Annual report pursuant to Section 13 and 15(d)

Derivative Instruments and Hedging Activities (Schedule of Derivative Instruments in Statement of Financial Position, Fair Value) (Details)

v3.10.0.1
Derivative Instruments and Hedging Activities (Schedule of Derivative Instruments in Statement of Financial Position, Fair Value) (Details) - USD ($)
$ in Thousands
Dec. 31, 2018
Dec. 31, 2017
Offsetting Assets and Liabilities [Line Items]    
Derivative Assets $ 65,114 $ 406
Derivative Liabilities (17,920) (29,028)
Not Designated as Hedging Instrument    
Offsetting Assets and Liabilities [Line Items]    
Derivative Assets 65,114 406
Derivative Liabilities (17,920) (29,028)
Not Designated as Hedging Instrument | Current Assets    
Offsetting Assets and Liabilities [Line Items]    
Derivative asset, fair value, gross asset 78,091 406
Derivative asset, fair value, gross liability (12,977) 0
Derivative Assets 65,114 406
Not Designated as Hedging Instrument | Current Liabilities    
Offsetting Assets and Liabilities [Line Items]    
Derivative liability, fair value, gross liability (23,457) (27,744)
Derivative liability, fair value, gross asset 12,977 0
Derivative Liabilities (10,480) (27,744)
Not Designated as Hedging Instrument | Non-current Liabilities    
Offsetting Assets and Liabilities [Line Items]    
Derivative liability, fair value, gross liability (7,440) (1,284)
Derivative liability, fair value, gross asset 0 0
Derivative Liabilities $ (7,440) $ (1,284)