Note 5 - Investment in an Unconsolidated Company - Unconsolidated Investments Mainly in Power Plants (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Total investment in unconsolidated companies	$ 81,140	$ 71,983
Sarulla [Member]
Total investment in unconsolidated companies	70,589	71,983
Ijen Geothermal Project Company [Member]
Total investment in unconsolidated companies	$ 10,551	$ 0