CONDENSED CONSOLIDATED STATEMENTS OF INCOME - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Income Statement [Abstract]
Operating Revenues	$ 36,174	$ 37,794	$ 99,319	$ 101,098
Operating Expenses:
Operations and Maintenance	16,178	16,599	48,563	48,215
Depreciation	3,587	3,243	10,280	9,561
Other Taxes	3,603	3,796	10,327	10,537
Total Operating Expenses	23,368	23,638	69,170	68,313
Operating Income	12,806	14,156	30,149	32,785
Other Income (Expense):
Allowance for Funds Used During Construction	174	207	473	387
Other Income	43	400	69	449
Total Other Income, net	217	607	542	836
Interest Charges	1,493	1,427	3,965	3,841
Income before Income Taxes	11,530	13,336	26,726	29,780
Income Taxes	3,888	4,523	9,263	10,258
Net Income	7,642	8,813	17,463	19,522
Preferred Stock Dividend Requirements	36	36	108	108
Earnings Applicable to Common Stock	$ 7,606	$ 8,777	$ 17,355	$ 19,414
Earnings per share of Common Stock:
Basic	$ 0.47	$ 0.54	$ 1.06	$ 1.19
Diluted	$ 0.46	$ 0.54	$ 1.06	$ 1.19
Average Number of Common Shares Outstanding:
Basic	16,340	16,284	16,324	16,262
Diluted	16,496	16,440	16,480	16,418
Cash Dividends Paid per Common Share	$ 0.2113	$ 0.1988	$ 0.6338	$ 0.5963