Income Taxes - Components (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Mar. 31, 2022	Mar. 31, 2021
Current income tax expense:
Federal	$ 768	$ 780	$ 768	$ 780
State	11	363	124	(2)
Total current income tax expense	779	1,143	892	778
Deferred income tax expense (benefit):
Federal	(2,894)	14,006	2,775	14,006
State	1	(918)	88	(1,068)
Total deferred income tax expense (benefit)	(2,893)	13,088	2,863	12,938
Total income tax expense (benefit)	$ (2,114)	$ 14,231	$ 3,755	$ 13,716