CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Dec. 31, 2024	Dec. 31, 2023
CASH FLOWS (USED IN) FROM OPERATING ACTIVITIES
Net income	$ 131,319	$ 89,411
Adjustments to reconcile net income to cash flows from operating activities
Unrealized loss (gain) on derivative instruments	6,368	(5,400)
Gain on sale of assets	(54,859)	0
Depreciation and amortization	45,329	40,287
Amortization of acquired wholesale energy contracts	0	111
Allowance for equity used during construction	(1,086)	(1,482)
Allowance for doubtful accounts	194	(1,575)
Non cash lease expense	1,071	1,152
Deferred income taxes	20,522	18,758
Equivalent value of ITCs recognized on equipment financing	(4,352)	(2,888)
Manufactured gas plant remediation costs	(1,126)	(4,575)
Cost of removal - asset retirement obligations	(432)	(382)
Contributions to postemployment benefit plans	(227)	(1,996)
Taxes related to stock-based compensation	1,805	1,185
Changes in:
Components of working capital	(187,879)	(97,615)
Other noncurrent assets and liabilities	34,398	11,424
Cash flows (used in) from operating activities	(8,955)	46,415
Expenditures for:
Cost of removal	(10,775)	(8,977)
Distribution from equity investees in excess of equity in earnings	99	830
Proceeds from sale of assets	132,500	0
Cash flows used in investing activities	(19,271)	(113,792)
CASH FLOWS FROM FINANCING ACTIVITIES
Proceeds from long-term debt	100,000	50,000
Payments of long-term debt	(107,676)	(6,188)
Proceeds from short-term debt, net	45,200	16,550
Proceeds from sale leaseback transactions - solar	12,567	24,394
Proceeds from sale leaseback transactions - natural gas meters	11,714	8,814
Payments of common stock dividends	(44,752)	(40,981)
Proceeds from waiver discount issuance of common stock	19,910	17,919
Proceeds from issuance of common stock - DRP	3,793	3,781
Tax withholding payments related to net settled stock compensation	(11,579)	(5,000)
Cash flows from financing activities	29,177	69,289
Change in cash, cash equivalents and restricted cash	951	1,912
Cash, cash equivalents and restricted cash at beginning of period	1,612	1,517
Cash, cash equivalents and restricted cash at end of period	2,563	3,429
CHANGES IN COMPONENTS OF WORKING CAPITAL
Receivables	(203,094)	(146,377)
Inventories	5,247	1,948
Recovery of natural gas costs	(375)	479
Natural gas purchases payable	30,998	24,901
Natural gas purchases payable - related parties	6	(2)
Deferred revenue, current	650	57,115
Accounts payable and other	(45,967)	(47,797)
Prepaid expenses	(7,421)	(5,794)
Prepaid and accrued taxes	35,204	20,895
Restricted broker margin accounts	(2,849)	(837)
Customers' credit balances and deposits	3,992	551
Other current assets and liabilities	(4,270)	(2,697)
Total	(187,879)	(97,615)
Cash paid for:
Interest (net of amounts capitalized)	34,843	29,779
Income taxes	863	629
Accrued capital expenditures	19,309	13,333
Utility plant
Expenditures for:
Payments to acquire PP&E	(99,143)	(71,166)
Solar equipment
Expenditures for:
Payments to acquire PP&E	(33,476)	(25,766)
Storage and Transportation and other
Expenditures for:
Payments to acquire PP&E	$ (8,476)	$ (8,713)