Significant Accounting Policies - Additional Information (Details) $ in Thousands	12 Months Ended
	Sep. 30, 2021 USD ($) state reportable_unit	Sep. 30, 2020 USD ($) reportable_unit
Summary Of Accounting Policies [Line Items]
Weighted average cost inventory amount	$ 46,100	$ 33,700
FIFO inventory amount	7,600	$ 4,800
Amount company is liable for per occurrence	$ 500
Number of reporting units | reportable_unit	1	5
Alabama, Florida, Georgia, North Carolina And South Carolina
Summary Of Accounting Policies [Line Items]
Number of states | state	4
Minimum
Summary Of Accounting Policies [Line Items]
Amount company is liable for per occurrence	$ 100
Stop-loss insurance purchased	100
Maximum
Summary Of Accounting Policies [Line Items]
Amount company is liable for per occurrence	500
Stop-loss insurance purchased	$ 160