CONDENSED CONSOLIDATED STATEMENTS OF INCOME - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Income Statement [Abstract]
Operating Revenues	$ 34,919	$ 33,014	$ 66,096	$ 63,145
Operating Expenses:
Operations and Maintenance	16,825	16,856	34,659	32,795
Depreciation	3,736	3,385	7,345	6,693
Other Taxes	3,637	3,415	7,021	6,724
Total Operating Expenses	24,198	23,656	49,025	46,212
Operating Income	10,721	9,358	17,071	16,933
Other Income (Expense):
Allowance for Funds Used During Construction	214	180	381	299
Other Income (Expense), net	571	230	868	436
Total Other Income, net	785	410	1,249	735
Interest Charges	2,068	1,469	3,206	2,472
Income before Income Taxes	9,438	8,299	15,114	15,196
Income Taxes	763	2,918	1,945	5,374
Net Income	8,675	5,381	13,169	9,822
Preferred Stock Dividend Requirements	36	36	72	72
Earnings Applicable to Common Stock	$ 8,639	$ 5,345	$ 13,097	$ 9,750
Earnings per share of Common Stock:
Basic	$ 0.53	$ 0.33	$ 0.80	$ 0.60
Diluted	$ 0.52	$ 0.33	$ 0.80	$ 0.59
Average Number of Common Shares Outstanding:
Basic	16,388	16,332	16,371	16,316
Diluted	16,544	16,488	16,527	16,472
Cash Dividends Paid per Common Share	$ 0.2238	$ 0.2113	$ 0.4475	$ 0.4225