FAIR VALUE MEASUREMENT OF FINANCIAL INSTRUMENTS - Schedule of Assets Measured at Fair Value (Details) - Recurring Fair Value Measurements - USD ($) $ in Thousands	Jun. 30, 2023	Sep. 30, 2022
Assets
Short-term investments:	$ 72,609	$ 117,101
Non-qualified supplemental savings plan	15,183	14,301
Debt security investment in Galileo	35,001	33,000
Other debt securities	2,181	565
Total investments	219,758	195,236
Liabilities
Contingent consideration	8,580	4,022
ADNOC Drilling
Assets
Equity investment	154,770	147,370
Tamboran Resources Limited
Assets
Equity investment	12,623
Level 1
Assets
Short-term investments:	20,888	18,837
Non-qualified supplemental savings plan	15,183	14,301
Debt security investment in Galileo	0
Other debt securities	0	0
Total investments	182,576	161,671
Liabilities
Contingent consideration	0	0
Level 1 \| ADNOC Drilling
Assets
Equity investment	154,770	147,370
Debt security investment in Galileo		0
Level 1 \| Tamboran Resources Limited
Assets
Equity investment	12,623
Level 2
Assets
Short-term investments:	51,721	98,264
Non-qualified supplemental savings plan	0	0
Debt security investment in Galileo	0	0
Other debt securities	0	0
Total investments	0	0
Liabilities
Contingent consideration	0	0
Level 2 \| ADNOC Drilling
Assets
Equity investment	0	0
Level 2 \| Tamboran Resources Limited
Assets
Equity investment	0
Level 3
Assets
Short-term investments:	0	0
Non-qualified supplemental savings plan	0	0
Equity investment		0
Debt security investment in Galileo	35,001	33,000
Other debt securities	2,181	565
Total investments	37,182	33,565
Liabilities
Contingent consideration	8,580	4,022
Level 3 \| ADNOC Drilling
Assets
Equity investment	0
Level 3 \| Tamboran Resources Limited
Assets
Equity investment	0
Corporate debt securities
Assets
Short-term investments:	51,721	98,264
Corporate debt securities \| Level 1
Assets
Short-term investments:	0	0
Corporate debt securities \| Level 2
Assets
Short-term investments:	51,721	98,264
Corporate debt securities \| Level 3
Assets
Short-term investments:	0	0
U.S. government and federal agency securities
Assets
Short-term investments:	20,888	18,837
U.S. government and federal agency securities \| Level 1
Assets
Short-term investments:	20,888	18,837
U.S. government and federal agency securities \| Level 2
Assets
Short-term investments:	0	0
U.S. government and federal agency securities \| Level 3
Assets
Short-term investments:	$ 0	$ 0

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