Condensed Consolidated Statements of Cash Flows (unaudited) - USD ($) $ in Thousands	6 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
CASH FLOWS FROM OPERATING ACTIVITIES
Net income	$ 157,487	$ 109,390
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	41,512	35,090
Deferred income tax (benefit) expense	(1,619)	35,992
Provision for uncollectible accounts	13,142	6,265
Other, net	(345)	6,292
Net change in:
Accounts receivable and accrued utility revenues	(176,795)	(110,111)
Inventories	33,592	25,166
Deferred fuel and power costs, net of changes in unsettled derivatives	31,481	(7,601)
Accounts payable	17,302	14,722
Other current assets	(3,791)	(948)
Other current liabilities	23,090	17,591
Net cash provided by operating activities	135,056	131,848
CASH FLOWS FROM INVESTING ACTIVITIES
Expenditures for property, plant and equipment	(151,468)	(135,075)
Net costs of property, plant and equipment disposals	(3,397)	(5,753)
Decrease in restricted cash	1,474	236
Net cash used by investing activities	(153,391)	(140,592)
CASH FLOWS FROM FINANCING ACTIVITIES
Payments of dividends	(30,000)	(25,000)
Issuances of long-term debt, net of issuance costs	124,404	99,491
Repayments of long-term debt	(41,562)	0
Decrease in short-term borrowings	(35,000)	(64,000)
Net cash provided by financing activities	17,842	10,491
Cash and cash equivalents (decrease) increase	(493)	1,747
CASH AND CASH EQUIVALENTS
End of period	4,710	4,566
Beginning of period	5,203	2,819
(Decrease) increase	$ (493)	$ 1,747