INVESTMENTS - Fair Value of Investments Measured on Recurring Basis (Details) - USD ($) $ in Thousands	Jun. 30, 2024	Sep. 30, 2023
Assets:
Short-term investments:	$ 38,718	$ 74,700
Long-term investments:	10,157	1,304
Total assets at fair value	48,875	76,004
Liabilities:
Acquisition-related contingent consideration	0	7,976
Total liabilities at fair value		7,976
U.S. Treasury
Assets:
Short-term investments:	3,790	40,254
Long-term investments:		1,304
Commercial paper
Assets:
Short-term investments:	15,711
U.S. Government and agency securities, short-term
Assets:
Short-term investments:	6,718
Corporate debt securities
Assets:
Short-term investments:	12,499	34,446
Long-term investments:	10,157
Quoted Prices in Active Markets (Level 1)
Assets:
Short-term investments:	3,790	40,254
Long-term investments:	0	1,304
Total assets at fair value	3,790	41,558
Liabilities:
Acquisition-related contingent consideration		0
Total liabilities at fair value		0
Quoted Prices in Active Markets (Level 1) | U.S. Treasury
Assets:
Short-term investments:	3,790	40,254
Long-term investments:		1,304
Quoted Prices in Active Markets (Level 1) | Commercial paper
Assets:
Short-term investments:	0
Quoted Prices in Active Markets (Level 1) | U.S. Government and agency securities, short-term
Assets:
Short-term investments:	0
Quoted Prices in Active Markets (Level 1) | Corporate debt securities
Assets:
Short-term investments:	0	0
Long-term investments:	0
Significant Other Observable Inputs (Level 2)
Assets:
Short-term investments:	34,928	34,446
Long-term investments:	10,157	0
Total assets at fair value	45,085	34,446
Liabilities:
Acquisition-related contingent consideration		7,976
Total liabilities at fair value		7,976
Significant Other Observable Inputs (Level 2) | U.S. Treasury
Assets:
Short-term investments:	0	0
Long-term investments:		0
Significant Other Observable Inputs (Level 2) | Commercial paper
Assets:
Short-term investments:	15,711
Significant Other Observable Inputs (Level 2) | U.S. Government and agency securities, short-term
Assets:
Short-term investments:	6,718
Significant Other Observable Inputs (Level 2) | Corporate debt securities
Assets:
Short-term investments:	12,499	34,446
Long-term investments:	10,157
Significant Unobservable Inputs (Level 3)
Assets:
Short-term investments:	0	0
Long-term investments:	0	0
Total assets at fair value	0	0
Liabilities:
Acquisition-related contingent consideration
Total liabilities at fair value		0
Significant Unobservable Inputs (Level 3) | U.S. Treasury
Assets:
Short-term investments:	0	0
Long-term investments:		0
Significant Unobservable Inputs (Level 3) | Commercial paper
Assets:
Short-term investments:	0
Significant Unobservable Inputs (Level 3) | U.S. Government and agency securities, short-term
Assets:
Short-term investments:	0
Significant Unobservable Inputs (Level 3) | Corporate debt securities
Assets:
Short-term investments:	0	$ 0
Long-term investments:	$ 0