Condensed Consolidated Balance Sheets (unaudited) - USD ($) $ in Thousands	Dec. 31, 2015	Sep. 30, 2015	Dec. 31, 2014
Current assets:
Cash and cash equivalents	$ 15,585	$ 3,099	$ 14,267
Restricted cash	6,324	6,602	8,963
Accounts receivable (less allowances for doubtful accounts of $5,283, $5,599 and $6,764, respectively)	78,954	55,659	116,454
Accounts receivable — related parties	2,671	1,271	2,901
Accrued utility revenues	30,776	12,051	52,743
Inventories	49,365	51,716	85,429
Deferred income taxes	0	24,694	1,600
Income taxes receivable	31,465	10,026	0
Regulatory assets	3,905	4,105	16,773
Derivative instruments	234	934	0
Prepaid expenses & other current assets	28,670	23,903	19,052
Total current assets	247,949	194,060	318,182
Property, plant and equipment, at cost (less accumulated depreciation and amortization of $940,655, $929,130 and $897,802, respectively)	1,870,732	1,824,369	1,727,117
Goodwill	182,145	182,145	182,145
Regulatory assets	297,914	300,103	253,826
Other assets	7,559	7,501	7,351
Total assets	2,606,299	2,508,178	2,488,621
Current liabilities:
Current maturities of long-term debt	175,000	247,000	92,000
Short-term borrowings	217,700	71,700	153,500
Accounts payable	51,954	58,135	65,574
Accounts payable — related parties	7,069	4,430	10,716
Regulatory liability — deferred fuel refunds	28,083	36,638	0
Derivative instruments	10,351	12,591	9,434
Other current liabilities	112,528	103,265	123,285
Total current liabilities	602,685	533,759	454,509
Long-term debt	375,000	375,000	550,000
Deferred income taxes	524,287	512,497	466,037
Deferred investment tax credits	3,513	3,597	3,849
Pension and postretirement benefit obligations	132,899	135,003	96,861
Derivative instruments	0	0	344
Other noncurrent liabilities	58,469	57,702	53,418
Total liabilities	$ 1,696,853	$ 1,617,558	$ 1,625,018
Commitments and contingencies
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	471,952	471,904	471,076
Retained earnings	388,494	372,143	339,927
Accumulated other comprehensive loss	(11,259)	(13,686)	(7,659)
Total common stockholder’s equity	909,446	890,620	863,603
Total liabilities and stockholder’s equity	$ 2,606,299	$ 2,508,178	$ 2,488,621