Note 10 - Intangible Assets and Goodwill (Details Textual) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Finite-Lived Intangible Assets, Net, Ending Balance	$ 333,845
Finite-Lived Intangible Assets, Accumulated Amortization	122,805	$ 110,138
Amortization of Intangible Assets	27,200	21,700	$ 14,400
Increase (Decrease) in Intangible Assets, Current	0	192,500	20,400
Finite Lived Intangible Assets, Write off	900	0	0
Goodwill, Ending Balance	90,325	89,954	24,566
Goodwill, Impairment Loss	0	0	$ 0
Power Purchase Agreements and Intangible Assets Related to Storage Activities [Member]
Finite-Lived Intangible Assets, Net, Ending Balance	333,800	363,300
Finite-Lived Intangible Assets, Accumulated Amortization	$ 122,800	$ 110,100