XML 43 R31.htm IDEA: XBRL DOCUMENT v3.19.1
Derivative Financial Instruments - Schedule of Location and Fair Value Amounts of All Derivative Instruments (Details) - Derivatives Not Designated as Hedging Contracts - Commodity Contracts - USD ($)
$ in Thousands
Mar. 31, 2019
Dec. 31, 2018
Derivative asset - current    
Derivative Asset [Abstract]    
Gross Recognized Assets $ 14,262 $ 48,662
Gross Amounts Offset, Assets (7,657) (4,774)
Total financial assets 6,605 43,888
Derivative liability - current    
Derivative Liability [Abstract]    
Gross Recognized Liabilities 9,861 5,302
Gross Amounts Offset, Liabilities (7,657) (4,774)
Total financial liabilities 2,204 528
Derivative asset - noncurrent    
Derivative Asset [Abstract]    
Gross Recognized Assets 8,597 23,605
Gross Amounts Offset, Assets (2,297) (2,484)
Total financial assets 6,300 21,121
Derivative liability - noncurrent    
Derivative Liability [Abstract]    
Gross Recognized Liabilities 3,664 4,375
Gross Amounts Offset, Liabilities (2,297) (2,484)
Total financial liabilities $ 1,367 $ 1,891