Note 10 - Intangible Assets and Goodwill - Intangible Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Finite-lived intangible asset, gross	$ 456,650	$ 473,452
Finite-lived intangible asset, accumulated amortization	(122,805)	(110,138)
Intangible Assets in Electricity Segment [Member]
Finite-lived intangible asset, gross	402,340	417,479
Finite-lived intangible asset, accumulated amortization	(104,601)	(96,250)
Intangible Assets in Storage Segment [Member]
Finite-lived intangible asset, gross	54,310	55,973
Finite-lived intangible asset, accumulated amortization	$ (18,204)	$ (13,888)