CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (Unaudited) - USD ($) $ in Thousands	6 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
CASH FLOWS FROM OPERATING ACTIVITIES
Net income	$ 226,168	$ 207,347
Adjustments to reconcile net income to cash flows from operating activities
Unrealized (gain) on derivative instruments	(17,532)	(40,169)
Depreciation and amortization	74,773	61,828
Amortization of acquired wholesale energy contracts	1,283	1,464
Allowance for equity used during construction	(2,801)	(6,133)
Allowance for doubtful accounts	(395)	1,139
Non cash lease expense	1,848	2,559
Deferred income taxes	36,072	16,912
Equivalent value of ITCs recognized on equipment financing	(899)	(727)
Manufactured gas plant remediation costs	(4,362)	(14,677)
Equity in earnings, net of distributions received from equity investees	0	968
Cost of removal - asset retirement obligations	(644)	(565)
Contributions to postemployment benefit plans	(634)	(2,324)
Taxes related to stock-based compensation	554	(166)
Changes in:
Components of working capital	(42,519)	74,290
Other noncurrent assets	752	4,870
Other noncurrent liabilities	71,457	23,836
Cash flows from operating activities	343,121	330,452
Expenditures for:
Cost of removal	(16,757)	(17,030)
Distribution from equity investees in excess of equity in earnings	1,374	478
Investments in equity investees, net of return of capital	0	4,000
Cash flows used in investing activities	(261,737)	(296,832)
CASH FLOWS USED IN FINANCING ACTIVITIES
Proceeds from long-term debt	175,000	100,000
Payments of long-term debt	(10,534)	(10,032)
Proceeds from term loan	0	150,000
Payments of term loan	(150,000)	0
Payments of short-term debt, net	(86,300)	(225,090)
Proceeds from sale leaseback transactions - solar	61,808	3,300
Proceeds from sale leaseback transactions - natural gas meters	8,441	17,300
Payments of common stock dividends	(75,200)	(63,725)
Proceeds from waiver discount issuance of common stock	17,919	0
Proceeds from issuance of common stock - DRP	7,610	7,521
Tax withholding payments related to net settled stock compensation	(4,024)	(3,737)
Cash flows used in financing activities	(55,280)	(24,463)
Change in cash, cash equivalents and restricted cash	26,104	9,157
Cash, cash equivalents and restricted cash at beginning of period	1,452	6,043
Cash, cash equivalents and restricted cash at end of period	27,556	15,200
CHANGES IN COMPONENTS OF WORKING CAPITAL
Receivables	(8,877)	(107,479)
Inventories	185,444	125,012
Recovery of natural gas costs	(28,825)	8,465
Natural gas purchases payable	(159,016)	(25,964)
Natural gas purchases payable - related parties	5	(6)
Deferred revenue, current	1,587	52,368
Accounts payable and other	(24,095)	(88,866)
Prepaid expenses	(6,493)	(5,548)
Prepaid and accrued taxes	51,591	75,921
Restricted broker margin accounts	(43,414)	53,708
Customers' credit balances and deposits	(7,725)	(12,302)
Other current assets (liabilities)	(2,701)	(1,019)
Total	(42,519)	74,290
Cash paid for:
Interest (net of amounts capitalized)	57,622	42,754
Income taxes	1,967	1,263
Accrued capital expenditures	24,318	53,245
Utility plant
Expenditures for:
Payments to acquire PP&E	(157,914)	(108,434)
Solar equipment
Expenditures for:
Payments to acquire PP&E	(57,699)	(66,556)
Storage and Transportation and other
Expenditures for:
Payments to acquire PP&E	$ (30,741)	$ (109,290)