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	$ 157,646	$ 314,132
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization expense	96,065	88,374
Deferred income taxes	40,339	53,149
One-time income tax benefit	0	(161,884)
Other	6,231	6,915
Net assets / liabilities from risk management activities	(2,458)	2,030
Net change in operating assets and liabilities	(133,139)	(129,478)
Net cash provided by operating activities	164,684	173,238
Cash Flows From Investing Activities
Capital expenditures	(416,404)	(383,238)
Debt and equity securities activities, net	(963)	(135)
Other, net	2,074	2,001
Net cash used in investing activities	(415,293)	(381,372)
Cash Flows From Financing Activities
Net decrease in short-term debt	(575,780)	(110,929)
Net proceeds from equity offering	494,734	395,099
Issuance of common stock through stock purchase and employee retirement plans	4,241	5,660
Proceeds from issuance of long-term debt	596,994	0
Cash dividends paid	(58,722)	(51,837)
Debt issuance costs	(6,432)	0
Other	0	(1,518)
Net cash provided by financing activities	455,035	236,475
Net increase in cash and cash equivalents	204,426	28,341
Cash and cash equivalents at beginning of period	13,771	26,409
Cash and cash equivalents at end of period	$ 218,197	$ 54,750