CONSOLIDATED CONDENSED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	3 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
OPERATING ACTIVITIES:
Net income (loss)	$ 500,106	$ (35,063)
Adjustment for loss from discontinued operations	536	509
Income (loss) from continuing operations	500,642	(34,554)
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Depreciation and amortization	143,267	133,847
Amortization of debt discount and debt issuance costs	266	263
Provision for bad debt	53	2,350
Stock-based compensation	7,087	5,901
Income from asset sales	(5,565)	(842)
Deferred income tax benefit	(503,744)	(17,073)
Other	3,799	10
Change in assets and liabilities:
Accounts receivable	(53,778)	46,048
Inventories	(1,862)	(1,721)
Prepaid expenses and other	(8,562)	7,288
Accounts payable	(8,997)	15,883
Accrued liabilities	15,324	(69,733)
Deferred income taxes	1,987	2,550
Other noncurrent liabilities	(17,645)	(15,827)
Net cash provided by operating activities from continuing operations	72,272	74,390
Net cash used in operating activities from discontinued operations	(57)	(19)
Net cash provided by operating activities	72,215	74,371
INVESTING ACTIVITIES:
Capital expenditures	(91,698)	(82,127)
Purchase of short-term investments	(16,183)	(15,025)
Payment for acquisition of business, net of cash acquired	(47,832)
Proceeds from sale of short-term investments	18,120	13,900
Proceeds from asset sales	8,749	1,209
Net cash used in investing activities	(128,844)	(82,043)
FINANCING ACTIVITIES:
Dividends paid	(76,503)	(76,176)
Proceeds from stock option exercises	892	10,253
Payments for employee taxes on net settlement of equity awards	(5,471)	(6,073)
Net cash used in financing activities	(81,082)	(71,996)
Net decrease in cash and cash equivalents	(137,711)	(79,668)
Cash and cash equivalents, beginning of period	521,375
Cash and cash equivalents, end of period	$ 383,664	$ 825,893