Derivatives - Commodity derivative contracts terminated (Details) - WTI NYMEX - Early Contract Termination - Crude Oil	12 Months Ended
	Dec. 31, 2019 $ / bbl bbl	Dec. 31, 2017 $ / bbl bbl
Oil puts: April 2019 - December 2019
Derivative [Line Items]
Aggregate volumes (Bbl) | bbl	5,087,500
Floor price (dollars per Bbl and MMBtu)	46.03
Ceiling price (dollars per Bbl and MMBtu)	0
Oil put: January 2020 - December 2020
Derivative [Line Items]
Aggregate volumes (Bbl) | bbl	366,000
Floor price (dollars per Bbl and MMBtu)	45.00
Ceiling price (dollars per Bbl and MMBtu)	0
Oil collars: January 2020 - December 2020
Derivative [Line Items]
Aggregate volumes (Bbl) | bbl	1,134,600
Floor price (dollars per Bbl and MMBtu)	45.00
Ceiling price (dollars per Bbl and MMBtu)	76.13
Oil swap: January 2018 - December 2018
Derivative [Line Items]
Aggregate volumes (Bbl) | bbl		1,095,000
Floor price (dollars per Bbl and MMBtu)		52.12
Ceiling price (dollars per Bbl and MMBtu)		52.12