Income Taxes - Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Sep. 30, 2020
Income Tax Disclosure [Abstract]
Unrealized gain on derivatives	$ 11,006	$ 0
Intangibles	222	0
Inventory	23	0
Share-based compensation	480	0
Accruals and other	578	0
Net operating loss	5,422	0
Total deferred tax assets	17,731	0
Oil and gas assets	(29,161)	(1,669)
Other fixed assets	(198)	0
Unrealized gain on derivatives	0	(165)
Total deferred tax liabilities	(29,359)	(1,834)
Deferred tax liabilities	$ (11,628)	$ (1,834)