Revenue Recognition from Contracts with Customers (Schedule of Operating Revenue) (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Regulated Tariff Sales
Residential	$ 17,892	$ 17,024	$ 33,515	$ 32,183
Commercial	3,771	3,493	6,880	6,447
Industrial	2,689	2,395	5,001	4,578
Fire Protection	3,073	2,911	5,961	5,824
Wholesale	3,680	3,397	6,892	6,631
Non-Regulated Contract Operations	3,781	3,762	7,780	7,411
Total Revenue from Contracts with Customers	34,886	32,982	66,029	63,074
Other Regulated Revenues	63	48	125	98
Other Non-Regulated Revenues	101	111	202	212
Inter-segment Elimination	(131)	(127)	(260)	(239)
Total Revenue	$ 34,919	$ 33,014	$ 66,096	$ 63,145

Amount, including tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value-added and excise.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=109196051&loc=SL49130539-203045

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=109196051&loc=SL49130545-203045

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 4
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=109196051&loc=SL49130543-203045

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