Derivative and Hedging Instruments (Details-4) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Current and Long-Term Regulatory Asset [Member]
Change In Derivative Fair Value [Roll Forward]
Beginning balance,	$ 13,989	$ 26,875
Unrealized (gain) loss	(3,588)	(689)
Realized (loss) gain reclassified to a deferred account	(50)	(1,063)
Realized (loss) gain reclassified to income statement	708	204
Ending balance,	11,059	25,327
Other Current Assets [Member]
Change In Derivative Fair Value [Roll Forward]
Beginning balance,	1,162	1,100
Unrealized (gain) loss	0	0
Realized (loss) gain reclassified to a deferred account	50	1,063
Realized (loss) gain reclassified to income statement	(1,039)	(1,733)
Ending balance,	$ 173	$ 430