CONSOLIDATED STATEMENTS OF STOCKHOLDERS’ EQUITY - USD ($) $ in Thousands	Total	Adjustment to adopt Topic 842	Class A Common Stock	Class B Common Stock	Common Stock Class A Common Stock	Common Stock Class B Common Stock	Additional Paid-in Capital	Retained Earnings	Retained Earnings Adjustment to adopt Topic 842	Non- controlling Interest	Accumulated Other Comprehensive Income (Loss)
Beginning balance (in shares) at Sep. 30, 2020					10,392,000	4,583,000
Beginning balance at Sep. 30, 2020	$ 173,287	$ 1,073			$ 104	$ 46	$ 105,947	$ 16,757	$ 1,073	$ 50,433	$ 0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net (loss) income	116,413							79,059		37,354
Distributions to members	(9,973)							(1,160)		(8,813)
Dividends and distributions	(28,105)							(20,777)		(7,328)
Effect of September Offering, including underwriter exercise of option to purchase shares (in shares)					387,000	(387,000)
Effect of September Offering, including underwriter exercise of option to purchase shares	(110)				$ 4	$ (4)	4,146			(4,256)
Exchange of B shares for A shares (in shares)					2,377,000	(2,377,000)
Exchange of B shares for A shares	0				$ 24	$ (24)	38,485			(38,485)
Establishment of liabilities under tax receivable agreement and related changes to deferred tax assets associated with increase in tax basis	(4,186)						(4,186)
Shares issued upon vesting of equity-based awards, net of tax withholding (in shares)					85,000
Shares issued upon vesting of equity-based awards, net of tax withholding	(802)				$ 1		(803)
Shares issued in connection with a business combination (in shares)					36,000
Shares issued in connection with a business combination	1,495						1,495
Equity-based compensation	5,741						5,741
Currency translation adjustment	0
Ending balance (in shares) at Sep. 30, 2021					13,277,000	1,819,000
Ending balance at Sep. 30, 2021	254,833				$ 133	$ 18	150,825	74,952		28,905	0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net (loss) income	152,611							130,944		21,667
Distributions to members	(4,281)							(784)		(3,497)
Exchange of B shares for A shares (in shares)					389,000	(389,000)
Exchange of B shares for A shares	0				$ 4	$ (4)	6,833			(6,833)
Establishment of liabilities under tax receivable agreement and related changes to deferred tax assets associated with increase in tax basis	(247)						(247)
Shares issued upon vesting of equity-based awards, net of tax withholding (in shares)					169,000
Shares issued upon vesting of equity-based awards, net of tax withholding	(1,628)				$ 1		(1,629)
Shares issued in connection with a business combination (in shares)					387,000
Shares issued in connection with a business combination	14,627				$ 4		14,623
Non-controlling interest in subsidiary	19,311									19,311
Equity-based compensation	10,013						10,013
Repurchase and retirement of Class A common stock (in shares)					(10,000)
Repurchase and retirement of Class A common stock	(354)						(122)	(232)
Currency translation adjustment	(8)									(1)	(7)
Ending balance (in shares) at Sep. 30, 2022			14,211,621	1,429,940	14,212,000	1,430,000
Ending balance at Sep. 30, 2022	444,877				$ 142	$ 14	180,296	204,880		59,552	(7)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net (loss) income	(39,111)							(38,592)		(519)
Distributions to members	(3,603)							(38)		(3,565)
Establishment of liabilities under tax receivable agreement and related changes to deferred tax assets associated with increase in tax basis	4,402						4,402
Shares issued upon vesting of equity-based awards, net of tax withholding (in shares)					186,000
Shares issued upon vesting of equity-based awards, net of tax withholding	(1,971)				$ 2		(1,973)
Shares issued as part of employee stock purchase plan (in shares)					86,000
Shares issued as part of employee stock purchase plan	2,092				$ 1		2,091
Equity-based compensation	8,962						8,962
Repurchase and retirement of Class A common stock (in shares)			(63,353)		(64,000)
Repurchase and retirement of Class A common stock	(1,579)		$ (1,600)		$ (1)		(760)	(818)
Currency translation adjustment	9									1	8
Ending balance (in shares) at Sep. 30, 2023			14,420,129	1,429,940	14,420,000	1,430,000
Ending balance at Sep. 30, 2023	$ 414,078				$ 144	$ 14	$ 193,018	$ 165,432		$ 55,469	$ 1