CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Jun. 30, 2023	Jun. 30, 2022
CASH FLOWS FROM OPERATING ACTIVITIES
Net income	$ 227,700	$ 220,400
Adjustments to reconcile net income to cash flows from operating activities
Unrealized (gain) on derivative instruments	(30,502)	(58,060)
Depreciation and amortization	113,650	94,700
Amortization of acquired wholesale energy contracts	1,781	2,016
Allowance for equity used during construction	(5,054)	(9,197)
Allowance for doubtful accounts	1,397	1,768
Non cash lease expense	2,607	3,720
Deferred income taxes	11,026	37,547
Equivalent value of ITCs recognized on equipment financing	(1,232)	(1,060)
Manufactured gas plant remediation costs	(6,284)	(16,341)
Cost of removal - asset retirement obligations	(967)	(847)
Contributions to postemployment benefit plans	(1,133)	(2,702)
Taxes related to stock-based compensation	554	(164)
Changes in:
Components of working capital	22,229	(97,572)
Other noncurrent assets	(16,207)	(7,639)
Other noncurrent liabilities	68,333	69,308
Cash flows from operating activities	387,898	235,877
Expenditures for:
Cost of removal	(28,719)	(27,881)
Distribution from equity investees in excess of equity in earnings	2,036	690
Investments in equity investees, net of return of capital	0	5,479
Cash flows used in investing activities	(378,178)	(434,945)
CASH FLOWS (USED IN) FROM FINANCING ACTIVITIES
Proceeds from long-term debt	175,000	310,000
Payments of long-term debt	(15,698)	(14,223)
Proceeds from term loan	0	150,000
Payments of term loan	(150,000)	0
Payments of short-term debt, net	(128,725)	(156,950)
Proceeds from sale leaseback transactions - solar	163,619	3,300
Proceeds from sale leaseback transactions - natural gas meters	8,441	17,300
Payments of common stock dividends	(112,991)	(95,691)
Proceeds from waiver discount issuance of common stock	42,807	0
Proceeds from issuance of common stock - DRP	11,419	11,076
Tax withholding payments related to net settled stock compensation	(4,024)	(3,794)
Cash flows (used in) from financing activities	(10,152)	221,018
Change in cash, cash equivalents and restricted cash	(432)	21,950
Cash, cash equivalents and restricted cash at beginning of period	1,452	6,043
Cash, cash equivalents and restricted cash at end of period	1,020	27,993
CHANGES IN COMPONENTS OF WORKING CAPITAL
Receivables	103,954	(61,836)
Inventories	108,107	(12,672)
Recovery of natural gas costs	(20,106)	3,772
Natural gas purchases payable	(188,617)	33,362
Natural gas purchases payable - related parties	5	(6)
Deferred revenue, current	2,687	44,304
Accounts payable and other	(20,153)	(70,194)
Prepaid expenses	(2,454)	(1,219)
Prepaid and accrued taxes	24,684	18,770
Restricted broker margin accounts	22,868	(47,643)
Customers' credit balances and deposits	(2,979)	(10,370)
Other current assets (liabilities)	(5,767)	6,160
Total	22,229	(97,572)
Cash paid for:
Interest (net of amounts capitalized)	80,550	65,385
Income taxes	2,858	3,763
Accrued capital expenditures	21,008	40,833
Utility plant
Expenditures for:
Payments to acquire PP&E	(248,507)	(177,559)
Solar equipment
Expenditures for:
Payments to acquire PP&E	(68,604)	(105,504)
Storage and Transportation and other
Expenditures for:
Payments to acquire PP&E	$ (34,384)	$ (130,170)