BUSINESS COMBINATIONS - Narrative (Details) $ in Thousands			1 Months Ended	2 Months Ended	3 Months Ended	12 Months Ended
	Mar. 23, 2022 USD ($)	May 28, 2021 USD ($) shares	Jul. 31, 2022 USD ($)	Jun. 30, 2022 USD ($)	Dec. 31, 2023 USD ($)	Sep. 30, 2023 USD ($)	Sep. 30, 2022 USD ($)	Sep. 30, 2021 USD ($)
Business Acquisition [Line Items]
Consideration paid for acquisition, net of cash acquired						$ 267	$ 122,672	$ 12,549
ID R&D
Business Acquisition [Line Items]
Aggregate purchase price		$ 49,000
Initial cash payment paid for acquisition		$ 13,000
Common stock issued during acquisition (in shares) | shares		867,226
Common stock issued during acquisition, value		$ 13,900
Earnout period shift		1 year
Fair value of earnout consideration		$ 15,700
Amortization and acquisition-related costs		600				$ 2,100	$ (1,400)
Escrow deposit		4,000
Goodwill expected to be deductible for income tax purposes		$ 0
ID R&D | Performance RSUs
Business Acquisition [Line Items]
Earnout shares issuable (up to) (in shares) | shares		711,535
ID R&D | First Earnout Anniversary
Business Acquisition [Line Items]
Aggregate purchase price				$ 9,500
Initial cash payment paid for acquisition				7,700
Earnout period		1 year
Maximum payout of contingent consideration liability		$ 12,300
Earnout percentage		0.15
Value of common stock issued during acquisition				$ 1,800
ID R&D | Second Earnout Anniversary
Business Acquisition [Line Items]
Maximum payout of contingent consideration liability		$ 9,800
ID R&D | Second Earnout Anniversary | Subsequent Event
Business Acquisition [Line Items]
Aggregate purchase price					$ 8,000
Initial cash payment paid for acquisition					4,700
Value of common stock issued during acquisition					$ 3,300
HooYu
Business Acquisition [Line Items]
Initial cash payment paid for acquisition	$ 129,100		$ 400
Fair value of earnout consideration	1,600
Amortization and acquisition-related costs	$ 3,200
Percentage of voting interests acquired (as a percent)	100.00%
Payments to sellers and third-party legal and investment advisors	$ 127,500
Consideration paid for acquisition, net of cash acquired	$ 500