UNAUDITED CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	3 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income	$ 95,173	$ 97,145
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	93,991	96,655
Asset impairment charges	0	12,097
Provision for credit loss	1,309	3,358
Stock-based compensation	7,672	8,273
Loss on investment securities	4,034	15,091
Gain on reimbursement of drilling equipment	(7,494)	(15,724)
Other gain on sale of assets	(2,443)	(2,379)
Deferred income tax expense (benefit)	(7,829)	188
Other	(856)	7,274
Change in assets and liabilities:
Accounts receivable	(28,931)	(57,896)
Inventories of materials and supplies	(7,191)	(3,007)
Prepaid expenses and other	(8,404)	(8,676)
Other noncurrent assets	(1,150)	(1,746)
Accounts payable	23,865	10,450
Accrued liabilities	19,022	20,759
Deferred income tax liability	(4)	(711)
Other noncurrent liabilities	(5,966)	4,224
Net cash provided by operating activities	174,798	185,375
CASH FLOWS FROM INVESTING ACTIVITIES:
Capital expenditures	(136,411)	(96,027)
Purchase of short-term investments	(46,250)	(41,641)
Purchase of long-term investments	(291)	(16,237)
Proceeds from sale of short-term investments	57,956	40,758
Proceeds from asset sales	11,929	30,978
Net cash used in investing activities	(113,067)	(82,169)
CASH FLOWS FROM FINANCING ACTIVITIES:
Dividends paid	(42,294)	(51,764)
Payments for employee taxes on net settlement of equity awards	(8,820)	(9,483)
Payment of contingent consideration from acquisition of business	(250)	(250)
Share repurchases	(47,364)	(39,060)
Net cash used in financing activities	(98,728)	(100,557)
Net increase (decrease) in cash and cash equivalents and restricted cash	(36,997)	2,649
Cash and cash equivalents and restricted cash, beginning of period	316,238	269,009
Cash and cash equivalents and restricted cash, end of period	279,241	271,658
Cash paid/(received) during the period:
Interest paid	927	915
Income tax paid	5,960	3,741
Income tax received	0	(25,617)
Payments for operating leases	3,262	2,474
Non-cash operating and investing activities:
Change in accounts payable and accrued liabilities related to purchases of property, plant and equipment	$ (7,611)	$ (650)