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]	Accumulated Other Comprehensive Loss [Member]	Total
Beginning balance at Sep. 30, 2019								$ 86,018
Ending balance at Sep. 30, 2020								0
Beginning balance at Sep. 30, 2019	$ 31,770	$ 0	$ 0	$ 0	$ 0	$ 6,199	$ 0	37,969
Beginning balance (in shares) at Sep. 30, 2019		0	0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net (loss) income								48,508
Currency Translation Adjustment								0
Ending balance at Sep. 30, 2020	0	$ 104	$ 46	105,947	16,757	50,433	0	173,287
Ending balance (in shares) at Sep. 30, 2020		10,392	4,583
Increase (Decrease) in Temporary Equity [Roll Forward]
Net (loss) income								0
Distributions to members								0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net (loss) income	0	$ 0	$ 0	0	79,059	37,354	0	116,413
Distributions to members	0	0	0	0	(1,160)	(8,813)	0	(9,973)
Dividends and distributions	0	0	0	0	(20,777)	(7,328)	0	(28,105)
Effect of September Offering, including underwriter exercise of option to purchase shares	0	$ 4	$ (4)	4,146	0	(4,256)	0	(110)
Effect of September Offering, including underwriter exercise of option to purchase shares (in shares)		387	(387)
Exchange of B shares for A shares	0	$ 24	$ (24)	38,485	0	(38,485)	0	0
Exchange of B shares for A shares (in shares)		2,377	(2,377)
Establishment of liabilities under tax receivable agreement and related changes to deferred tax assets associated with increases in tax basis	0	$ 0	$ 0	(4,186)	0	0	0	(4,186)
Shares issued upon vesting of equity-based awards, net of tax withholding	0	$ 1	$ 0	(803)	0	0	0	(802)
Shares issued upon vesting of equity-based awards, net of tax withholding (in shares)		85	0
Shares issued in connection with a business combination	0	$ 0	$ 0	1,495	0	0	0	1,495
Shares issued in connection with a business combination (in shares)		36	0
Adjustment to adopt Topic 842	0	$ 0	$ 0	0	1,073	0	0	1,073
Equity-based compensation	0	0	0	5,741	0	0	0	5,741
Currency Translation Adjustment								0
Ending balance at Sep. 30, 2021	0	$ 133	$ 18	150,825	74,952	28,905	0	254,833
Ending balance (in shares) at Sep. 30, 2021		13,277	1,819
Increase (Decrease) in Temporary Equity [Roll Forward]
Net (loss) income								0
Distributions to members								0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net (loss) income	0	$ 0	$ 0	0	130,944	21,667	0	152,611
Distributions to members	0	0	0	0	(784)	(3,497)	0	(4,281)
Exchange of B shares for A shares	0	$ 4	$ (4)	6,833	0	(6,833)	0	0
Exchange of B shares for A shares (in shares)		389	(389)
Establishment of liabilities under tax receivable agreement and related changes to deferred tax assets associated with increases in tax basis	0	$ 0	$ 0	(247)	0	0	0	(247)
Shares issued upon vesting of equity-based awards, net of tax withholding	0	$ 1	$ 0	(1,629)	0	0	0	(1,628)
Shares issued upon vesting of equity-based awards, net of tax withholding (in shares)		169	0
Shares issued in connection with a business combination	0	$ 4	$ 0	14,623	0	0	0	14,627
Shares issued in connection with a business combination (in shares)		387	0
Non-controlling interest in subsidiary	0	$ 0	$ 0	0	0	19,311		19,311
Equity-based compensation	0	$ 0	0	10,013	0	0	0	10,013
Repurchase and retirement of Class A common stock (in shares)		(10)
Repurchase and retirement of Class A common stock	0	$ 0	0	(122)	(232)	0	0	(354)
Currency Translation Adjustment		0	0	0	0	(1)	(7)	(8)
Ending balance at Sep. 30, 2022	$ 0	$ 142	$ 14	$ 180,296	$ 204,880	$ 59,552	$ (7)	$ 444,877
Ending balance (in shares) at Sep. 30, 2022		14,212	1,430