Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Jun. 30, 2016	Jun. 30, 2015
Cash flows from operating activities:
Net income	$ 261,023	$ 281,879
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation	124,964	129,637
Amortization	2,407	5,179
Provision for doubtful accounts	4,619	3,337
Deferred income tax benefit	(378)	(3,453)
Share-based compensation expense	8,224	9,277
Asset impairment	64,753	60,777
Loss on sale of assets	(71)	15,362
(Gain) on extinguishment of debt	(58,863)	0
Other, net	(1,137)	0
Changes in assets and liabilities:
Accounts receivable	121,964	(17,917)
Income tax receivable	511	(3,868)
Inventories of materials and supplies	12,988	(16,917)
Prepaid expenses, deferred costs and other current assets	19,377	13,274
Deferred costs and other assets	(1,019)	(341)
Accounts payable	(33,674)	(17,511)
Accrued liabilities	(3,274)	24,049
Income tax payable	(376)	(5,450)
Deferred credits and other liabilities	(6,623)	6,291
Net cash provided by operating activities	515,415	483,605
Cash flows from investing activities:
Capital expenditures	(198,248)	(420,077)
Proceeds from sale of assets	20,813	2,339
Net cash used in investing activities	(177,435)	(417,738)
Cash flows from financing activities:
Proceeds from borrowing of long-term debt	45,000	225,000
Principal repayments on long-term debt	(290,110)	(250,000)
Repayments on short-term debt, net	0	(11,885)
Debt issuance costs paid	0	(3,440)
Dividends paid	(21,746)	(32,397)
Proceeds (payments) related to exercise of stock options	(930)	1,279
Windfall tax benefits from share-based payment arrangements	(14,797)	0
Net cash used by financing activities	(252,989)	(71,443)
Net increase in cash and cash equivalents	84,991	(5,576)
Cash and cash equivalents, at beginning of period	113,983	80,080
Cash and cash equivalents, at end of period	198,974	74,504
Non-cash activities:
Increase (decrease) in accounts payable and accrued liabilities related to capital expenditures	$ 7,902	$ (15,501)