Note 6 - Investment in Unconsolidated Companies - Unconsolidated Investments Mainly in Power Plants (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Total investment in unconsolidated companies	$ 115,693	$ 105,886
Sarulla [Member]
Total investment in unconsolidated companies	74,881	68,968
Ijen Geothermal Project Company [Member]
Total investment in unconsolidated companies	$ 40,812	$ 36,918