Subsequent events - Natural Gas Derivatives Entered Into Subsequent to Reporting Period (Details) $ in Thousands	3 Months Ended		9 Months Ended	12 Months Ended
	Mar. 31, 2020 USD ($)	Mar. 31, 2019 USD ($)	Dec. 31, 2020 MMBTU $ / MMBTU $ / bbl bbl	Dec. 31, 2022 MMBTU $ / MMBTU $ / bbl bbl	Dec. 31, 2021 MMBTU $ / MMBTU $ / bbl bbl
Subsequent Event [Line Items]
Premiums paid (received) for derivative financial instruments | $	$ 477	$ 4,016
Subsequent to End of Period
Subsequent Event [Line Items]
Premiums paid (received) for derivative financial instruments | $	$ 50,600
Commodity - Oil | Commodity | Subsequent to End of Period | Forecast | Not designated as hedges
Subsequent Event [Line Items]
Volume (Bbl)			7,177,500
Commodity - Oil | WTI NYMEX | Swap | Subsequent to End of Period | Forecast | Not designated as hedges
Subsequent Event [Line Items]
Volume (Bbl)			5,390,000	0	0
Weighted-average price (USD per unit) | $ / bbl			59.50	0	0
Commodity - Oil | Brent ICE | Swap | Subsequent to End of Period | Forecast | Not designated as hedges
Subsequent Event [Line Items]
Volume (Bbl)			1,787,500	0	2,555,000
Weighted-average price (USD per unit) | $ / bbl			63.07	0	53.19
Commodity - Oil | Brent ICE | Put | Subsequent to End of Period | Forecast | Not designated as hedges
Subsequent Event [Line Items]
Volume (Bbl)			0	0	2,463,750
Commodity - Oil | Brent ICE | Collar | Subsequent to End of Period | Forecast | Not designated as hedges
Subsequent Event [Line Items]
Volume (Bbl)			0	0	584,000
Commodity - Oil | Brent ICE to WTI NYMEX | Basis Swap | Subsequent to End of Period | Forecast | Not designated as hedges
Subsequent Event [Line Items]
Volume (Bbl)			2,695,000	0	0
Weighted-average price (USD per unit) | $ / bbl			5.09	0	0
Commodity - Natural gas | Henry Hub NYMEX | Swap | Subsequent to End of Period | Forecast | Not designated as hedges
Subsequent Event [Line Items]
Weighted-average price (USD per unit) | $ / MMBTU			2.72	0	2.59
Volume (MMBtu) | MMBTU			17,875,000	0	42,522,500
Commodity - Natural gas | Waha Inside FERC to Henry Hub NYMEX | Basis Swap | Subsequent to End of Period | Forecast | Not designated as hedges
Subsequent Event [Line Items]
Weighted-average price (USD per unit) | $ / MMBTU			(0.82)	(0.53)	(0.55)
Volume (MMBtu) | MMBTU			31,625,000	7,300,000	41,610,000
Floor | Commodity - Oil | Commodity | Subsequent to End of Period | Forecast | Not designated as hedges
Subsequent Event [Line Items]
Volume (Bbl)				0	5,602,750
Floor | Commodity - Oil | Brent ICE | Put | Subsequent to End of Period | Forecast | Not designated as hedges
Subsequent Event [Line Items]
Weighted-average price (USD per unit) | $ / bbl			0	0	55.00
Floor | Commodity - Oil | Brent ICE | Collar | Subsequent to End of Period | Forecast | Not designated as hedges
Subsequent Event [Line Items]
Weighted-average price (USD per unit) | $ / bbl			0	0	45.00
Floor | Commodity - Oil | Brent ICE | Commodity | Subsequent to End of Period | Forecast | Not designated as hedges
Subsequent Event [Line Items]
Volume (Bbl)			1,787,500	0	5,602,750
Weighted-average price (USD per unit) | $ / bbl			63.07	0	53.13
Ceiling | Commodity - Oil | Commodity | Subsequent to End of Period | Forecast | Not designated as hedges
Subsequent Event [Line Items]
Volume (Bbl)			7,177,500	0	3,139,000
Ceiling | Commodity - Oil | Brent ICE | Collar | Subsequent to End of Period | Forecast | Not designated as hedges
Subsequent Event [Line Items]
Weighted-average price (USD per unit) | $ / bbl			0	0	59.50
Ceiling | Commodity - Oil | Brent ICE | Commodity | Subsequent to End of Period | Forecast | Not designated as hedges
Subsequent Event [Line Items]
Volume (Bbl)			1,787,500	0	3,139,000
Weighted-average price (USD per unit) | $ / bbl			63.07	0	54.37