Annual report pursuant to Section 13 and 15(d)

Derivative Financial Instruments - Summary of Open Commodity Derivative Contracts (Details)

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Derivative Financial Instruments - Summary of Open Commodity Derivative Contracts (Details)
12 Months Ended
Dec. 31, 2018
MMBTU
$ / Derivative
bbl
N Y M E X Crude Oil Swap | Open Crude Oil Derivative Contracts One  
Derivatives Fair Value [Line Items]  
Termination Period May 2020
Notional Quantity (Bbls/day) 1,500 [1]
Notional Quantity (Bbls) 775,500 [1]
Strike Price | $ / Derivative 60.80
N Y M E X Crude Oil Swap | Open Crude Oil Derivative Contracts Two  
Derivatives Fair Value [Line Items]  
Termination Period May 2020
Notional Quantity (Bbls/day) 5,000 [1]
Notional Quantity (Bbls) 2,585,000 [1]
Strike Price | $ / Derivative 61.00
N Y M E X Crude Oil Swap | Open Crude Oil Derivative Contracts Three  
Derivatives Fair Value [Line Items]  
Termination Period May 2020
Notional Quantity (Bbls/day) 3,500 [1]
Notional Quantity (Bbls) 1,809,500 [1]
Strike Price | $ / Derivative 60.85
NYMEX Crude Oil Calls | Bought  
Derivatives Fair Value [Line Items]  
Termination Period May 2020
Notional Quantity (Bbls/day) 10,000 [1]
Notional Quantity (Bbls) 5,170,000 [1]
Strike Price | $ / Derivative 61.00
NYMEX Natural Gas Two Way Collars  
Derivatives Fair Value [Line Items]  
Termination Period June 2019
Notional Quantity (MMBtu/day) | MMBTU 50,000 [2]
Notional Quantity (MMBtu) | MMBTU 7,500,000 [2]
NYMEX Natural Gas Two Way Collars | Bought | Put Option  
Derivatives Fair Value [Line Items]  
Strike Price | $ / Derivative 2.49
NYMEX Natural Gas Two Way Collars | Sold | Call Option  
Derivatives Fair Value [Line Items]  
Strike Price | $ / Derivative 3.975
[1] Bbls = Barrels
[2] MMBtu = Million British Thermal Units