Quarterly report pursuant to Section 13 or 15(d)

Debt - Notes (Details)

v3.8.0.1
Debt - Notes (Details) - USD ($)
$ in Thousands
3 Months Ended 9 Months Ended
Sep. 30, 2017
Sep. 30, 2016
Sep. 30, 2017
Sep. 30, 2016
Debt Instrument [Roll Forward]        
Amortization of debt issuance costs     $ 168 $ 175
Change in fair value of derivative instruments $ 7,550 $ 5,701 (1,969) $ 5,889
Senior Notes        
Debt Instrument [Roll Forward]        
Embedded conversion option, beginning balance     16,736  
2033 Senior Notes, beginning balance     31,850  
Discount, beginning balance     (4,612)  
Debt issuance cost, beginning balance     (273)  
Total, beginning balance     43,701  
Amortization of debt discount     1,514  
Amortization of debt issuance costs     111  
Amortization of debt discount and debt issuance costs     1,625  
Change in fair value of derivative instruments     (3,185)  
Reclassification of embedded derivatives to equity     (13,551)  
Embedded conversion option, ending balance 0   0  
2033 Senior Notes, ending balance 31,850   31,850  
Discount, ending balance (3,098)   (3,098)  
Debt issuance cost, ending balance (162)   (162)  
Total, ending balance $ 28,590   $ 28,590