Quarterly report pursuant to Section 13 or 15(d)

Debt - Notes (Details)

v3.10.0.1
Debt - Notes (Details) - USD ($)
$ in Thousands
6 Months Ended
Jun. 30, 2018
Jun. 30, 2017
Debt Instrument [Roll Forward]    
Amortization of debt issuance costs $ 99 $ 112
Senior Notes    
Debt Instrument [Roll Forward]    
2033 Senior Notes, beginning balance 31,850  
Discount, beginning balance (2,565)  
Debt issuance cost, beginning balance (125)  
Total, beginning balance 29,160  
Amortization of debt discount 1,109  
Amortization of debt issuance costs 74  
Amortization of debt discount and debt issuance costs 1,183  
2033 Senior Notes, ending balance 31,850  
Discount, ending balance (1,456)  
Debt issuance cost, ending balance (51)  
Total, ending balance $ 30,343