Business Segment Data (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014 N	Jun. 30, 2013	Dec. 31, 2013
Segment Reporting Information [Line Items]
Number of Reportable Segments			2
Operating Revenues	$ 29,190	$ 29,102	$ 56,363	$ 56,140
Operating Income	8,747	8,171	14,714	14,036
Net Income	4,728	4,481	7,897	7,658
Capital Expenditures	4,339	5,716	8,505	10,222
Assets	538,614		538,614		530,341
Regulated [Member]
Segment Reporting Information [Line Items]
Operating Revenues	25,720	25,637	49,373	49,061
Operating Income	8,143	7,678	13,547	13,016
Net Income	4,416	4,235	7,297	7,145
Capital Expenditures	4,339	5,703	8,474	10,104
Assets	537,465		537,465		529,381
Non - Regulated [Member]
Segment Reporting Information [Line Items]
Operating Revenues	3,624	3,580	7,261	7,316
Operating Income	604	493	1,167	1,020
Net Income	312	246	600	513
Capital Expenditures		13	31	118
Assets	7,831		7,831		8,887
Inter-segment Elimination [Member]
Segment Reporting Information [Line Items]
Operating Revenues	(154)	(115)	(271)	(237)
Assets	$ (6,682)		$ (6,682)		$ (7,927)