Note 7 - Property, Plant and Equipment and Construction-in-Process (Tables)

12 Months Ended

Dec. 31, 2014

Property, Plant and Equipment [Abstract]

Property, Plant and Equipment [Table Text Block]

	December 31,
	2014			2013
	(Dollars in thousands)
Land owned by the Company where the geothermal resource is located	$	31,465		$	30,336
Leasehold improvements		3,420			3,386
Machinery and equipment		123,807			101,104
Office equipment		17,150			17,492
Automobiles		6,495			5,745
Geothermal and recovered energy generation power plants, including geothermal wells and exploration and resource development costs:
United States of America, net of cash grants and impairment charges		1,463,291			1,439,374
Foreign countries		473,481			448,161
Asset retirement cost		7,444			7,803
		2,126,553			2,053,401
Less accumulated depreciation		(688,916	)		(601,065	)
Property, plant and equipment, net	$	1,437,637		$	1,452,336

Construction-in-Progress [Table Text Block]

	December 31,
	2014		2013
	(Dollars in thousands)
Projects under exploration and development:
Up-front bonus lease costs	$	26,618	$	30,141
Exploration and development costs		45,977		38,220
Interest capitalized		836		1,278
		73,431		69,639
Projects under construction:
Up-front bonus lease costs		27,473		27,473
Drilling and construction costs		187,545		184,767
Interest capitalized		8,273		6,948
		223,291		219,188
Total	$	296,722	$	288,827

Roll Forward of Construction-in-Process [Table Text Block]

	Projects under Exploration and Development
	Up-front Bonus Lease Costs			Exploration and Development Costs			Interest Capitalized			Total
	(Dollars in thousands)
Balance at December 31, 2011	$	36,832		$	40,223		$	1,598		$	78,653
Cost incurred during the year		—			3,782			420			4,203
Write off of unsuccessful exploration costs		(1,160	)		(1,479	)		—			(2,639	)
Transfer of projects under exploration and development to projects under construction		(1,687	)		(10,224	)		(740	)		(12,651	)
Balance at December 31, 2012		33,985			32,302			1,278			67,565
Cost incurred during the year		—			6,168			—			6,168
Write off of unsuccessful exploration costs		(3,844	)		(250	)		—			(4,094	)
Balance at December 31, 2013		30,141			38,220			1,278			69,639
Cost incurred during the year		—			19,231			—			19,231
Write off of unsuccessful exploration costs		(3,523	)		(11,474	)		(442	)		(15,439	)
Balance at December 31, 2014	$	26,618		$	45,977		$	836		$	73,431

	Projects under Construction
	Up-front Bonus Lease Costs			Drilling and Construction Costs			Interest Capitalized			Total
	(Dollars in thousands)
Balance at December 31, 2011	$	31,179		$	246,878		$	13,841		$	291,898
Cost incurred during the year		—			216,894			11,542			228,435
Transfer of completed projects to property, plant and equipment		1,687			10,224			740			12,651
Transfer from projects under exploration and development		(3,706	)		(190,123	)		(10,579	)		(204,408	)
Balance at December 31, 2012		29,160			283,873			15,543			328,576
Cost incurred during the year		—			203,859			7,609			211,468
Transfer from projects under exploration and development		(1,687	)		(302,966	)		(16,204	)		(320,857	)
Balance at December 31, 2013		27,473			184,766			6,948			219,187
Cost incurred during the year		—			132,597			3,206			135,803
Sale of property, plant and equipment		—			(24,692	)		(911	)		(25,603	)
Reclassification of completed projects to property, plant and equipment		—			(105,126	)		(970	)		(106,096	)
Balance at December 31, 2014	$	27,473		$	187,545		$	8,273		$	223,291