LONG-TERM DEBT, NET - Additional Information (Details)						1 Months Ended		12 Months Ended
	Sep. 30, 2025	Jan. 18, 2024 USD ($)	May 08, 2023 USD ($)	Feb. 18, 2020 USD ($)	Feb. 13, 2020 USD ($) $ / shares shares	Feb. 28, 2025 USD ($)	Dec. 31, 2023 USD ($)	Sep. 30, 2025 USD ($)	Sep. 30, 2024 USD ($)	Sep. 30, 2023 USD ($)	Sep. 30, 2020 USD ($)	May 09, 2019 USD ($)
Debt Instrument [Line Items]
Proceeds from sale of exchangeable senior note hedges								$ 0	$ 1,238,000	$ 0
Repayments of convertible debt								0	87,840,000	0
Write off of deferred debt issuance cost								295,000
Payments for note hedge transactions		$ 433,000			$ 28,676,000
Payments for repurchases of warrants		987,000					$ 250,000
Loss on sale of exchangeable senior note hedges		245,000						0	245,000	0
Payments for repurchases of warrants								0	552,000	0
Gain on repurchases of warrants		105,000						0	105,000	0
Debt issuance costs incurred								256,000	930,000	3,079,000
Amortization of deferred financing costs								$ 961,000	$ 1,175,000	1,514,000
Class A Common Stock
Debt Instrument [Line Items]
Warrants outstanding (in shares) | shares					3,376,391
Warrant exercise price (in USD per share) | $ / shares					$ 62.88
Warrants expired period					90 days
Proceeds from issuance of warrants					$ 14,669,000
1.0% Exchangeable Senior Notes due 2025 | Exchangeable Notes
Debt Instrument [Line Items]
Original principal amount		26,223,000		$ 138,000,000
Stated interest rate (percent)	1.00%			1.00%				1.00%
Proceeds from sale of exchangeable senior note hedges				$ 132,762,000
Debt aggregate repurchase amount		90,777,000									$ 21,000,000
Repayments of convertible debt		87,391,000				$ 26,223,000
Debt interest, repurchase amount		386,000
Write off of deferred debt issuance cost		926,000
Gain on retirement of debt		$ 2,397,000
Accrued interest						$ 131,000
Payments for repurchases of warrants							$ 119,000
Revolving lines of credit to banks under the 2023 Senior Secured Credit Facility | Line of Credit
Debt Instrument [Line Items]
Commitment fee percentage	0.15%
Revolving lines of credit to banks under the 2023 Senior Secured Credit Facility | Line of Credit | One, Two, Three, Or Six Month SOFR
Debt Instrument [Line Items]
Basis spread on variable rate (percent)	2.00%
Revolving lines of credit to banks under the 2023 Senior Secured Credit Facility | Line of Credit | One, Two, Three, Or Six Month SOFR | Minimum
Debt Instrument [Line Items]
Basis spread on variable rate (percent)			2.00%
Revolving lines of credit to banks under the 2023 Senior Secured Credit Facility | Line of Credit | One, Two, Three, Or Six Month SOFR | Maximum
Debt Instrument [Line Items]
Basis spread on variable rate (percent)			3.00%
Revolving lines of credit to banks under the 2023 Senior Secured Credit Facility | Line of Credit | SOFR Plus 1%
Debt Instrument [Line Items]
Basis spread on variable rate (percent)	1.00%
Revolving lines of credit to banks under the 2023 Senior Secured Credit Facility | Line of Credit | SOFR Plus 1% | Minimum
Debt Instrument [Line Items]
Basis spread on variable rate (percent)			1.00%
Revolving lines of credit to banks under the 2023 Senior Secured Credit Facility | Line of Credit | SOFR Plus 1% | Maximum
Debt Instrument [Line Items]
Basis spread on variable rate (percent)			2.00%
Revolving lines of credit to banks under the 2023 Senior Secured Credit Facility | Line of Credit | Revolving Credit Facility
Debt Instrument [Line Items]
Revolving line of credit borrowing capacity			$ 400,000,000									$ 450,000,000
Optional addition to borrowing capacity			$ 100,000,000
Consolidation basis			1
Debt covenant, minimum consolidated interest coverage ratio	96.8		3					96.8
Debt covenant, maximum total leverage ratio	0		5					0
Debt instrument, covenant, commitment fee multiplier			$ 400,000,000
Revolving lines of credit to banks under the 2023 Senior Secured Credit Facility | Line of Credit | Revolving Credit Facility | Minimum
Debt Instrument [Line Items]
Commitment fee percentage			0.15%
Revolving lines of credit to banks under the 2023 Senior Secured Credit Facility | Line of Credit | Revolving Credit Facility | Maximum
Debt Instrument [Line Items]
Commitment fee percentage			0.30%
Revolving lines of credit to banks under the 2023 Senior Secured Credit Facility | Line of Credit | Revolving Credit Facility | One, Two, Three, Or Six Month SOFR
Debt Instrument [Line Items]
Basis spread on variable rate (percent)			0.10%
Revolving lines of credit to banks under the 2023 Senior Secured Credit Facility | Line of Credit | Revolving Credit Facility | Adjusted Term SOFR
Debt Instrument [Line Items]
Basis spread on variable rate (percent)			0.00%
Revolving lines of credit to banks under the 2023 Senior Secured Credit Facility | Line of Credit | Revolving Credit Facility | Secured Overnight Financing Rate SOFR
Debt Instrument [Line Items]
Basis spread on variable rate (percent)			1.00%
Revolving lines of credit to banks under the 2023 Senior Secured Credit Facility | Line of Credit | Revolving Credit Facility | Base Rate
Debt Instrument [Line Items]
Basis spread on variable rate (percent)			1.00%
Revolving lines of credit to banks under the 2023 Senior Secured Credit Facility | Line of Credit | Revolving Credit Facility | Federal Funds Rate
Debt Instrument [Line Items]
Basis spread on variable rate (percent)			0.50%
2019 Senior Secured Credit Facility | Line of Credit
Debt Instrument [Line Items]
Write off of deferred debt issuance cost										$ 203,000