Income Taxes - Components (Details) - USD ($) $ in Thousands		3 Months Ended		6 Months Ended
	Feb. 26, 2021	Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2021	Mar. 31, 2020
Current income tax expense:
Federal		$ 780	$ 0	$ 780	$ 0
State		363	0	(2)	0
Total current income tax expense		1,143	0	778	0
Deferred income tax expense:
Federal		14,006	0	14,006	0
State		(918)	0	(1,068)	0
Total deferred income tax expense	$ 13,600	13,088	0	12,938	0
Total income tax expense		$ 14,231	$ 0	$ 13,716	$ 0