CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	6 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Cash Flows From Operating Activities
Net income	$ 574,208	$ 514,432
Adjustments to reconcile net income to net cash provided by (used in) operating activities:
Depreciation and amortization expense	261,230	233,921
Deferred income taxes	40,122	128,725
Other	(12,812)	(938)
Net assets / liabilities from risk management activities	(4,172)	(1,954)
Net change in Winter Storm Uri long-term regulatory asset (See Note 8)	0	(2,093,534)
Net change in other operating assets and liabilities	(218,092)	(182,898)
Net cash provided by (used in) operating activities	640,484	(1,402,246)
Cash Flows From Investing Activities
Capital expenditures	(1,190,029)	(845,728)
Debt and equity securities activities, net	3,758	(5,506)
Other, net	4,302	5,171
Net cash used in investing activities	(1,181,969)	(846,063)
Cash Flows From Financing Activities
Net proceeds from equity issuances	594,320	460,678
Issuance of common stock through stock purchase and employee retirement plans	8,010	8,291
Proceeds from issuance of long-term debt	798,802	2,797,346
Repayment of long-term debt	(200,000)	0
Cash dividends paid	(183,944)	(159,348)
Debt issuance costs	(8,196)	(14,155)
Other	(1,735)	0
Net cash provided by financing activities	1,007,257	3,092,812
Net increase in cash and cash equivalents	465,772	844,503
Cash and cash equivalents at beginning of period	116,723	20,808
Cash and cash equivalents at end of period	$ 582,495	$ 865,311