FAIR VALUE MEASUREMENT - Fair Value of Investments Measured on Recurring Basis (Details) - USD ($) $ in Thousands	Mar. 31, 2025	Sep. 30, 2024
Assets:
Short-term investments:	$ 31,472	$ 36,884
Long-term investments:	16,211	11,410
Total assets at fair value	47,683	48,294
U.S. Treasury
Assets:
Short-term investments:		3,836
Commercial paper
Assets:
Short-term investments:	10,130	15,984
U.S. Government and agency securities, short-term
Assets:
Short-term investments:	979
U.S. Government and agency securities, long-term | Long Term Investments
Assets:
Long-term investments:	1,499
Corporate debt securities
Assets:
Short-term investments:	20,363	17,064
Long-term investments:	14,712	11,410
Quoted Prices in Active Markets (Level 1)
Assets:
Short-term investments:	0	0
Long-term investments:	0	0
Total assets at fair value	0	0
Quoted Prices in Active Markets (Level 1) | U.S. Treasury
Assets:
Short-term investments:		0
Quoted Prices in Active Markets (Level 1) | Commercial paper
Assets:
Short-term investments:	0	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) | U.S. Government and agency securities, long-term | Long Term Investments
Assets:
Long-term investments:	0
Quoted Prices in Active Markets (Level 1) | Corporate debt securities
Assets:
Short-term investments:	0	0
Long-term investments:	0	0
Significant Other Observable Inputs (Level 2)
Assets:
Short-term investments:	31,472	36,884
Long-term investments:	16,211	11,410
Total assets at fair value	47,683	48,294
Significant Other Observable Inputs (Level 2) | U.S. Treasury
Assets:
Short-term investments:		3,836
Significant Other Observable Inputs (Level 2) | Commercial paper
Assets:
Short-term investments:	10,130	15,984
Significant Other Observable Inputs (Level 2) | U.S. Government and agency securities, short-term
Assets:
Short-term investments:	979
Significant Other Observable Inputs (Level 2) | U.S. Government and agency securities, long-term | Long Term Investments
Assets:
Long-term investments:	1,499
Significant Other Observable Inputs (Level 2) | Corporate debt securities
Assets:
Short-term investments:	20,363	17,064
Long-term investments:	14,712	11,410
Significant Unobservable Inputs (Level 3)
Assets:
Short-term investments:	0	0
Long-term investments:	0	0
Total assets at fair value	0	0
Significant Unobservable Inputs (Level 3) | U.S. Treasury
Assets:
Short-term investments:		0
Significant Unobservable Inputs (Level 3) | Commercial paper
Assets:
Short-term investments:	0	0
Significant Unobservable Inputs (Level 3) | U.S. Government and agency securities, short-term
Assets:
Short-term investments:	0
Significant Unobservable Inputs (Level 3) | U.S. Government and agency securities, long-term | Long Term Investments
Assets:
Long-term investments:	0
Significant Unobservable Inputs (Level 3) | Corporate debt securities
Assets:
Short-term investments:	0	0
Long-term investments:	$ 0	$ 0