Quarterly report pursuant to Section 13 or 15(d)

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

v3.7.0.1
Schedule of Derivative Instruments in Statement of Financial Position, Fair Value (Details) - USD ($)
$ in Thousands
Mar. 31, 2017
Dec. 31, 2016
Derivatives, Fair Value    
Derivative Assets $ 20,032 $ 18,379
Derivative Liabilities 5,158 7,119
Forward Contracts | Commodity Contracts    
Derivatives, Fair Value    
Derivative Asset, Fair Value, Amount Not Offset Against Collateral 2,692 3,602
Derivative Liability, Fair Value, Amount Not Offset Against Collateral 3,495 5,163
Forward Contracts | Fair Value Hedges    
Derivatives, Fair Value    
Derivative Asset, Fair Value, Amount Not Offset Against Collateral 17,340 14,777
Swaps | Interest Rate Swaps    
Derivatives, Fair Value    
Derivative Asset, Fair Value, Amount Not Offset Against Collateral 0 0
Derivative Liability, Fair Value, Amount Not Offset Against Collateral 1,663 1,956
Not Designated as Hedging Instrument    
Derivatives, Fair Value    
Derivative Asset, Fair Value, Amount Not Offset Against Collateral 2,692 3,602
Derivative Liability, Fair Value, Amount Not Offset Against Collateral 3,495 5,163
Not Designated as Hedging Instrument | Accounts Receivable | Forward Contracts | Commodity Contracts    
Derivatives, Fair Value    
Derivative Asset, Fair Value, Amount Not Offset Against Collateral 2,692 3,602
Not Designated as Hedging Instrument | Accrued Liabilities | Forward Contracts | Commodity Contracts    
Derivatives, Fair Value    
Derivative Liability, Fair Value, Amount Not Offset Against Collateral 3,495 5,163
Designated as Hedging Instrument    
Derivatives, Fair Value    
Derivative Asset, Fair Value, Amount Not Offset Against Collateral 17,340 14,777
Derivative Liability, Fair Value, Amount Not Offset Against Collateral 1,663 1,956
Designated as Hedging Instrument | Other Noncurrent Assets | Forward Contracts | Fair Value Hedges    
Derivatives, Fair Value    
Derivative Asset, Fair Value, Amount Not Offset Against Collateral 17,340 14,777
Designated as Hedging Instrument | Other Noncurrent Liabilities | Swaps | Interest Rate Swaps    
Derivatives, Fair Value    
Derivative Liability, Fair Value, Amount Not Offset Against Collateral $ 1,663 $ 1,956