Discontinued Operations and Disposal Groups - Statement of Operations (Details) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
	Mar. 01, 2021	Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2021	Mar. 31, 2020	Mar. 10, 2021
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Loss from discontinued operations before income taxes		$ (18,631)	$ 0	$ (18,631)	$ 0
Income tax benefit		25	0	25	0
Loss on discontinued operations		(18,606)	$ 0	(18,606)	$ 0
Kansas Properties
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Consideration from discontinued operations						$ 3,500
Kansas Properties | Discontinued Operations, Disposed of by Sale
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Consideration from discontinued operations						$ 3,500
Closing costs	$ 200
Total revenues		0
Lease operating expenses		115
Goodwill, impairment loss				$ 18,516
Total expenses		18,631
Loss from discontinued operations before income taxes		(18,631)
Income tax benefit		25
Loss on discontinued operations		(18,606)
Kansas Properties | Discontinued Operations, Disposed of by Sale | Oil and natural gas sales, net
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Total revenues		$ 0