CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
CASH FLOWS USED IN OPERATING ACTIVITIES
Net income	$ 89,361	$ 86,248
Adjustments to reconcile net income to cash flows from operating activities
Unrealized gain on derivative instruments	(41,766)	(10,932)
Realized and unrealized gains on investments in equity securities	0	(257)
Depreciation and amortization	27,758	21,832
Amortization of acquired wholesale energy contracts	134	370
Allowance for equity used during construction	(2,732)	(1,751)
Allowance for doubtful accounts	430	643
Non cash lease expense	861
Deferred income taxes	3,246	(8,733)
Manufactured gas plant remediation costs	(2,974)	(2,593)
Equity in earnings, net of distributions received from equity investees	(1,332)	(830)
Cost of removal - asset retirement obligations	(61)	(65)
Contributions to postemployment benefit plans	(2,256)	(1,666)
Tax benefit from stock-based compensation	798	1,279
Changes in:
Components of working capital	(117,241)	(206,728)
Other noncurrent assets	1,312	9,710
Other noncurrent liabilities	1,398	8,718
Cash flows used in operating activities	(43,064)	(104,755)
Expenditures for:
Cost of removal	(7,936)	(8,396)
Acquisition of assets, net of cash acquired of $5.1 million	(368,126)	0
Distribution from equity investees in excess of equity in earnings	643	619
Investments in equity investees	(509)	0
Cash flows used in investing activities	(494,175)	(93,682)
CASH FLOWS FROM FINANCING ACTIVITIES
Proceeds from term loan	350,000	0
Payments of term loan	(212,900)	0
Payments of long-term debt	(3,853)	(4,723)
Proceeds from short-term debt, net	228,159	219,750
Proceeds from sale-leaseback transaction	4,000
Proceeds from sale-leaseback transaction		9,895
Payments of common stock dividends	(26,974)	(25,812)
Proceeds from issuance of common stock - public equity offering	212,900	0
Proceeds from waiver discount issuance of common stock	0	7,964
Proceeds from issuance of common stock - DRP	3,572	3,749
Tax withholding payments related to net settled stock compensation	(3,543)	(6,087)
Cash flows from financing activities	551,361	204,736
Change in cash, cash equivalents and restricted cash	14,122	6,299
Cash, cash equivalents and restricted cash at beginning of period	4,063	1,710
Cash, cash equivalents and restricted cash at end of period	18,185	8,009
CHANGES IN COMPONENTS OF WORKING CAPITAL
Receivables	(164,622)	(161,039)
Inventories	(17,055)	(58,061)
Recovery of gas costs	7,951	(1,142)
Gas purchases payable	44,086	58,663
Prepaid expenses	(12,482)	4,048
Prepaid and accrued taxes	15,390	17,027
Accounts payable and other	(27,080)	(47,498)
Restricted broker margin accounts	34,976	(9,963)
Customers' credit balances and deposits	2,457	2,304
Other current assets	(862)	(11,067)
Cash paid for:
Interest (net of amounts capitalized)	14,938	16,002
Income taxes	0	130
Accrued capital expenditures	14,864	19,791
Utility Plant
Expenditures for:
Payments to acquire PP&E	(69,861)	(51,359)
Solar Equipment
Expenditures for:
Payments to acquire PP&E	(45,699)	(32,126)
Midstream and Other Property
Expenditures for:
Payments to acquire PP&E	$ (2,687)	$ (2,420)