Business Segment Data (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013 N	Mar. 31, 2012	Dec. 31, 2012
Segment Reporting Information [Line Items]
Number of Reportable Segments	2
Operating Revenues	$ 27,038	$ 23,546
Operating Income	5,865	3,877
Net Income	3,177	1,807
Capital Expenditures	4,506	6,433
Assets	546,144		561,726
Regulated
Segment Reporting Information [Line Items]
Operating Revenues	23,424	20,858
Operating Income	5,338	3,503
Net Income	2,910	1,587
Capital Expenditures	4,401	6,039
Assets	545,108		560,165
Non - Regulated
Segment Reporting Information [Line Items]
Operating Revenues	3,736	2,758
Operating Income	527	374
Net Income	267	220
Capital Expenditures	105	394
Assets	11,089		11,674
Inter-segment Elimination
Segment Reporting Information [Line Items]
Operating Revenues	(122)	(70)
Assets	$ (10,053)		$ (10,113)