Income Taxes - Additional Information (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended			6 Months Ended
	Mar. 31, 2021	Dec. 31, 2020	Mar. 31, 2020	Mar. 31, 2021	Mar. 31, 2020
Income Tax Disclosure [Abstract]
Income tax expense	$ 1,992		$ 2,612	$ 4,748	$ 6,336
Federal income tax expense	1,462		1,901	3,486	4,678
State income tax expense	$ 530		$ 711	$ 1,262	$ 1,658
Reduction in provision for other adjustments		$ 520
Reduction in provision for other adjustments, impact on diluted earnings per share (in dollars per share)		$ 0.02
Reduction in effective income tax rate	0.00%		0.00%	1.50%	0.00%