Revenue (Details-1) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Total Operating Revenue [Member]
Disaggregation of Revenue [Line Items]
Revenues recognized from contracts with customers	$ 117,040	$ 122,147	$ 266,913	$ 289,716
Electric [Member]
Disaggregation of Revenue [Line Items]
Revenues recognized from contracts with customers	93,747	96,863	186,737	194,279
Electric [Member] | Residential [Member]
Disaggregation of Revenue [Line Items]
Revenues recognized from contracts with customers	34,874	30,749	68,302	65,330
Electric [Member] | Commercial [Member]
Disaggregation of Revenue [Line Items]
Revenues recognized from contracts with customers	47,388	52,762	95,022	102,015
Electric [Member] | Industrial [Member]
Disaggregation of Revenue [Line Items]
Revenues recognized from contracts with customers	2,763	3,322	5,563	6,253
Electric [Member] | Other-retail/municipal
Disaggregation of Revenue [Line Items]
Revenues recognized from contracts with customers	8,050	8,946	16,254	17,185
Electric [Member] | Total Retail [Member]
Disaggregation of Revenue [Line Items]
Revenues recognized from contracts with customers	93,075	95,779	185,141	190,783
Electric [Member] | Sales To The Market [Member]
Disaggregation of Revenue [Line Items]
Revenues recognized from contracts with customers	568	790	1,050	2,751
Electric [Member] | Other Revenues [Member]
Disaggregation of Revenue [Line Items]
Revenues recognized from contracts with customers	104	294	546	745
Gas [Member]
Disaggregation of Revenue [Line Items]
Revenues recognized from contracts with customers	23,079	25,070	79,924	95,170
Gas [Member] | Residential [Member]
Disaggregation of Revenue [Line Items]
Revenues recognized from contracts with customers	15,405	16,000	48,892	56,317
Gas [Member] | Commercial/Industrial [Member]
Disaggregation of Revenue [Line Items]
Revenues recognized from contracts with customers	6,438	7,883	27,909	36,008
Gas [Member] | Total Retail [Member]
Disaggregation of Revenue [Line Items]
Revenues recognized from contracts with customers	21,843	23,883	76,801	92,325
Gas [Member] | Gas Transportation [Member]
Disaggregation of Revenue [Line Items]
Revenues recognized from contracts with customers	1,232	1,094	3,026	2,630
Gas [Member] | Other Revenues [Member]
Disaggregation of Revenue [Line Items]
Revenues recognized from contracts with customers	4	93	97	215
Non Regulated Energy [Member]
Disaggregation of Revenue [Line Items]
Revenues recognized from contracts with customers	$ 214	$ 214	$ 252	$ 267