Condensed Consolidated Balance Sheets (USD $) In Thousands, unless otherwise specified	Jun. 30, 2012	Sep. 30, 2011	Jun. 30, 2011
Current assets:
Cash and cash equivalents	$ 75,969	$ 7,267	$ 108,914
Restricted cash	1,604	4,308	4,055
Accounts receivable (less allowances for doubtful accounts of $7,457, $6,368 and $12,927, respectively)	61,072	58,736	87,858
Accounts receivable — related parties	4,311	7,048	4,277
Accrued utility revenues	14,970	14,807	7,417
Inventories	38,413	104,263	58,751
Deferred income taxes	33,595	42,528	32,302
Regulatory assets	2,681	8,608	2,037
Derivative financial instruments	545	68	329
Prepaid expenses & other current assets	17,890	24,911	15,490
Total current assets	251,050	272,544	321,430
Property, plant and equipment, at cost (less accumulated depreciation and amortization of $809,458, $782,665 and $777,773, respectively)	1,458,654	1,418,356	1,393,010
Goodwill	182,145	182,145	180,145
Regulatory assets	288,366	291,847	255,301
Other assets	5,630	4,456	8,678
Total assets	2,185,845	2,169,348	2,158,564
Current liabilities:
Current maturities of long-term debt	40,000	40,000	0
Accounts payable	30,457	53,556	41,487
Accounts payable — related parties	10,175	10,108	9,260
Deferred fuel refunds	10,325	6,578	22,451
Derivative financial instruments	7,150	11,928	5,334
Other current liabilities	144,492	140,849	142,797
Total current liabilities	242,599	263,019	221,329
Long-term debt	600,000	600,000	640,000
Deferred income taxes	371,388	361,468	327,039
Deferred investment tax credits	4,698	4,958	5,046
Pension and postretirement benefit obligations	126,007	142,248	113,235
Other noncurrent liabilities	92,409	78,810	69,898
Total liabilities	1,437,101	1,450,503	1,376,547
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	468,630	468,323	468,323
Retained earnings	246,286	212,096	259,307
Accumulated other comprehensive loss	(26,431)	(21,833)	(5,872)
Total common stockholder’s equity	748,744	718,845	782,017
Total liabilities and stockholder’s equity	$ 2,185,845	$ 2,169,348	$ 2,158,564