Derivatives - Derivative Transactions Resulting in Hedged Gas Contracts Outstanding (Details) - Forecast MMBTU in Thousands, MBbls in Thousands	3 Months Ended		12 Months Ended
	Dec. 31, 2020 MMBTU $ / bbl $ / MMBtu MBbls	Sep. 30, 2020 MMBTU $ / MMBtu $ / bbl MBbls	Dec. 31, 2021 MMBTU $ / MMBtu $ / bbl MBbls
Fixed Price Oil Swaps (Brent)
Derivative [Line Items]
Hedged volume (MBbls) | MBbls	2,208	2,208	4,678
Weighted-average price ($/Bbl) | $ / bbl	59.85	59.85	45.99
Purchased Oil Calls Options (Brent)
Derivative [Line Items]
Hedged volume (MBbls) | MBbls	276	276	0
Weighted-average price ($/Bbl) | $ / bbl	65.00	65.00	0
Fixed Price Gas Purchase Swaps (Kern, Delivered)
Derivative [Line Items]
Hedged volume (MMBtu) | MMBTU	5,060	5,060	14,580
Weighted-average price ($/MMBtu) | $ / MMBtu	2.76	2.89	2.72
Fixed Price Gas Purchase Swaps (SoCal Citygate)
Derivative [Line Items]
Hedged volume (MMBtu) | MMBTU	155	460	0
Weighted-average price ($/MMBtu) | $ / MMBtu	3.80	3.80	0