Note 10 - Intangible Assets and Goodwill (Tables)

12 Months Ended

Dec. 31, 2022

Notes Tables

Schedule of Finite-Lived Intangible Assets [Table Text Block]

	December 31, 2022					December 31, 2021
	Gross Carrying Amount		Accumulated Amortization			Gross Carrying Amount		Accumulated Amortization
	(Dollars in thousands)					(Dollars in thousands)
Amortized intangible assets
Electricity segment	$	402,340	$	(104,601	)	$	417,479	$	(96,250	)
Storage segment		54,310		(18,204	)		55,973		(13,888	)
Total	$	456,650	$	(122,805	)	$	473,452	$	(110,138	)

Schedule of Finite-Lived Intangible Assets, Future Amortization Expense [Table Text Block]

	(Dollars in thousands)
Year ending December 31:
2023	$	27,191
2024		26,229
2025		25,911
2026		24,056
2027		22,176
Thereafter		208,282
Total	$	333,845

Schedule of Goodwill [Table Text Block]

	2022		2021
	(Dollars in thousands)
Goodwill as of January 1,	$	89,954	$	24,566
Goodwill acquired (1)		—		65,441
Translation differences		371		(53	)
Goodwill as of December 31,	$	90,325	$	89,954