Note 9 - Intangible Assets and Goodwill (Tables)

12 Months Ended

Dec. 31, 2023

Notes Tables

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

	December 31, 2023					December 31, 2022
	Gross Carrying Amount		Accumulated Amortization			Gross Carrying Amount		Accumulated Amortization
	(Dollars in thousands)					(Dollars in thousands)
Amortized intangible assets
Electricity segment	$	403,511	$	(127,324	)	$	402,340	$	(104,601	)
Storage segment		54,310		(22,888	)		54,310		(18,204	)
Total	$	457,821	$	(150,212	)	$	456,650	$	(122,805	)

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

	(Dollars in thousands)
Year ending December 31:
2024	$	26,277
2025		25,911
2026		24,056
2027		22,176
2028		21,903
Thereafter		187,286
Total	$	307,609

Schedule of Goodwill [Table Text Block]

	2023		2022
	(Dollars in thousands)
Goodwill as of January 1,	$	90,325	$	89,954
Translation differences		219		371
Goodwill as of December 31,	$	90,544	$	90,325