Note 13 - Discontinued Operations (Details) - Summary of Financial Information Related to Discontinued Operations (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Revenues - electricity	$ 88,994	$ 77,612	$ 245,005	$ 238,837
Cost of revenues - electricity:	90,993	102,054	285,420	281,360
Gross margin	39,756	30,243	116,914	107,093
Selling and marketing expenses	2,575	3,346	17,861	12,752
General and administrative expenses	6,546	6,132	20,264	20,163
Operating income	29,797	12,065	75,343	61,047
Income from discontinued operations, net of taxes		2,123	5,311	4,875
Momotombo Power Plant [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Revenues - electricity		3,840	4,866	9,873
Cost of revenues - electricity:		1,542	2,869	4,565
Gross margin		2,298	1,997	5,308
Selling and marketing expenses		99	192	281
General and administrative expenses		76	140	152
Operating income		2,123	1,665	4,875
Income from discontinued operations before income taxes		2,123	5,311	4,875
Income tax provision		(391)	(614)	(1,097)
Income from discontinued operations, net of taxes		$ 1,732	$ 4,697	$ 3,778