Condensed Consolidated Statements of Operations and Comprehensive Income (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Revenues:
Total consolidated revenues	$ 184,023	$ 189,898	[1]
Cost of revenues:
Cost of revenues	110,651	115,488
Gross profit	73,372	74,410
Operating expenses:
Research and development expenses	1,108	602
Selling and marketing expenses	3,699	4,363
General and administrative expenses	13,849	9,949
Write-off of unsuccessful exploration activities	123	0
Operating income	54,593	59,496	[1]
Other income (expense):
Interest income	113	244
Interest expense, net	(14,344)	(14,923)
Derivatives and foreign currency transaction gains (losses)	(1,599)	1,338
Income attributable to sale of tax benefits	7,361	6,157
Other non-operating expense, net	(20)	(92)
Income from continuing operations before income taxes and equity in earnings (losses) of investees	46,104	52,220
Income tax (provision) benefit	26,942	(11,004)
Equity in earnings (losses) of investees, net	1,210	(1,599)
Income from continuing operations	74,256	39,617
Net income attributable to noncontrolling interest	(4,748)	(4,423)
Net income attributable to the Company's stockholders	69,508	35,194
Comprehensive income:
Net income	74,256	39,617
Other comprehensive income (loss), net of related taxes:
Change in foreign currency translation adjustments	1,528
Change in unrealized gains or losses in respect of the Company's share in derivatives instruments of unconsolidated investment	2,634	569
Loss in respect of derivative instruments designated for cash flow hedge	20	48
Amortization of unrealized gains in respect of derivative instruments designated for cash flow hedge	(15)	(24)
Comprehensive income	78,423	40,210
Comprehensive income attributable to noncontrolling interest	(5,118)	(4,412)
Comprehensive income attributable to the Company's stockholders	$ 73,305	$ 35,798
Basic:
Net income (in dollars per share)	$ 1.37	$ 0.71
Diluted:
Net income (in dollars per share)	$ 1.36	$ 0.70
Weighted average number of shares used in computation of earnings per share attributable to the Company's stockholders:
Basic (in shares)	50,614	49,680
Diluted (in shares)	51,051	50,491
Dividend per share declared (in dollars per share)	$ 0.23	$ 0.17
Electricity [Member]
Revenues:
Total consolidated revenues	$ 132,489	$ 115,776
Cost of revenues:
Cost of revenues	73,482	66,036
Product [Member]
Revenues:
Revenues	48,672	74,122
Cost of revenues:
Cost of revenues	33,726	49,452
Other Revenue [Member]
Revenues:
Revenues	2,862
Cost of revenues:
Cost of revenues	$ 3,443

[1] The amounts related to the Other segment are immaterial.