)
3 Months Ended 6 Months Ended
Jun. 30, 2018
Jun. 30, 2017
Jun. 30, 2018
Jun. 30, 2017
Dec. 31, 2017
May 31, 2017
May 23, 2017
Convertible Debt [Abstract]              
Convertible notes payable, net $ 0   $ 0   $ 281,199,000    
Convertible Senior Notes | Convertible Senior Notes Due November 2022              
Convertible Debt [Abstract]              
Principal amount 345,000,000   345,000,000   345,000,000   $ 345,000,000
Unamortized discount (51,471,000)   (51,471,000)   (56,557,000)    
Unamortized debt issuance costs (6,621,000)   (6,621,000)   (7,244,000)    
Convertible notes payable, net 286,908,000   286,908,000   281,199,000 $ 282,500,000  
Equity component 61,390,000   61,390,000   $ 61,390,000 $ 62,500,000  
Interest Expense, Debt [Abstract]              
Contractual interest expense 1,294,000 $ 561,000 2,588,000 $ 561,000      
Amortization of debt discount 2,562,000 1,052,000 5,086,000 1,052,000      
Amortization of debt issuance costs 328,000 134,000 651,000 134,000      
Interest expense, net $ 4,184,000 $ 1,747,000 $ 8,325,000 $ 1,747,000