Condensed Consolidated Balance Sheets (unaudited) - USD ($) $ in Thousands	Jun. 30, 2017	Sep. 30, 2016	Jun. 30, 2016
Current assets:
Cash and cash equivalents	$ 4,828	$ 2,819	$ 82,449
Restricted cash	2,524	583	212
Accounts receivable (less allowances for doubtful accounts of $10,050, $3,946 and $7,921, respectively)	69,246	44,692	59,301
Accounts receivable — related parties	718	398	638
Accrued utility revenues	5,924	12,753	10,099
Inventories	37,129	42,340	27,009
Prepaid income taxes	428	1,956	0
Regulatory assets	7,759	3,208	3,263
Derivative instruments	942	4,263	5,384
Prepaid expenses & other current assets	12,995	22,009	33,724
Total current assets	142,493	135,021	222,079
Property, plant and equipment, at cost (less accumulated depreciation and amortization of $1,008,121, $975,374 and $961,006, respectively)	2,174,609	2,023,541	1,945,539
Goodwill	182,145	182,145	182,145
Regulatory assets	390,988	391,933	342,037
Other assets	14,297	10,451	5,501
Total assets	2,904,532	2,743,091	2,697,301
Current liabilities:
Current maturities of long-term debt	39,990	19,986	19,981
Short-term borrowings	50,000	112,500	130,000
Accounts payable	56,866	65,180	50,665
Accounts payable — related parties	7,625	3,995	5,838
Regulatory liability — deferred fuel and power refunds	12,587	22,299	34,432
Derivative instruments	1,056	310	507
Other current liabilities	129,325	109,640	113,011
Total current liabilities	297,449	333,910	354,434
Long-term debt	711,116	651,455	627,422
Deferred income taxes	614,419	550,229	545,614
Deferred investment tax credits	3,029	3,268	3,348
Pension and postretirement benefit obligations	176,393	184,516	128,932
Other noncurrent liabilities	95,108	94,976	98,652
Total liabilities	1,897,514	1,818,354	1,758,402
Commitments and contingencies (Note 7)
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	473,580	473,580	473,295
Retained earnings	502,603	422,516	434,391
Accumulated other comprehensive loss	(29,424)	(31,618)	(29,046)
Total common stockholder’s equity	1,007,018	924,737	938,899
Total liabilities and stockholder’s equity	$ 2,904,532	$ 2,743,091	$ 2,697,301