Supplemental Information on Oil and Natural Gas Operations (Unaudited) - Narrative (Details)	12 Months Ended
	Sep. 30, 2021 MBoe $ / Mcf $ / bbl $ / MMBTU	Sep. 30, 2020 MBoe $ / bbl $ / Mcf $ / MMBTU
Oil and Gas, Average Sale Price and Production Cost Per Unit [Line Items]
Oil and natural gas liquids, average WTI intermediate spot price (USD per bbl) | $ / bbl		43.63
Gas, average henry hub spot price (USD per mmbtu) | $ / MMBTU		1.97
Revisions	4,772	1,163
Extensions and discoveries	13,759	3,412
Result of drilling successful wells that were previously classified as unproved locations	6,564	1,404
Result of drilling successful wells offsetting locations that were previously unproven locations	7,195	2,008
Revision of previous estimate, period increase due to pricing and differentials		1,840
Revision of previous estimate, period decrease due to lease operating expenses		1,952
Revision of previous estimate, period increase due to result of better well performance that exceeded previous estimates		1,275
West Texas Intermediate (WTI)
Oil and Gas, Average Sale Price and Production Cost Per Unit [Line Items]
Oil and natural gas liquids, average WTI intermediate spot price (USD per bbl) | $ / bbl	57.64
Henry Hub
Oil and Gas, Average Sale Price and Production Cost Per Unit [Line Items]
Gas, average henry hub spot price (USD per mmbtu) | $ / MMBTU	2.94
Oil
Oil and Gas, Average Sale Price and Production Cost Per Unit [Line Items]
Percentage of reserves	64.10%	65.40%
Price (USD per bbl/mcf) | $ / bbl	55.73	41.91
Natural Gas
Oil and Gas, Average Sale Price and Production Cost Per Unit [Line Items]
Percentage of reserves	17.60%	15.80%
Price (USD per bbl/mcf) | $ / Mcf	0.99	(0.06)
NGLs
Oil and Gas, Average Sale Price and Production Cost Per Unit [Line Items]
Percentage of reserves	18.30%	18.80%
Price (USD per bbl/mcf) | $ / bbl	9.83	(1.96)