CONDENSED CONSOLIDATED STATEMENTS OF INCOME - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Income Statement [Abstract]
Operating Revenues	$ 33,014	$ 32,725	$ 63,145	$ 63,304
Operating Expenses:
Operations and Maintenance	16,651	15,789	32,385	31,617
Depreciation	3,385	3,180	6,693	6,317
Other Taxes	3,415	3,428	6,724	6,740
Total Operating Expenses	23,451	22,397	45,802	44,674
Operating Income	9,563	10,328	17,343	18,630
Other Income (Expense):
Allowance for Funds Used During Construction	180	119	299	180
Other Income	47	25	53	73
Other Expense	(22)	(7)	(27)	(26)
Total Other Income, net	205	137	325	227
Interest Charges	1,469	1,436	2,472	2,413
Income before Income Taxes	8,299	9,029	15,196	16,444
Income Taxes	2,918	3,110	5,374	5,735
Net Income	5,381	5,919	9,822	10,709
Preferred Stock Dividend Requirements	36	36	72	72
Earnings Applicable to Common Stock	$ 5,345	$ 5,883	$ 9,750	$ 10,637
Earnings per share of Common Stock:
Basic	$ 0.33	$ 0.36	$ 0.60	$ 0.65
Diluted	$ 0.33	$ 0.36	$ 0.59	$ 0.65
Average Number of Common Shares Outstanding:
Basic	16,332	16,271	16,316	16,252
Diluted	16,488	16,427	16,472	16,408
Cash Dividends Paid per Common Share	$ 0.2113	$ 0.1988	$ 0.4225	$ 0.3975