Statements of Income (Unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Statements of Income [Abstract]
Operating revenues	$ 12,026	$ 12,254	$ 23,670	$ 23,544
OPERATING EXPENSES:
Operation and maintenance	2,563	2,262	4,917	4,288
Administrative and general	2,254	2,184	4,249	4,272
Depreciation and amortization	1,624	1,686	3,465	3,367
Taxes other than income taxes	267	288	581	621
Operating expenses	6,708	6,420	13,212	12,548
Operating income	5,318	5,834	10,458	10,996
OTHER INCOME (EXPENSES):
Interest on debt	(1,376)	(1,326)	(2,740)	(2,642)
Allowance for funds used during construction	31	196	123	319
Other pension costs	(321)	(305)	(642)	(610)
Other income (expenses), net	(77)	(94)	(159)	(220)
Other income (expenses)	(1,743)	(1,529)	(3,418)	(3,153)
Income before income taxes	3,575	4,305	7,040	7,843
Income taxes	270	1,370	1,141	2,327
Net Income	$ 3,305	$ 2,935	$ 5,899	$ 5,516
Basic Earnings Per Share (in dollars per share)	$ 0.26	$ 0.23	$ 0.46	$ 0.43
Diluted Earnings Per Share (in dollars per share)	0.26	0.23	0.46	0.43
Cash Dividends Declared Per Share (in dollars per share)	$ 0.1666	$ 0.1602	$ 0.3332	$ 0.3204