FAIR VALUE MEASUREMENT OF FINANCIAL INSTRUMENTS - Schedule of Assets Measured at Fair Value (Details) - Recurring Fair Value Measurements - USD ($) $ in Thousands	Dec. 31, 2022	Sep. 30, 2022
Assets
Short-term investments:	$ 118,457	$ 117,101
Non-qualified supplemental savings plan	15,627	14,301
Debt security investment in Galileo	33,000	33,000
Other debt securities	107	565
Total investments	195,092	195,236
Liabilities
Contingent consideration	3,780	4,022
ADNOC Drilling
Assets
Equity investment	129,130	147,370
Tamboran Resources Limited
Assets
Equity investment	17,228
Level 1
Assets
Short-term investments:	18,711	18,837
Non-qualified supplemental savings plan	15,627	14,301
Debt security investment in Galileo	0
Other debt securities	0
Total investments	161,985	161,671
Liabilities
Contingent consideration	0	0
Level 1 \| ADNOC Drilling
Assets
Equity investment	129,130	147,370
Level 1 \| Tamboran Resources Limited
Assets
Equity investment	17,228
Level 2
Assets
Short-term investments:	99,746	98,264
Non-qualified supplemental savings plan	0	0
Debt security investment in Galileo	0	0
Other debt securities	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
Debt security investment in Galileo	33,000	33,000
Other debt securities	107	565
Total investments	33,107	33,565
Liabilities
Contingent consideration	3,780	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:	99,746	98,264
Corporate debt securities \| Level 1
Assets
Short-term investments:	0	0
Corporate debt securities \| Level 2
Assets
Short-term investments:	99,746	98,264
Corporate debt securities \| Level 3
Assets
Short-term investments:	0	0
U.S. government and federal agency securities
Assets
Short-term investments:	18,711	18,837
U.S. government and federal agency securities \| Level 1
Assets
Short-term investments:	18,711	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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