CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	3 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Cash Flows From Operating Activities
Net income	$ 311,292	$ 271,860
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization expense	164,608	146,020
Deferred income taxes	44,108	29,693
Other	(16,839)	(17,508)
Net assets / liabilities from risk management activities	5,589	218
Net change in other operating assets and liabilities	(263,478)	(241,383)
Net cash provided by operating activities	245,280	188,900
Cash Flows From Investing Activities
Capital expenditures	(769,650)	(795,660)
Debt and equity securities activities, net	(78)	(2,472)
Other, net	5,353	5,621
Net cash used in investing activities	(764,375)	(792,511)
Cash Flows From Financing Activities
Net decrease in short-term debt	(241,933)	(184,967)
Net proceeds from equity issuances	254,022	220,000
Issuance of common stock through stock purchase and employee retirement plans	3,746	3,779
Proceeds from issuance of long-term debt	898,275	797,258
Cash dividends paid	(119,898)	(104,552)
Debt issuance costs	(8,920)	(7,864)
Net cash provided by financing activities	785,292	723,654
Net increase in cash and cash equivalents and restricted cash and cash equivalents	266,197	120,043
Cash and cash equivalents and restricted cash and cash equivalents at beginning of period	19,248	51,554
Cash and cash equivalents and restricted cash and cash equivalents at end of period	$ 285,445	$ 171,597