Note 19 - Business Segments (Details) - Long Lived Assets (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Long-lived assets (primarily power plants and related assets) located in:
Long-lived assets locations	$ 1,790,071	$ 1,803,274	$ 1,715,877
North America [Member]
Long-lived assets (primarily power plants and related assets) located in:
Long-lived assets locations	1,369,136	1,387,449	1,358,877
Latin America [Member]
Long-lived assets (primarily power plants and related assets) located in:
Long-lived assets locations	76,601	63,972	67,536
Africa [Member]
Long-lived assets (primarily power plants and related assets) located in:
Long-lived assets locations	330,200	338,395	274,395
Europe [Member]
Long-lived assets (primarily power plants and related assets) located in:
Long-lived assets locations	13,272	12,787	14,859
Pacific Rim and Far East [Member]
Long-lived assets (primarily power plants and related assets) located in:
Long-lived assets locations	$ 862	$ 671	$ 210