Quarterly report pursuant to Section 13 or 15(d)

Fair Value Measurements and Derivative Instrument (Current and Long-Term Debt) (Details)

v3.8.0.1
Fair Value Measurements and Derivative Instrument (Current and Long-Term Debt) (Details) - USD ($)
$ in Thousands
Sep. 30, 2017
Apr. 26, 2017
Apr. 12, 2017
Dec. 31, 2016
Senior Notes | Senior Notes Due 2021        
Debt Instrument [Line Items]        
Debt stated percentage 6.75% 6.75% 6.75%  
Senior Notes | Senior Notes Due 2025        
Debt Instrument [Line Items]        
Debt stated percentage 6.875% 6.875% 6.875%  
Carrying Amount        
Debt Instrument [Line Items]        
Current and long-term debt $ 1,336,489     $ 1,336,772
Fair Value        
Debt Instrument [Line Items]        
Current and long-term debt $ 1,421,873     $ 1,393,865