Condensed Consolidated Balance Sheets (unaudited) - USD ($) $ in Thousands	Jun. 30, 2018	Sep. 30, 2017	Jun. 30, 2017
Current assets:
Cash and cash equivalents	$ 23,181	$ 5,203	$ 4,828
Restricted cash	805	3,046	2,524
Accounts receivable (less allowances for doubtful accounts of $16,261, $4,052 and $10,050, respectively)	107,966	53,720	69,246
Accounts receivable — related parties	1,682	2,807	718
Accrued utility revenues	14,425	13,296	5,924
Inventories	34,663	53,309	37,129
Prepaid income taxes	41	7,711	428
Regulatory assets	2,180	8,338	7,759
Derivative instruments	1,874	1,354	942
Prepaid expenses & other current assets	19,056	16,406	12,995
Total current assets	205,873	165,190	142,493
Property, plant and equipment, at cost (less accumulated depreciation and amortization of $1,069,070, $1,010,781 and $1,008,121, respectively)	2,430,893	2,274,548	2,174,609
Goodwill	182,145	182,145	182,145
Regulatory assets	357,881	360,591	390,988
Other assets	17,233	11,541	14,297
Total assets	3,194,025	2,994,015	2,904,532
Current liabilities:
Current maturities of long-term debt	9,474	39,996	39,990
Short-term borrowings	118,500	170,000	50,000
Accounts payable	56,297	71,559	56,866
Accounts payable — related parties	14,385	6,890	7,625
Regulatory liabilities	49,664	12,988	15,294
Derivative instruments	0	1,071	1,056
Other current liabilities	119,196	110,978	126,618
Total current liabilities	367,516	413,482	297,449
Long-term debt	830,982	711,105	711,116
Deferred income taxes	336,035	635,465	614,419
Deferred investment tax credits	2,711	2,950	3,029
Pension and postretirement benefit obligations	133,235	143,674	176,393
Regulatory liabilities, Noncurrent	362,787	36,242	33,376
Other noncurrent liabilities	60,954	63,192	61,732
Total liabilities	2,094,220	2,006,110	1,897,514
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	473,580	473,580	473,580
Retained earnings	590,321	480,857	502,603
Accumulated other comprehensive loss	(24,355)	(26,791)	(29,424)
Total common stockholder’s equity	1,099,805	987,905	1,007,018
Total liabilities and stockholder’s equity	$ 3,194,025	$ 2,994,015	$ 2,904,532