Quarterly report pursuant to Section 13 or 15(d)

Fair Value (Details)

v3.7.0.1
Fair Value (Details) - Fair Value, Measurements, Recurring - Forward Contracts - USD ($)
$ in Thousands
Jun. 30, 2017
Dec. 31, 2016
Commodity Contracts    
Liabilities:    
Derivative Liabilities $ 662 $ 689
Fair Value Hedge    
Assets:    
Derivative Assets 5,130 4,389
Level 1 | Commodity Contracts    
Liabilities:    
Derivative Liabilities 662 689
Level 1 | Fair Value Hedge    
Assets:    
Derivative Assets 0 0
Level 2 | Commodity Contracts    
Liabilities:    
Derivative Liabilities 0 0
Level 2 | Fair Value Hedge    
Assets:    
Derivative Assets 5,130 4,389
Level 3 | Commodity Contracts    
Liabilities:    
Derivative Liabilities 0 0
Level 3 | Fair Value Hedge    
Assets:    
Derivative Assets $ 0 $ 0