Fair Value of Financial Instruments (Details-3)	3 Months Ended	12 Months Ended
	Mar. 31, 2021	Dec. 31, 2020
Basis adjustment:
Basis adjustment - on peak	94.40%	94.20%
Basis adjustment - off peak	95.00%	94.50%
US Treasury Bill Securities [Member]
Deferred compensation plan [Abstract]
Investment interest calculation, investment maturity period (26 weeks)	182 days
Investment interest calculation, monthly compounding rate	1.00%
Investment interest calculation, minimum annual rate compounded monthly	7.00%
Minimum [Member]
Counterparty fuel mix:
Internal generation	41.00%	46.00%
Purchased power	34.00%	35.00%
Maximum [Member]
Counterparty fuel mix:
Internal generation	66.00%	65.00%
Purchased power	59.00%	54.00%
Weighted Average [Member]
Counterparty fuel mix:
Internal generation	56.90%	56.50%
Purchased power	43.10%	43.50%