Condensed Consolidated Balance Sheets (unaudited) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Sep. 30, 2014	Dec. 31, 2013
Current assets:
Cash and cash equivalents	$ 14,267	$ 12,401	$ 13,008
Restricted cash	8,963	3,592	0
Accounts receivable (less allowances for doubtful accounts of $6,764, $6,992 and $5,885, respectively)	116,454	65,080	111,840
Accounts receivable — related parties	2,901	2,865	9,431
Accrued utility revenues	52,743	14,330	66,370
Inventories	85,429	95,219	80,675
Deferred income taxes	1,600	1,492	12,317
Regulatory assets	16,773	13,159	361
Derivative instruments	0	1,028	2,058
Prepaid expenses & other current assets	19,052	18,535	14,649
Total current assets	318,182	227,701	310,709
Property, plant and equipment, at cost (less accumulated depreciation and amortization of $897,802, $886,268 and $865,852, respectively)	1,727,117	1,682,284	1,594,554
Goodwill	182,145	182,145	182,145
Regulatory assets	253,826	255,007	233,636
Other assets	7,351	7,506	5,626
Total assets	2,488,621	2,354,643	2,326,670
Current liabilities:
Current maturities of long-term debt	92,000	20,000	0
Short-term borrowings	153,500	86,300	73,500
Accounts payable	65,574	58,453	60,405
Accounts payable — related parties	10,716	11,761	17,250
Derivative instruments	9,434	1,632	3,272
Other current liabilities	123,285	99,336	139,037
Total current liabilities	454,509	277,482	293,464
Long-term debt	550,000	622,000	642,000
Deferred income taxes	466,037	461,461	440,645
Deferred investment tax credits	3,849	3,933	4,185
Pension and postretirement benefit obligations	96,861	98,363	73,132
Derivative instruments	344	0	0
Other noncurrent liabilities	53,418	51,567	53,610
Total liabilities	1,625,018	1,514,806	1,507,036
Commitments and contingencies (Note 6)
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	471,076	471,071	470,189
Retained earnings	339,927	316,688	297,417
Accumulated other comprehensive loss	(7,659)	(8,181)	(8,231)
Total common stockholder’s equity	863,603	839,837	819,634
Total liabilities and stockholder’s equity	$ 2,488,621	$ 2,354,643	$ 2,326,670