Condensed Consolidated Statements of Operations and Comprehensive Income (Unaudited) (USD $) Share data in Thousands, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Revenues:
Electricity	$ 91,692,000	$ 87,713,000	$ 186,509,000	$ 156,011,000
Product	35,911,000	64,966,000	83,530,000	115,574,000
Total revenues	127,603,000	152,679,000	270,039,000	271,585,000
Cost of revenues:
Electricity	67,322,000	58,641,000	124,356,000	113,729,000
Product	20,324,000	43,657,000	52,267,000	80,698,000
Total cost of revenues	87,646,000	102,298,000	176,623,000	194,427,000
Gross margin	39,957,000	50,381,000	93,416,000	77,158,000
Operating expenses:
Research and development expenses	232,000	1,608,000	145,000	2,608,000
Selling and marketing expenses	3,216,000	3,777,000	6,595,000	15,286,000
General and administrative expenses	6,072,000	7,134,000	13,668,000	13,718,000
Write-off of unsuccessful exploration activities	8,107,000		8,107,000
Operating income	22,330,000	37,862,000	64,901,000	45,546,000
Other income (expense):
Interest income	90,000	87,000	201,000	128,000
Interest expense, net	(22,072,000)	(17,504,000)	(42,590,000)	(33,367,000)
Foreign currency translation and transaction gains (losses)	(55,000)	904,000	(693,000)	2,586,000
Income attributable to sale of tax benefits	6,130,000	5,783,000	12,847,000	9,315,000
Gain from sale of property, plant and equipment	7,628,000		7,628,000
Other non-operating income, net	343,000	29,000	406,000	1,446,000
Income before income taxes and equity in income (losses) of investees	14,394,000	27,161,000	42,700,000	25,654,000
Income tax provision	(4,967,000)	(5,780,000)	(11,287,000)	(9,827,000)
Equity in income (losses) of investees	(114,000)	9,000	(311,000)	9,000
Income from continuing operations	9,313,000	21,390,000	31,102,000	15,836,000
Discontinued operations:
Income from discontinued operations (including gain on disposal of $0, $3,646, $0 and $3,646, respectively)		4,480,000		5,311,000
Total income from discontinued operations		4,117,000		4,697,000
Net income	9,313,000	25,507,000	31,102,000	20,533,000
Net income attributable to noncontrolling interest	(177,000)	(322,000)	(414,000)	(407,000)
Net income attributable to the Company's stockholders	9,136,000	25,185,000	30,688,000	20,126,000
Comprehensive income:
Net income	9,313,000	25,507,000	31,102,000	20,533,000
Other comprehensive income (loss), net of related taxes:
Change in unrealized gains or losses in respect of the Company's share in derivative instruments of unconsolidated investment	(4,088,000)		(4,088,000)
Amortization of unrealized gains or losses in respect of derivative instruments designated for cash flow hedge	(36,000)	(42,000)	(72,000)	(84,000)
Comprehensive income	5,189,000	25,465,000	26,942,000	20,449,000
Comprehensive income attributable to noncontrolling interest	(177,000)	(211,000)	(414,000)	(407,000)
Comprehensive income attributable to the Company's stockholders	5,012,000	25,254,000	26,528,000	20,042,000
Earnings per share attributable to the Company's stockholders - basic and diluted:
Income from continuing operations (in Dollars per share)	$ 0.20	$ 0.46	$ 0.67	$ 0.34
Discontinued operations (in Dollars per share)		$ 0.09		$ 0.10
Net income (in Dollars per share)	$ 0.20	$ 0.55	$ 0.67	$ 0.44
Weighted average number of shares used in computation of earnings per share attributable to the Company's stockholders:
Basic (in Shares)	45,606	45,431	45,545	45,431
Diluted (in Shares)	45,963	45,448	45,827	45,443
Dividend per share declared (in Dollars per share)	$ 0.05	$ 0.04	$ 0.11	$ 0.04
Discontinued Operations [Member]
Other income (expense):
Income tax provision		$ (363,000)		$ (614,000)