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Derivative Financial Instruments - Summary of Open Commodity Derivative Contracts (Details)
$ in Thousands
1 Months Ended 3 Months Ended
Apr. 25, 2018
MMBTU
$ / MMBTU
Mar. 31, 2018
USD ($)
MMBTU
$ / MMBTU
Dec. 31, 2017
USD ($)
Derivative [Line Items]      
Liability, Fair Value | $   $ (21,036)  
Assets, Fair Value | $   25,118 $ 16,865
Liability, Fair Value | $ [1]   (2,418)  
Liability, Fair Value | $   (23,454)  
Assets, Fair Value | $   $ 32,815  
Commodity Derivative Contract Fixed Price Swaps | Natural Gas      
Derivative [Line Items]      
Type   Fixed price swaps  
Commodity Derivative Contract Fixed Price Swaps Two | Natural Gas | Derivative Contract, Liabillity      
Derivative [Line Items]      
Commodity Reference Price   NYMEX-Henry Hub  
Remaining Contract Period   Nov - Dec 2018  
Volume -MMBTU/Day | MMBTU   290,000  
Average Price/MMBTU | $ / MMBTU   2.87  
Liability, Fair Value | $   $ (1,485)  
Commodity Derivative Contract Fixed Price Swaps Three | Natural Gas | Derivative Contract, Liabillity      
Derivative [Line Items]      
Commodity Reference Price   NYMEX-Henry Hub  
Remaining Contract Period   Nov 2018 - Mar 2019  
Volume -MMBTU/Day | MMBTU   350,000  
Average Price/MMBTU | $ / MMBTU   2.95  
Liability, Fair Value | $   $ (2,734)  
Commodity Derivative Contract Fixed Price Swaps Four | Natural Gas | Derivative Contract, Liabillity      
Derivative [Line Items]      
Commodity Reference Price   NYMEX-Henry Hub  
Remaining Contract Period   Jan - Mar 2019  
Volume -MMBTU/Day | MMBTU   250,000  
Average Price/MMBTU | $ / MMBTU   3.02  
Liability, Fair Value | $   $ (441)  
Commodity Derivative Contract Fixed Price Swaps Five | Natural Gas | Derivative Contract, Liabillity      
Derivative [Line Items]      
Commodity Reference Price   NYMEX-Henry Hub  
Remaining Contract Period   Jan - Dec 2019  
Volume -MMBTU/Day | MMBTU   100,000  
Average Price/MMBTU | $ / MMBTU   2.79  
Liability, Fair Value | $   $ (217)  
Commodity Derivative Contract Fixed Price Swaps Six | Natural Gas | Derivative Contract, Liabillity      
Derivative [Line Items]      
Commodity Reference Price   NYMEX-Henry Hub  
Remaining Contract Period   Nov 2018 - Dec 2019  
Volume -MMBTU/Day | MMBTU   70,000  
Average Price/MMBTU | $ / MMBTU   2.80  
Liability, Fair Value | $   $ (377)  
Commodity Derivative Basis Swap Contracts | Natural Gas      
Derivative [Line Items]      
Type   Basis swap contracts  
Commodity Derivative Basis Swap Contracts Two | Natural Gas | Derivative Contract, Liabillity      
Derivative [Line Items]      
Commodity Reference Price   NW Rockies Basis Swap  
Remaining Contract Period   Apr 2018- Dec 2019  
Volume -MMBTU/Day | MMBTU   70,000  
Average Differential/MMBTU | $ / MMBTU   (0.78)  
Liability, Fair Value | $   $ (112)  
Crude Oil | Commodity Derivative Contract Fixed Price Swaps | Derivative Contract, Liabillity      
Derivative [Line Items]      
Type   Fixed price swaps  
Crude Oil | Commodity Derivative Contract Fixed Price Swaps One | Derivative Contract, Liabillity      
Derivative [Line Items]      
Commodity Reference Price   NYMEX-WTI  
Remaining Contract Period   Apr - Dec 2018  
Volume -MMBTU/Day | MMBTU   5,000  
Average Price/MMBTU | $ / MMBTU   60.25  
Liability, Fair Value | $   $ (4,075)  
Crude Oil | Commodity Derivative Contract Fixed Price Swaps Two | Derivative Contract, Liabillity      
Derivative [Line Items]      
Commodity Reference Price   NYMEX-WTI  
Remaining Contract Period   Jan - Mar 2019  
Volume -MMBTU/Day | MMBTU   3,000  
Average Price/MMBTU | $ / MMBTU   58.76  
Liability, Fair Value | $   $ (422)  
Crude Oil | Commodity Derivative Contract Fixed Price Swaps Three | Derivative Contract, Liabillity      
Derivative [Line Items]      
Commodity Reference Price   NYMEX-WTI  
Remaining Contract Period   Jan - June 2019  
Volume -MMBTU/Day | MMBTU   1,000  
Average Price/MMBTU | $ / MMBTU   57.70  
Liability, Fair Value | $   $ (365)  
Crude Oil | Commodity Derivative Contract Fixed Price Swaps Four | Derivative Contract, Liabillity      
Derivative [Line Items]      
Commodity Reference Price   NYMEX-WTI  
Remaining Contract Period   Jan - Dec 2019  
Volume -MMBTU/Day | MMBTU   1,000  
Average Price/MMBTU | $ / MMBTU   56.75  
Liability, Fair Value | $   $ (701)  
Crude Oil | Commodity Derivative Contract Fixed Price Swaps Five | Derivative Contract, Liabillity      
Derivative [Line Items]      
Commodity Reference Price   NYMEX-WTI  
Remaining Contract Period   Apr - June 2019  
Volume -MMBTU/Day | MMBTU   2,000  
Average Price/MMBTU | $ / MMBTU   58.21  
Liability, Fair Value | $   $ (173)  
Crude Oil | Commodity Derivative Contract Fixed Price Swaps Six | Derivative Contract, Liabillity      
Derivative [Line Items]      
Commodity Reference Price   NYMEX-WTI  
Remaining Contract Period   July - Sep 2019  
Volume -MMBTU/Day | MMBTU   1,000  
Average Price/MMBTU | $ / MMBTU   57.75  
Liability, Fair Value | $   $ (34)  
Crude Oil | Commodity Derivative Contract Fixed Price Swaps Seven | Derivative Contract, Liabillity      
Derivative [Line Items]      
Commodity Reference Price   NYMEX-WTI  
Remaining Contract Period   Apr 2018-Mar 2020  
Volume -MMBTU/Day | MMBTU   1,000  
Average Price/MMBTU | $ / MMBTU   60.05  
Liability, Fair Value | $   $ (88)  
Derivative Contract, Assets | Commodity Derivative Contract Fixed Price Swaps One | Natural Gas      
Derivative [Line Items]      
Commodity Reference Price   NYMEX-Henry Hub  
Remaining Contract Period   Apr - Oct 2018  
Volume -MMBTU/Day | MMBTU   770,000  
Average Price/MMBTU | $ / MMBTU   2.88  
Assets, Fair Value | $   $ 13,951  
Derivative Contract, Assets | Commodity Derivative Basis Swap Contracts | Natural Gas      
Derivative [Line Items]      
Commodity Reference Price   NW Rockies Basis Swap  
Remaining Contract Period   Apr - Oct 2018  
Volume -MMBTU/Day | MMBTU   140,000  
Average Differential/MMBTU | $ / MMBTU   (0.62)  
Assets, Fair Value | $   $ 4,640  
Derivative Contract, Assets | Commodity Derivative Basis Swap Contracts One | Natural Gas      
Derivative [Line Items]      
Commodity Reference Price   NW Rockies Basis Swap  
Remaining Contract Period   Apr - Dec 2018  
Volume -MMBTU/Day | MMBTU   50,000  
Average Differential/MMBTU | $ / MMBTU   (0.65)  
Assets, Fair Value | $   $ 1,506  
Derivative Contract, Assets | Commodity Derivative Basis Swap Contracts Three | Natural Gas      
Derivative [Line Items]      
Commodity Reference Price   NW Rockies Basis Swap  
Remaining Contract Period   Jan-Dec 2019  
Volume -MMBTU/Day | MMBTU   50,000  
Average Differential/MMBTU | $ / MMBTU   (0.76)  
Assets, Fair Value | $   $ 488  
Subsequent Event | Commodity Derivative Contract Fixed Price Swaps | Natural Gas      
Derivative [Line Items]      
Type Fixed price swaps    
Subsequent Event | Commodity Derivative Contract Fixed Price Swaps One | Natural Gas      
Derivative [Line Items]      
Commodity Reference Price NYMEX-Henry Hub    
Remaining Contract Period Nov 2018-Mar 2019    
Volume -MMBTU/Day | MMBTU 50,000    
Average Price/MMBTU | $ / MMBTU 2.98    
Subsequent Event | Commodity Derivative Contract Fixed Price Swaps Two | Natural Gas      
Derivative [Line Items]      
Commodity Reference Price NYMEX-Henry Hub    
Remaining Contract Period Apr 2019-Mar 2020    
Volume -MMBTU/Day | MMBTU 50,000    
Average Price/MMBTU | $ / MMBTU 2.77    
Subsequent Event | Commodity Derivative Basis Swap Contracts | Natural Gas      
Derivative [Line Items]      
Type Basis swap contracts    
Subsequent Event | Commodity Derivative Basis Swap Contracts One | Natural Gas      
Derivative [Line Items]      
Commodity Reference Price NW Rockies Basis Swap    
Remaining Contract Period May-Oct 2018    
Volume -MMBTU/Day | MMBTU 70,000    
Average Differential/MMBTU | $ / MMBTU (0.77)    
Subsequent Event | Commodity Derivative Basis Swap Contracts Two | Natural Gas      
Derivative [Line Items]      
Commodity Reference Price NW Rockies Basis Swap    
Remaining Contract Period May-Dec 2018    
Volume -MMBTU/Day | MMBTU 70,000    
Average Differential/MMBTU | $ / MMBTU (0.78)    
Subsequent Event | Commodity Derivative Basis Swap Contracts Three | Natural Gas      
Derivative [Line Items]      
Commodity Reference Price NW Rockies Basis Swap    
Remaining Contract Period Dec 2018-Mar 2019    
Volume -MMBTU/Day | MMBTU 90,000    
Average Differential/MMBTU | $ / MMBTU (0.69)    
Subsequent Event | Commodity Derivative Basis Swap Contracts Four | Natural Gas      
Derivative [Line Items]      
Commodity Reference Price NW Rockies Basis Swap    
Remaining Contract Period Jan - Mar 2019    
Volume -MMBTU/Day | MMBTU 40,000    
Average Differential/MMBTU | $ / MMBTU (0.71)    
Subsequent Event | Crude Oil | Commodity Derivative Contract Fixed Price Swaps      
Derivative [Line Items]      
Commodity Reference Price NYMEX-WTI    
Remaining Contract Period May-June 2018    
Volume -MMBTU/Day | MMBTU 500    
Average Price/MMBTU | $ / MMBTU 64.88    
Subsequent Event | Crude Oil | Commodity Derivative Contract Fixed Price Swaps One      
Derivative [Line Items]      
Commodity Reference Price NYMEX-WTI    
Remaining Contract Period June 2018    
Volume -MMBTU/Day | MMBTU 400    
Average Price/MMBTU | $ / MMBTU 66.40    
Subsequent Event | Crude Oil | Commodity Derivative Contract Fixed Price Swaps Two      
Derivative [Line Items]      
Commodity Reference Price NYMEX-WTI    
Remaining Contract Period July-Sep 2018    
Volume -MMBTU/Day | MMBTU 500    
Average Price/MMBTU | $ / MMBTU 65.23    
Subsequent Event | Crude Oil | Commodity Derivative Contract Fixed Price Swaps Three      
Derivative [Line Items]      
Commodity Reference Price NYMEX-WTI    
Remaining Contract Period Oct-Dec 2018    
Volume -MMBTU/Day | MMBTU 500    
Average Price/MMBTU | $ / MMBTU 63.25    
Subsequent Event | Crude Oil | Commodity Derivative Contract Fixed Price Swaps Four      
Derivative [Line Items]      
Commodity Reference Price NYMEX-WTI    
Remaining Contract Period July-Sep 2019    
Volume -MMBTU/Day | MMBTU 1,000    
Average Price/MMBTU | $ / MMBTU 59.80    
[1] Included in other long-term obligations in the Consolidated Balance Sheet.