Quarterly report pursuant to Section 13 or 15(d)

Fair Value Measurements and Derivative Instruments (Carrying amounts and fair value of the financial instruments) (Details)

v3.2.0.727
Fair Value Measurements and Derivative Instruments (Carrying amounts and fair value of the financial instruments) (Details) - USD ($)
$ in Thousands
Jun. 30, 2015
Dec. 31, 2014
Senior Notes Due 2021 | Line of Credit    
Debt Instrument [Line Items]    
Debt stated percentage 6.75%  
Senior Notes Due 2019 | Line of Credit    
Debt Instrument [Line Items]    
Debt stated percentage 6.875%  
Carrying Amount    
Debt Instrument [Line Items]    
Current and long-term debt $ 1,348,803 $ 1,036,678
Fair Value    
Debt Instrument [Line Items]    
Current and long-term debt $ 1,383,920 $ 1,055,952