CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	9 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Cash Flows From Operating Activities
Net income	$ 564,317	$ 360,568
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization expense	268,426	234,833
Deferred income taxes	139,852	188,256
One-time income tax benefit	(165,522)	0
Gain on sale of discontinued operations	0	(12,931)
Discontinued cash flow hedging for natural gas marketing commodity contracts	0	(10,579)
Other	18,007	14,892
Net assets / liabilities from risk management activities	912	25,661
Net change in operating assets and liabilities	209,304	(55,139)
Net cash provided by operating activities	1,035,296	745,561
Cash Flows From Investing Activities
Capital expenditures	(1,088,472)	(812,148)
Acquisition	0	(86,128)
Proceeds from the sale of discontinued operations	3,000	140,253
Available-for-sale securities activities, net	(7,857)	(14,329)
Use tax refund	0	18,562
Other, net	6,105	6,435
Net cash used in investing activities	(1,087,224)	(747,355)
Cash Flows From Financing Activities
Net decrease in short-term debt	(202,968)	(571,238)
Net proceeds from equity offering	395,092	98,755
Issuance of common stock through stock purchase and employee retirement plans	15,850	22,673
Proceeds from issuance of long-term debt	0	884,911
Settlement of interest rate agreements	0	(36,996)
Interest rate agreements cash collateral	0	25,670
Repayment of long-term debt	0	(250,000)
Cash dividends paid	(160,007)	(143,075)
Debt issuance costs	0	(6,663)
Other	(1,518)	0
Net cash provided by financing activities	46,449	24,037
Net increase (decrease) in cash and cash equivalents	(5,479)	22,243
Cash and cash equivalents at beginning of period	26,409	47,534
Cash and cash equivalents at end of period	$ 20,930	$ 69,777