Consolidated Statements of Cash Flows $ in Thousands	12 Months Ended
	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)
Cash flows from operating activities:
Net income	$ 110,111	$ 147,109	$ 96,294
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	132,233	115,146	105,977
Amortization of premium from senior unsecured bonds			(513)
Accretion of asset retirement obligation	2,474	1,874	1,778
Stock-based compensation	10,218	8,760	5,157
Amortization of deferred lease income	(2,685)	(2,685)	(2,685)
Income attributable to sale of tax benefits, net of interest expense	(8,609)	(11,956)	(6,962)
Equity in losses (earnings) of investees	(7,663)	1,957	7,735
Mark-to-market of derivative instruments	2,032	(1,473)	319
Write-off of unsuccessful exploration activities	126	1,796	3,017
Impairment charge	13,464
Loss (gain) on severance pay fund asset	1,186	(1,746)	(304)
Deferred income tax provision and deferred charges	19,360	(41,147)	23,222
Liability for unrecognized tax benefits	2,879	3,270	(4,174)
Deferred lease revenues	(402)	(356)	(853)
Gain from insurance recoveries	(4,463)
Other	100	737
Changes in operating assets and liabilities, net of businesses acquired:
Receivables	(29,928)	(24,040)	(33,280)
Costs and estimated earnings in excess of billings on uncompleted contracts	(1,185)	11,253	(27,078)
Inventories	(9,318)	(1,070)	6,297
Prepaid expenses and other	(11,172)	208	(12,540)
Deposits and other	18	(2,570)	(1,009)
Accounts payable and accrued expenses	(56,724)	51,641	(1,375)
Billings in excess of costs and estimated earnings on uncompleted contracts	(1,839)	(11,389)	(2,262)
Liabilities for severance pay	(3,147)	2,541	(786)
Other long-term liabilities	(11,244)	(2,285)	3,310
Net cash provided by operating activities	145,822	245,575	159,285
Cash flows from investing activities:
Capital expenditures	(258,521)	(259,234)	(151,930)
Cash received from insurance recoveries related to destroyed equipment	10,427
Investment in unconsolidated companies	(3,800)	(46,318)	(3,569)
Cash paid for acquisition of controlling interest in a subsidiary, net of cash acquired	(95,093)	(35,300)	(20,135)
Intangible assets acquired		(868)
Decrease (increase) in severance pay fund asset, net of payments made to retired employees	2,186	526	1,862
Net cash used in investing activities	(342,434)	(345,526)	(173,772)
Cash flows from financing activities:
Proceeds from sale of membership interests to noncontrolling interest, net of transaction costs	3,174		44,102
Proceeds from long-term loans, net of transaction costs	214,700		142,500
Proceeds from exercise of options by employees		16,111	7,249
Proceeds from issuance of senior unsecured notes, net of transaction costs			203,483
Purchase of Senior unsecured notes			(249,468)
Proceeds from the sale of limited liability company interest in Tungsten, net of transaction costs	4,134	2,017	1,972
Purchase of OFC Senior Secured Notes		(14,270)	(6,815)
Proceeds from revolving credit lines with banks	4,097,000	1,097,500	309,400
Repayment of revolving credit lines with banks	(3,989,500)	(1,046,000)	(309,400)
Cash paid for achievement of production threshold in GB		(8,032)
Repayments of long-term debt	(62,774)	(66,223)	(62,052)
Cash paid to noncontrolling interest	(13,106)	(21,313)	(64,065)
Payments of capital leases	(2,551)	(1,871)	(1,178)
Deferred debt issuance costs	(5,287)	(5,290)	(6,402)
Cash dividends paid	(26,834)	(20,511)	(25,682)
Net cash provided by (used in) financing activities	251,131	(67,882)	43,541
Effect of exchange rate changes	(660)
Net change in cash and cash equivalents and restricted cash and cash equivalents	53,859	(167,833)	29,054
Restricted cash and cash equivalents acquired in a business combination	26,993
Cash and cash equivalents and restricted cash and cash equivalents at beginning of period	96,643	264,476	235,422
Cash and cash equivalents and restricted cash and cash equivalents at end of period	177,495	96,643	264,476
Supplemental disclosure of cash flow information:
Interest, net of interest capitalized	53,864	40,484	55,366
Income taxes, net	18,028	21,878	18,490
Supplemental non-cash investing and financing activities:
Increase (decrease) in accounts payable related to purchases of property, plant and equipment	(6,878)	4,484	(2,219)
Accrued liabilities related to financing activities	8,584		6,291
Increase (decrease) in asset retirement cost and asset retirement obligation	881	1,888	714
Tungsten [Member]
Cash flows from financing activities:
Proceeds from the sale of limited liability company interest in Tungsten, net of transaction costs	32,175		59,897
Ormat Nevada ORTP LLC [Member]
Cash flows from investing activities:
Buyout of Class B membership in ORTP		(2,400)
OPC LLC [Member]
Cash flows from investing activities:
Buyout of Class B membership in OPC	$ 2,367	$ (1,932)