Condensed Consolidated Statements of Cash Flows (unaudited) (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
CASH FLOWS FROM OPERATING ACTIVITIES:
Net income	$ 121,396	$ 95,071
Adjustments to reconcile net income to net cash from operating activities:
Depreciation and amortization	29,093	27,283
Deferred income taxes, net	12,109	4,241
Provision for uncollectible accounts	8,716	6,059
Other, net	414	7,537
Net change in:
Accounts receivable and accrued utility revenues	(173,176)	(136,644)
Inventories	69,032	51,119
Deferred fuel and power costs, net of changes in unsettled derivatives	(10,181)	33,311
Accounts payable	25,726	3,688
Other current assets	1,746	12,632
Other current liabilities	38,355	18,120
Net cash provided by operating activities	123,230	122,417
CASH FLOWS FROM INVESTING ACTIVITIES:
Expenditures for property, plant and equipment	(65,902)	(55,519)
Net costs of property, plant and equipment disposals	(2,948)	(1,437)
Decrease in restricted cash	3,181	0
Net cash used by investing activities	(65,669)	(56,956)
CASH FLOWS FROM FINANCING ACTIVITIES:
Payment of dividends	(37,693)	0
Issuances of long-term debt	175,000	0
Repayments of long-term debt	(175,000)	0
Decrease in bank loans	(11,000)	(9,200)
Other	663	809
Net cash used by financing activities	(48,030)	(8,391)
Cash and cash equivalents increase	9,531	57,070
CASH AND CASH EQUIVALENTS:
End of period	14,238	58,329
Beginning of period	4,707	1,259
Increase	$ 9,531	$ 57,070