Note 10 - Intangible Assets and Goodwill - Intangible Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Finite-lived intangible asset, gross	$ 473,452	$ 283,784
Finite-lived intangible asset, accumulated amortization	(110,138)	(89,363)
Intangible Assets in Electricity Segment [Member]
Finite-lived intangible asset, gross	417,479	227,811
Finite-lived intangible asset, accumulated amortization	(96,250)	(80,622)
Intangible Assets in Storage Segment [Member]
Finite-lived intangible asset, gross	55,973	55,973
Finite-lived intangible asset, accumulated amortization	$ (13,888)	$ (8,741)