Summary of Significant Accounting Policies - Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2021	Mar. 31, 2020
Disaggregation of Revenue [Line Items]
Total Revenues	$ 37,259	$ 25,406	$ 60,273	$ 54,955
Oil and natural gas sales, net
Disaggregation of Revenue [Line Items]
Total Revenues	36,659	24,356	59,073	52,855
Oil
Disaggregation of Revenue [Line Items]
Total Revenues	30,784	24,598	52,891	53,396
Natural gas
Disaggregation of Revenue [Line Items]
Total Revenues	4,516	(93)	4,635	(271)
Natural gas liquids
Disaggregation of Revenue [Line Items]
Total Revenues	$ 1,359	$ (149)	$ 1,547	$ (270)