SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES, RELATED RISKS AND UNCERTAINTIES - Narrative (Details) $ / shares in Units, $ in Thousands, shares in Millions		1 Months Ended	12 Months Ended
	Jan. 16, 2025	Oct. 31, 2022 USD ($) shares	Sep. 30, 2025 USD ($) geographical_area $ / shares shares	Sep. 30, 2024 USD ($) $ / shares	Sep. 30, 2023 USD ($) $ / shares
Summary Of Significant Accounting Policies [Line Items]
Restricted cash			$ 29,100	$ 1,300,000
Additional cash and cash equivalents restricted at the election of management for potential insurance claims			27,400	68,900
Inventory valuation reserves			93,500	19,500
Depository beneficial interests		0.50%
Convertible notes			$ 9,400
Convertible notes (in shares) \| shares			0.5
Receivables			$ 782,644	418,604
Contract liability			81,213	29,052	$ 28,882
Drilling services			3,678,660	2,746,128	2,862,677
Early termination revenue			2,300	13,400	2,300
Net income			$ (163,695)	$ 344,165	$ 434,100
Basic (in dollars per share) \| $ / shares			$ (1.66)	$ 3.43	$ 4.18
Diluted (in dollars per share) \| $ / shares			$ (1.66)	$ 3.43	$ 4.16
Underwriting expenses			$ 39,900	$ 11,400	$ 12,500
Casualty insurance premiums			42,700	37,600	39,700
Premium revenues and expenses			69,200	61,200	67,400
Stop-loss medical expenses			20,700	15,500	10,600
Operating revenues			$ 3,746,013	2,756,607	2,872,421
Number of geographical areas operating \| geographical_area			1
Investee
Summary Of Significant Accounting Policies [Line Items]
Receivables			$ 700	5,000
Contract liability			3,900	3,900
Drilling services			16,100	$ 14,100
Expected revenue			26,300
Investment in Tamboran
Summary Of Significant Accounting Policies [Line Items]
Payments to acquire investments		$ 14,100
Investment shares acquired (in shares) \| shares		106.0
Intangible Assets, Amortization Period
Summary Of Significant Accounting Policies [Line Items]
Amortization			15,600
Net income			$ (12,400)
Basic (in dollars per share) \| $ / shares			$ (0.12)
Diluted (in dollars per share) \| $ / shares			$ (0.12)
Customer relationships
Summary Of Significant Accounting Policies [Line Items]
Weighted average useful life			9 years	15 years
Saudi Arabia
Summary Of Significant Accounting Policies [Line Items]
Operating revenues			$ 261,747	$ 0	0
Operating Revenues \| Geographic Concentration Risk \| International Locations
Summary Of Significant Accounting Policies [Line Items]
Concentration percentage			33.80%	7.20%
Concentration percentage				27.00%
Operating Revenues \| Geographic Concentration Risk \| International Locations \| Middle East
Summary Of Significant Accounting Policies [Line Items]
Concentration percentage			13.90%
Largest Drilling Customer \| Customer Concentration Risk
Summary Of Significant Accounting Policies [Line Items]
Operating revenues			$ 451,300	$ 302,600
Largest Drilling Customer \| Operating Revenues \| Customer Concentration Risk
Summary Of Significant Accounting Policies [Line Items]
Concentration percentage			12.00%	11.00%
Reimbursements Received for Out-of-Pocket Expenses
Summary Of Significant Accounting Policies [Line Items]
Drilling services			$ 431,200	$ 334,600	$ 345,500
Minimum
Summary Of Significant Accounting Policies [Line Items]
Weighted average useful life			1 year
Lease term, lessee			1 year
Deductible per occurrence			$ 1,000
Maximum
Summary Of Significant Accounting Policies [Line Items]
Weighted average useful life			16 years
Lease term, lessee			15 years
Deductible per occurrence			$ 10,000
KCA Deutag Acquisition
Summary Of Significant Accounting Policies [Line Items]
Restricted cash				$ 1,200,000
KCA Deutag Acquisition \| Operating Revenues \| Geographic Concentration Risk \| International Locations \| Middle East
Summary Of Significant Accounting Policies [Line Items]
Concentration percentage				1.00%
KCA Deutag Acquisition \| Operating Revenues \| Geographic Concentration Risk \| International Locations \| Saudi Arabia
Summary Of Significant Accounting Policies [Line Items]
Concentration percentage			7.00%
KCA Deutag
Summary Of Significant Accounting Policies [Line Items]
Inventory valuation reserves			$ 74,700
Operating period	258 days		365 days
KCA Deutag \| Customer relationships
Summary Of Significant Accounting Policies [Line Items]
Weighted average useful life			2 years

Helmerich & Payne, Inc. 10-K