Condensed Consolidated Balance Sheets (USD $) In Thousands, unless otherwise specified	Mar. 31, 2012	Sep. 30, 2011	Mar. 31, 2011
Current assets:
Cash and cash equivalents	$ 46,593	$ 7,267	$ 75,472
Restricted cash	4,260	4,308	3,996
Accounts receivable (less allowances for doubtful accounts of $8,900, $6,368 and $13,558, respectively)	105,330	58,736	154,398
Accounts receivable — related parties	6,353	7,048	13,181
Accrued utility revenues	25,474	14,807	43,163
Inventories	23,640	104,263	16,674
Deferred income taxes	33,907	42,528	33,201
Regulatory assets	3,593	8,608	1,762
Derivative financial instruments	185	68	1,920
Prepaid expenses & other current assets	24,000	24,911	19,794
Total current assets	273,335	272,544	363,561
Property, plant and equipment, at cost (less accumulated depreciation and amortization of $800,423, $782,665 and $770,842, respectively)	1,441,612	1,418,356	1,394,053
Goodwill	182,145	182,145	180,145
Regulatory assets	292,096	291,847	254,632
Other assets	4,718	4,456	11,060
Total assets	2,193,906	2,169,348	2,203,451
Current liabilities:
Current maturities of long-term debt	40,000	40,000	0
Accounts payable	27,180	53,556	49,203
Accounts payable — related parties	7,488	10,108	10,742
Deferred fuel refunds	12,022	6,578	33,955
Derivative financial instruments	11,404	11,928	4,291
Other current liabilities	149,357	140,849	163,355
Total current liabilities	247,451	263,019	261,546
Long-term debt	600,000	600,000	640,000
Deferred income taxes	367,088	361,468	305,371
Deferred investment tax credits	4,784	4,958	5,134
Pension and postretirement benefit obligations	130,731	142,248	115,628
Other noncurrent liabilities	81,441	78,810	71,531
Total liabilities	1,431,495	1,450,503	1,399,210
Commitments and contingencies (note 8)
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	468,564	468,323	468,302
Retained earnings	253,631	212,096	279,856
Accumulated other comprehensive loss	(20,043)	(21,833)	(4,176)
Total common stockholder’s equity	762,411	718,845	804,241
Total liabilities and stockholder’s equity	$ 2,193,906	$ 2,169,348	$ 2,203,451