CONSOLIDATED STATEMENTS OF STOCKHOLDERS' AND MEMBERS' EQUITY - USD ($) shares in Thousands, $ in Thousands	Members Equity [Member]	Common Stock [Member] Class A Common Stock [Member]	Common Stock [Member] Class B Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Noncontrolling Interest [Member]	Total
Beginning balance at Sep. 30, 2017							$ 71,695
Increase (Decrease) in Temporary Equity [Roll Forward]
Non-controlling interest in subsidiary							0
Net (loss) income							0
Distributions to members							0
Accumulated unpaid preferred returns							7,737
Preferred issuance costs							(93)
Accretion of redeemable preferred and issuance costs							626
Ending balance at Sep. 30, 2018							79,965
Beginning balance at Sep. 30, 2017	$ 26,312	$ 0	$ 0	$ 0	$ 0	$ 1,763	28,075
Beginning balance (in shares) at Sep. 30, 2017		0	0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Non-controlling interest in parent	0	$ 0	$ 0	0	0	2,500	2,500
Net (loss) income	1,116	0	0	0	0	830	1,946
Distributions to members	(3,256)	0	0	0	0	0	(3,256)
Accumulated unpaid preferred returns	(7,737)	0	0	0	0	0	(7,737)
Accretion of redeemable preferred and issuance costs	(626)	0	0	0	0	0	(626)
Equity-based compensation	154	0	0	0	0	0	154
Ending balance at Sep. 30, 2018	15,963	$ 0	$ 0	0	0	5,093	21,056
Ending balance (in shares) at Sep. 30, 2018		0	0
Increase (Decrease) in Temporary Equity [Roll Forward]
Net (loss) income							0
Distributions to members							(3,364)
Accumulated unpaid preferred returns							8,768
Accretion of redeemable preferred and issuance costs							649
Ending balance at Sep. 30, 2019							86,018
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net (loss) income	35,657	$ 0	$ 0	0	0	1,606	37,263
Distributions to members	(10,587)	0	0	0	0	(500)	(11,087)
Accumulated unpaid preferred returns	(8,768)	0	0	0	0	0	(8,768)
Accretion of redeemable preferred and issuance costs	(649)	0	0	0	0	0	(649)
Equity-based compensation	154	0	0	0	0	0	154
Ending balance at Sep. 30, 2019	31,770	$ 0	$ 0	0	0	6,199	37,969
Ending balance (in shares) at Sep. 30, 2019		0	0
Ending balance at Sep. 30, 2020							0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net (loss) income							48,508
Ending balance at Sep. 30, 2020	$ 0	$ 104	$ 46	$ 105,947	$ 16,757	$ 50,433	$ 173,287
Ending balance (in shares) at Sep. 30, 2020		10,392	4,583