CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
CASH FLOWS USED IN OPERATING ACTIVITIES
Net income	$ 115,921	$ 111,312
Adjustments to reconcile net income to cash flows from operating activities
Unrealized (gain) on derivative instruments	(31,503)	(82,191)
Depreciation and amortization	36,683	30,393
Amortization of acquired wholesale energy contracts	530	589
Allowance for equity used during construction	(1,054)	(2,494)
Allowance for doubtful accounts	(2,459)	550
Non cash lease expense	727	889
Deferred income taxes	11,861	14,855
Equivalent value of ITCs recognized on equipment financing	(899)	(727)
Manufactured gas plant remediation costs	(2,627)	(12,368)
Equity in earnings, net of distributions received from equity investees	0	481
Cost of removal - asset retirement obligations	(322)	(282)
Contributions to postemployment benefit plans	(249)	(1,942)
Taxes related to stock-based compensation	554	(166)
Changes in:
Components of working capital	(335,025)	(153,195)
Other noncurrent assets	4,440	(1,529)
Other noncurrent liabilities	114,475	58,418
Cash flows used in operating activities	(88,947)	(37,407)
Expenditures for:
Cost of removal	(7,329)	(9,114)
Distribution from equity investees in excess of equity in earnings	361	244
Cash flows used in investing activities	(145,562)	(164,054)
CASH FLOWS FROM FINANCING ACTIVITIES
Proceeds from long-term debt	175,000	100,000
Payments of long-term debt	(4,782)	(1,810)
Proceeds from short-term debt, net	40,500	110,650
Proceeds from sale leaseback transactions - solar	33,150	3,300
Proceeds from sale leaseback transactions - natural gas meters	8,441	17,300
Payments of common stock dividends	(34,508)	(31,841)
Proceeds from waiver discount issuance of common stock	17,919	0
Proceeds from issuance of common stock - DRP	3,847	3,805
Tax withholding payments related to net settled stock compensation	(3,642)	(3,433)
Cash flows from financing activities	235,925	197,971
Change in cash, cash equivalents and restricted cash	1,416	(3,490)
Cash, cash equivalents and restricted cash at beginning of period	1,452	6,043
Cash, cash equivalents and restricted cash at end of period	2,868	2,553
CHANGES IN COMPONENTS OF WORKING CAPITAL
Receivables	(247,080)	(117,010)
Inventories	17,974	(48,866)
Recovery of natural gas costs	27,904	(4,505)
Natural gas purchases payable	(76,930)	(18,752)
Natural gas purchases payable - related parties	11	(10)
Deferred revenue, current	0	51,107
Accounts payable and other	(35,361)	(44,374)
Prepaid expenses	(10,456)	(6,951)
Prepaid and accrued taxes	39,301	31,205
Restricted broker margin accounts	(56,460)	(459)
Customers' credit balances and deposits	7,724	6,080
Other current assets (liabilities)	(1,652)	(660)
Total	(335,025)	(153,195)
Cash paid for:
Interest (net of amounts capitalized)	22,986	13,935
Income taxes	30	(229)
Accrued capital expenditures	24,119	57,129
Utility plant
Expenditures for:
Payments to acquire PP&E	(74,742)	(64,350)
Solar equipment
Expenditures for:
Payments to acquire PP&E	(43,993)	(25,380)
Storage and Transportation and other
Expenditures for:
Payments to acquire PP&E	$ (19,859)	$ (65,454)