CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	3 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Cash Flows From Operating Activities
Net income	$ 271,860	$ 249,209
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization expense	146,020	127,856
Deferred income taxes	29,693	11,813
Other	(17,508)	(12,689)
Net assets / liabilities from risk management activities	218	(8,834)
Net change in other operating assets and liabilities	(241,383)	(305,531)
Net cash provided by operating activities	188,900	61,824
Cash Flows From Investing Activities
Capital expenditures	(795,660)	(684,180)
Debt and equity securities activities, net	(2,472)	2,374
Other, net	5,621	2,058
Net cash used in investing activities	(792,511)	(679,748)
Cash Flows From Financing Activities
Net decrease in short-term debt	(184,967)	0
Net proceeds from equity issuances	220,000	261,943
Issuance of common stock through stock purchase and employee retirement plans	3,779	3,918
Proceeds from issuance of long-term debt	797,258	596,142
Cash dividends paid	(104,552)	(90,411)
Debt issuance costs	(7,864)	(6,386)
Net cash provided by financing activities	723,654	765,206
Net increase in cash and cash equivalents	120,043	147,282
Cash and cash equivalents at beginning of period	51,554	116,723
Cash and cash equivalents at end of period	$ 171,597	$ 264,005