CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (Unaudited) - USD ($) $ in Thousands	6 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
CASH FLOWS USED IN OPERATING ACTIVITIES
Net income	$ 177,866	$ 159,821
Adjustments to reconcile net income to cash flows from operating activities
Unrealized gain on derivative instruments	(45,539)	(707)
Realized and unrealized gains on investments in equity securities	0	(1,567)
Gain on sale of businesses	0	(645)
Depreciation and amortization	58,542	44,143
Amortization of acquired wholesale energy contracts	3,953	7,346
Allowance for equity used during construction	(8,053)	(3,602)
Allowance for doubtful accounts	951	1,149
Non cash lease expense	1,856
Deferred income taxes	318	16,337
Manufactured gas plant remediation costs	(5,291)	(4,353)
Equity in earnings, net of distributions received from equity investees	(2,760)	(1,836)
Cost of removal - asset retirement obligations	(122)	(130)
Contributions to postemployment benefit plans	(5,742)	(1,909)
Tax benefit from stock-based compensation	803	1,284
Changes in:
Components of working capital	3,526	(71,746)
Other noncurrent assets	(1,258)	13,483
Other noncurrent liabilities	95	14,719
Cash flows from operating activities	179,145	171,787
Expenditures for:
Cost of removal	(17,487)	(17,134)
Acquisition of assets, net of cash acquired of $5.1 million	(523,647)	0
Distribution from equity investees in excess of equity in earnings	1,132	1,154
Investments in equity investees	(1,266)	(1,457)
Proceeds from sale of businesses, net of closing costs	0	205,745
Proceeds from sale of investments in equity securities, net	0	34,484
Cash flows (used in) from investing activities	(751,130)	42,524
CASH FLOWS FROM (USED IN) FINANCING ACTIVITIES
Proceeds from term loan	350,000	0
Payments of term loan	(212,900)	0
Payments of long-term debt	(9,764)	(12,005)
Proceeds from (payments of) short-term debt, net	304,023	(106,050)
Proceeds from sale-leaseback transaction	4,000
Proceeds from sale-leaseback transaction		9,895
Payments of common stock dividends	(56,821)	(51,750)
Proceeds from issuance of common stock - public equity offering	212,900	0
Proceeds from waiver discount issuance of common stock	0	24,539
Proceeds from issuance of common stock - DRP	8,767	9,522
Tax withholding payments related to net settled stock compensation	(3,893)	(6,607)
Cash flows from (used in) financing activities	596,312	(132,456)
Change in cash, cash equivalents and restricted cash	24,327	81,855
Cash, cash equivalents and restricted cash at beginning of period	4,063	1,710
Cash, cash equivalents and restricted cash at end of period	28,390	83,565
CHANGES IN COMPONENTS OF WORKING CAPITAL
Receivables	(87,532)	(105,900)
Inventories	90,484	125,810
Recovery of gas costs	(21,891)	(14,989)
Gas purchases payable	(10,922)	(21,544)
Prepaid expenses	(602)	(4,162)
Prepaid and accrued taxes	22,258	(4,555)
Accounts payable and other	(27,345)	(35,953)
Restricted broker margin accounts	39,193	(2,217)
Customers' credit balances and deposits	(7,788)	(9,163)
Other current assets	7,671	927
Components of working capital	3,526	(71,746)
Cash paid for:
Interest (net of amounts capitalized)	32,872	27,454
Income taxes	1,193	1,003
Accrued capital expenditures	17,930	29,685
Utility Plant
Expenditures for:
Payments to acquire PP&E	(132,352)	(121,962)
Solar Equipment
Expenditures for:
Payments to acquire PP&E	(69,786)	(52,520)
Midstream and Other Property
Expenditures for:
Payments to acquire PP&E	$ (7,724)	$ (5,786)