Summary of Significant Accounting Policies - Revenue (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
Disaggregation of Revenue [Line Items]
Total Revenues	$ 151,036	$ 76,933
Oil and natural gas sales, net
Disaggregation of Revenue [Line Items]
Total Revenues	148,636	73,133
Oil
Disaggregation of Revenue [Line Items]
Total Revenues	136,421	74,895
Natural Gas
Disaggregation of Revenue [Line Items]
Total Revenues	7,500	(1,267)
Natural gas liquids
Disaggregation of Revenue [Line Items]
Total Revenues	$ 4,715	$ (495)