CONSOLIDATED STATEMENTS OF STOCKHOLDERS’ EQUITY - USD ($) $ in Thousands	Total	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	Non- controlling Interest	Accumulated Other Comprehensive Income (Loss)
Beginning balance (in shares) at Sep. 30, 2022				14,212,000	1,430,000
Beginning 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	(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)				(64,000)
Repurchase and retirement of Class A common stock	(1,579)			$ (1)		(760)	(818)
Currency translation adjustment	9							1	8
Ending balance (in shares) at Sep. 30, 2023				14,420,000	1,430,000
Ending balance at Sep. 30, 2023	414,078			$ 144	$ 14	193,018	165,432	55,469	1
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	(6,176)						(5,705)	(471)
Distributions to members	(5,415)						(102)	(5,313)
Establishment of liabilities under tax receivable agreement and related changes to deferred tax assets associated with increase in tax basis	1,868					1,868
Shares issued upon vesting of equity-based awards, net of tax withholding (in shares)				208,000
Shares issued upon vesting of equity-based awards, net of tax withholding	(2,641)			$ 2		(2,643)
Shares issued as part of employee stock purchase plan (in shares)				59,000
Shares issued as part of employee stock purchase plan	1,520			$ 1		1,519
Equity-based compensation	8,443					8,443
Purchase of non-controlling interest	(18,840)					716		(19,556)
Currency translation adjustment	(18)							(2)	(16)
Change in fair value of interest rate swaps, net of reclassification adjustment	(2,066)							(184)	(1,882)
Ending balance (in shares) at Sep. 30, 2024		14,686,696	1,429,940	14,687,000	1,430,000
Ending balance at Sep. 30, 2024	390,753			$ 147	$ 14	202,921	159,625	29,943	(1,897)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	(116,230)						(114,582)	(1,648)
Distributions to members	(275)						(89)	(186)
Exchange of B shares for A shares (in shares)		1,429,940		1,430,000	1,430,000
Exchange of B shares for A shares	0			$ 14	$ (14)	28,295		(28,598)	303
Establishment of liabilities under tax receivable agreement and related changes to deferred tax assets associated with increase in tax basis	(575)					(575)
Shares issued upon vesting of equity-based awards, net of tax withholding (in shares)				164,000
Shares issued upon vesting of equity-based awards, net of tax withholding	(1,846)			$ 2		(1,848)
Shares issued as part of employee stock purchase plan (in shares)				93,000
Shares issued as part of employee stock purchase plan	1,187			$ 1		1,186
Equity-based compensation	10,499					10,499
Repurchase and retirement of Class A common stock (in shares)		0
Currency translation adjustment	(52)							2	(54)
Change in fair value of interest rate swaps, net of reclassification adjustment	1,492							487	1,005
Ending balance (in shares) at Sep. 30, 2025		16,373,991	0	16,374,000	0
Ending balance at Sep. 30, 2025	$ 284,953			$ 164	$ 0	$ 240,478	$ 44,954	$ 0	$ (643)