Summary of Significant Accounting Policies - Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Disaggregation of Revenue [Line Items]
Total Revenues	$ 42,149	$ 6,019	$ 102,422	$ 60,974
Oil and natural gas sales, net
Disaggregation of Revenue [Line Items]
Total Revenues	41,549	4,969	100,622	57,824
Oil
Disaggregation of Revenue [Line Items]
Total Revenues	39,504	6,153	92,395	59,548
Natural gas
Disaggregation of Revenue [Line Items]
Total Revenues	957	(738)	5,592	(1,009)
Natural gas liquids
Disaggregation of Revenue [Line Items]
Total Revenues	$ 1,088	$ (446)	$ 2,635	$ (715)