Fair Value of Financial Instruments (Details-3)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Basis adjustment:
Basis adjustment - on peak	94.20%	92.10%
Basis adjustment - off peak	94.50%	92.70%
US Treasury Bills [Member]
Deferred compensation plan
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	46.00%	40.00%
Purchased power	35.00%	40.00%
Maximum [Member]
Counterparty fuel mix:
Internal generation	65.00%	60.00%
Purchased power	54.00%	60.00%
Weighted Average [Member]
Counterparty fuel mix:
Internal generation	56.50%	52.20%
Purchased power	43.50%	47.80%