Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Cash flows from operating activities:
Net income	$ 18,959	$ 500,106
Adjustment for (income) loss from discontinued operations	(10,595)	536
Income from continuing operations	8,364	500,642
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	141,460	143,267
Amortization of debt discount and debt issuance costs	329	266
Provision for bad debt	873	53
Stock-based compensation	7,158	7,087
Loss on investment securities	42,844
Gain from sale of assets	(5,545)	(5,565)
Deferred income tax (benefit) expense	1,107	(503,744)
Other	168	3,799
Change in assets and liabilities increasing (decreasing) cash:
Accounts receivable	19,700	(53,778)
Inventories of materials and supplies	(1,858)	(1,862)
Prepaid expenses and other	(209)	(2,672)
Accounts payable	8,012	(8,997)
Accrued liabilities	(2,919)	16,824
Deferred income tax liability	(306)	1,987
Other noncurrent liabilities	(9,670)	(17,645)
Net cash provided by operating activities from continuing operations	209,508	79,662
Net cash used in operating activities from discontinued operations	(26)	(57)
Net cash provided by operating activities	209,482	79,605
Cash flows from investing activities:
Capital expenditures	(196,094)	(91,698)
Purchase of short-term investments	(31,324)	(16,183)
Payment for acquisition of business, net of cash acquired	(2,781)	(47,832)
Proceeds from sale of short-term investments	31,860	18,120
Proceeds from asset sales	11,609	8,749
Net cash used in investing activities	(186,730)	(128,844)
Cash flows from financing activities:
Dividends paid	(78,122)	(76,503)
Debt issuance costs paid	(3,912)
Proceeds from stock option exercises	1,954	892
Payments for employee taxes on net settlement of equity awards	(6,267)	(5,471)
Payment of contingent consideration from acquisition of business		(1,500)
Net cash used in financing activities	(86,347)	(82,582)
Net decrease in cash and cash equivalents and restricted cash	(63,595)	(131,821)
Cash and cash equivalents and restricted cash, beginning of period	326,185	560,509
Cash and cash equivalents and restricted cash, end of period	262,590	428,688
Cash paid during the period:
Interest paid	6,140	75
Income tax paid, net	5,710	2,673
Changes in accounts payable and accrued liabilities related to purchases of property, plant and equipment	$ 8,708	$ (4,448)