Derivative and Hedging Instruments (Details-1)		3 Months Ended	12 Months Ended
		Mar. 31, 2021 USD ($) Dth MWh MW	Dec. 31, 2020 USD ($) Dth MWh MW	Mar. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)
Derivative fair values [Abstract]
Collateral posted against derivative positions		$ 0	$ 0
Other Current Assets [Member]
Derivative fair values [Abstract]
Derivative fair value, net		173,000	1,162,000	$ 430,000	$ 1,100,000
Commodity Contracts And Financial Transimission Rights [Member]
Derivative fair values [Abstract]
Derivative fair value, net		$ 500,000	$ 200,000
Commodity Derivative Contracts [Member]
Gross Notional Volume of Open Derivatives
Notional amount, energy measure (in MWh) | MWh		277,400	259,080
Notional amount, decatherm measure (in Dth) | Dth		2,190,000	6,030,000
Derivative fair values [Abstract]
Asset Derivatives, fair value, gross basis		$ 683,000	$ 806,000
Liability Derivatives, fair value, gross basis		190,000	632,000
Collateral posted against derivative positions		0	0
Collateral posted against derivative positions		0	0
Commodity Derivative Contracts [Member] | Other Current Assets [Member]
Derivative fair values [Abstract]
Asset Derivatives, fair value, gross basis	[1]	653,000	617,000
Liability Derivatives, fair value, gross basis	[1]	174,000	593,000
Commodity Derivative Contracts [Member] | Other Deferred Charges [Member]
Derivative fair values [Abstract]
Asset Derivatives, fair value, gross basis	[1]	30,000	189,000
Liability Derivatives, fair value, gross basis	[1]	16,000	39,000
Commodity Derivative Contracts [Member] | Cash Flow Hedging [Member]
Derivative fair values [Abstract]
Collateral posted against derivative positions		$ 0	$ 0
Energy Related Commodity Contract [Member] | Cash Flow Hedging [Member]
Derivatives Fair Value [Line Items]
Maximum term of derivative hedging contract		4 years
Financial Transmission Rights [Member]
Gross Notional Volume of Open Derivatives
Notional amount, power measure (in MW) | MW		1,152	2,869
Derivative fair values [Abstract]
Asset Derivatives, fair value, gross basis		$ 38,000
Liability Derivatives, fair value, gross basis			$ 23,000
Collateral posted against derivative positions			0
Collateral posted against derivative positions		0
Financial Transmission Rights [Member] | Other Current Assets [Member]
Derivative fair values [Abstract]
Asset Derivatives, fair value, gross basis		38,000
Liability Derivatives, fair value, gross basis		$ 0
Financial Transmission Rights [Member] | Other Current Liabilities [Member]
Derivative fair values [Abstract]
Asset Derivatives, fair value, gross basis			0
Liability Derivatives, fair value, gross basis			$ 23,000
PPA [Member]
Gross Notional Volume of Open Derivatives
Notional amount, power measure (in MW) | MW		700	850
Derivative fair values [Abstract]
Derivative fair value, net		$ (11,600,000)	$ (14,100,000)
Liability Derivatives, fair value, gross basis		11,590,000	14,140,000
Collateral posted against derivative positions		0	0
PPA [Member] | Derivative Liability (Current) [Member]
Derivative fair values [Abstract]
Liability Derivatives, fair value, gross basis		9,790,000	10,160,000
PPA [Member] | Derivative Liability (Long-term) [Member]
Derivative fair values [Abstract]
Liability Derivatives, fair value, gross basis		$ 1,800,000	$ 3,980,000

[1] No collateral was posted against derivative positions as of March 31, 2021, and December 31, 2020