Note 9 - Intangible Assets and Goodwill - Intangible Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Finite-lived intangible asset, gross	$ 457,821	$ 456,650
Finite-lived intangible asset, accumulated amortization	(150,212)	(122,805)
Intangible Assets in Electricity Segment [Member]
Finite-lived intangible asset, gross	403,511	402,340
Finite-lived intangible asset, accumulated amortization	(127,324)	(104,601)
Intangible Assets in Storage Segment [Member]
Finite-lived intangible asset, gross	54,310	54,310
Finite-lived intangible asset, accumulated amortization	$ (22,888)	$ (18,204)