Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2014
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income	$ 97,373	$ 121,055	$ 124,106
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	67,303	63,590	59,219
Deferred income taxes, net	76,938	29,356	33,588
Pension contributions, net of pension expense	1,580	(1,415)	(9,459)
Settlement of interest rate protection agreements	(35,975)	0	0
Provision for uncollectible accounts	7,760	13,498	13,149
Other, net	(10,112)	3,228	3,998
Net change in:
Accounts receivable and accrued utility revenues	1,120	7,297	(19,718)
Inventories	9,376	43,503	(5,558)
Deferred fuel costs, net of changes in unsettled derivatives	(22,740)	51,778	(17,632)
Accounts payable	(3,053)	(7,649)	5,757
Other current assets	(70)	(9,723)	362
Other current liabilities	15,870	(7,808)	864
Net cash provided by operating activities	205,370	306,710	188,676
CASH FLOWS FROM INVESTING ACTIVITIES:
Expenditures for property, plant and equipment	(250,584)	(203,192)	(164,180)
Net costs of property, plant and equipment disposals	(7,940)	(10,443)	(8,214)
Decrease (increase) in restricted cash	6,019	(3,010)	(411)
Net cash used by investing activities	(252,505)	(216,645)	(172,805)
CASH FLOWS FROM FINANCING ACTIVITIES:
Payment of dividends	(47,000)	(65,600)	(77,395)
Increase (decrease) in short-term borrowings	40,800	(14,600)	68,800
Issuances of long-term debt, net of issuance costs	298,379	0	174,445
Repayments of long-term debt	(247,000)	(20,000)	(175,000)
Excess tax benefits from equity-based payment arrangements	1,676	833	973
Net cash provided (used) by financing activities	46,855	(99,367)	(8,177)
Cash and cash equivalents (decrease) increase	(280)	(9,302)	7,694
CASH AND CASH EQUIVALENTS:
End of year	2,819	3,099	12,401
Beginning of year	3,099	12,401	4,707
(Decrease) increase	(280)	(9,302)	7,694
Cash paid (received) for:
Interest	36,155	38,405	34,781
Income taxes	$ (19,758)	$ 54,427	$ 54,293