Condensed Consolidated Balance Sheets (unaudited) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Sep. 30, 2012	Mar. 31, 2012
Current assets:
Cash and cash equivalents	$ 58,329	$ 1,259	$ 46,593
Restricted cash	0	0	4,260
Accounts receivable (less allowances for doubtful accounts of $8,052, $3,588 and $8,900, respectively)	141,053	47,362	105,330
Accounts receivable — related parties	9,518	4,571	6,353
Accrued utility revenues	48,857	16,911	25,474
Inventories	16,215	67,334	23,640
Deferred income taxes	53,515	46,436	33,907
Regulatory assets	1,072	6,473	3,593
Derivative financial instruments	8,528	5,468	185
Prepaid expenses & other current assets	16,755	29,313	24,000
Total current assets	353,842	225,127	273,335
Property, plant and equipment, at cost (less accumulated depreciation and amortization of $837,110, $815,720 and $800,423, respectively)	1,508,985	1,479,949	1,441,612
Goodwill	182,145	182,145	182,145
Regulatory assets	321,257	331,932	292,096
Other assets	2,808	4,026	4,718
Total assets	2,369,037	2,223,179	2,193,906
Current liabilities:
Current maturities of long-term debt	133,000	133,000	40,000
Bank loans	0	9,200	0
Accounts payable	48,099	46,754	27,180
Accounts payable — related parties	12,535	10,192	7,488
Deferred fuel refunds	31,209	4,435	12,022
Derivative financial instruments	29,077	36,011	11,404
Other current liabilities	149,801	131,092	149,357
Total current liabilities	403,721	370,684	247,451
Long-term debt	467,000	467,000	600,000
Deferred income taxes	433,868	417,052	367,088
Deferred investment tax credits	4,440	4,612	4,784
Pension and postretirement benefit obligations	174,905	179,056	130,731
Other noncurrent liabilities	53,965	56,262	81,441
Total liabilities	1,537,899	1,494,666	1,431,495
Commitments and contingencies (note 8)
Common stockholder’s equity:
Common Stock, $2.25 par value (authorized — 40,000,000 shares; issued and outstanding — 26,781,785 shares)	60,259	60,259	60,259
Additional paid-in capital	469,501	468,692	468,564
Retained earnings	324,450	229,379	253,631
Accumulated other comprehensive loss	(23,072)	(29,817)	(20,043)
Total common stockholder’s equity	831,138	728,513	762,411
Total liabilities and stockholder’s equity	$ 2,369,037	$ 2,223,179	$ 2,193,906