CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	6 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Cash Flows From Operating Activities
Net income	$ 743,315	$ 629,531
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization expense	329,695	294,337
Deferred income taxes	110,098	59,060
Other	(28,023)	(27,496)
Net assets / liabilities from risk management activities	1,683	(1,482)
Net change in Winter Storm Uri current regulatory asset	0	2,021,889
Net change in other operating assets and liabilities	(164,895)	(83,123)
Net cash provided by operating activities	991,873	2,892,716
Cash Flows From Investing Activities
Capital expenditures	(1,415,526)	(1,415,349)
Debt and equity securities activities, net	(1,010)	(4,560)
Other, net	7,272	9,519
Net cash used in investing activities	(1,409,264)	(1,410,390)
Cash Flows From Financing Activities
Net decrease in short-term debt	(241,933)	(184,967)
Net proceeds from equity issuances	254,022	359,683
Issuance of common stock through stock purchase and employee retirement plans	7,771	7,910
Proceeds from issuance of long-term debt	898,275	797,258
Proceeds from term loan	0	2,020,000
Repayment of term loan	0	(2,020,000)
Repayment of long-term debt	0	(2,200,000)
Repayment of securitized debt	(5,738)	0
Cash dividends paid	(241,565)	(210,725)
Debt issuance costs	(8,920)	(7,864)
Net cash provided by (used in) financing activities	661,912	(1,438,705)
Net increase in cash and cash equivalents and restricted cash and cash equivalents	244,521	43,621
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	$ 263,769	$ 95,175