XML 108 R75.htm IDEA: XBRL DOCUMENT v3.19.1
Long-term debt (Principal Outstanding) (Details) - USD ($)
$ in Thousands
Dec. 31, 2018
Dec. 31, 2017
Debt Instrument [Line Items]    
Principal outstanding $ 636,248  
2027 Notes    
Debt Instrument [Line Items]    
Annual interest rate (as a percentage) 5.875%  
Principal outstanding $ 265,000 $ 265,000
2023 Notes    
Debt Instrument [Line Items]    
Annual interest rate (as a percentage) 6.625%  
Principal outstanding $ 348,069 $ 348,069