Summary of Significant Accounting Policies - Accounts Receivable (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Sep. 30, 2021
Accounting Policies [Abstract]
Oil, natural gas and NGL sales	$ 25,379	$ 17,008
Joint interest accounts receivable	379	413
Other accounts receivable	24	52
Total accounts receivable	$ 25,782	$ 17,473