Summary of Significant Accounting Policies - Accrued Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Sep. 30, 2020
Accounting Policies [Abstract]
Accrued capital expenditures	$ 9,718	$ 2,964
Accrued lease operating expenses	2,428	1,617
Accrued general and administrative costs	4,375	2,125
Accrued dividends on preferred units	0	903
Other accrued expenditures	2,834	1,079
Total accrued liabilities	$ 19,355	$ 8,688

Amount of expenses incurred but not yet paid classified as other, due within one year or the normal operating cycle, if longer.

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-Name Accounting Standards Codification
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