Ormat (ORA) 10-Q 8 Nov 18 2018 Q3 Quarterly report Financial data

Document And Entity Information

Document And Entity Information - shares	9 Months Ended
	Sep. 30, 2018	Nov. 06, 2018
Document Information [Line Items]
Entity Registrant Name	ORMAT TECHNOLOGIES, INC.
Entity Central Index Key	1,296,445
Trading Symbol	ora
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Current Reporting Status	Yes
Entity Emerging Growth Company	false
Entity Small Business	false
Entity Common Stock, Shares Outstanding (in shares)		50,672,520
Document Type	10-Q
Document Period End Date	Sep. 30, 2018
Document Fiscal Year Focus	2,018
Document Fiscal Period Focus	Q3
Amendment Flag	false

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets (Current Period Unaudited) - USD ($) $ in Thousands	Sep. 30, 2018		Dec. 31, 2017
Current assets:
Cash and cash equivalents	$ 71,965		$ 47,818
Restricted cash and cash equivalents (primarily related to VIEs)	83,101		48,825
Receivables:
Trade	118,675		110,410
Other	18,328		13,828
Inventories	37,442		19,551
Costs and estimated earnings in excess of billings on uncompleted contracts	47,811		40,945
Prepaid expenses and other	44,452		40,269
Total current assets	421,774		321,646
Investment in an unconsolidated company	67,739		34,084
Deposits and other	20,109		21,599
Deferred income taxes	113,363		57,337
Deferred charges			49,834
Property, plant and equipment, net	1,835,939		1,734,691
Construction-in-process	351,288		293,542
Deferred financing and lease costs, net	5,878		4,674
Intangible assets, net	203,382		85,420
Goodwill	40,111		21,037
Total assets	3,059,583	[1]	2,623,864
Current liabilities:
Accounts payable and accrued expenses	105,351		153,796
Short term revolving credit lines with banks (full recourse)	209,500		51,500
Billings in excess of costs and estimated earnings on uncompleted contracts	21,760		20,241
Current portion of long-term debt:
Senior secured notes	33,259		33,226
Other loans	21,495		21,495
Full recourse	5,000		3,087
Total current liabilities	396,365		283,345
Long-term debt, net of current portion:
Senior secured notes (less deferred financing costs of $7,758 and $8,113, respectively)	386,379		311,668
Other loans (less deferred financing costs of $4,823 and $5,258, respectively)	225,782		242,385
Senior unsecured bonds (less deferred financing costs of $804 and $580, respectively)	303,528		203,752
Other loans (less deferred financing costs of $1,058 and $1,011, respectively)	43,942		46,489
Liability associated with sale of tax benefits	69,071		44,634
Deferred lease income	49,203		51,520
Deferred income taxes	56,753		61,961
Liability for unrecognized tax benefits	10,139		8,890
Liabilities for severance pay	19,903		21,141
Asset retirement obligation	37,946		27,110
Other long-term liabilities	22,354		18,853
Total liabilities	1,621,365		1,321,748
Commitments and contingencies (Note 10)
Redeemable noncontrolling interest	8,522		6,416
Equity:
Common stock, par value $0.001 per share; 200,000,000 shares authorized; 50,672,520 and 50,609,051 shares issued and outstanding as of September 30, 2018 and December 31, 2017, respectively	51		51
Additional paid-in capital	896,160		888,778
Retained earnings	410,870		327,255
Accumulated other comprehensive income (loss)	(1,386)		(4,706)
Total stockholders' equity attributable to Company's stockholders	1,305,695		1,211,378
Noncontrolling interest	124,001		84,322
Total equity	1,429,696		1,295,700
Total liabilities, redeemable noncontrolling interest and equity	$ 3,059,583		$ 2,623,864
[1]	Electricity segment assets include goodwill in the amount of $26.7 million and $6.8 million as of September 30, 2018 and 2017, respectively. Other segment assets include goodwill in the amount of $13.5 million as of September 30, 2018 and 2017.

Condensed Consolidated Balanc_2

Condensed Consolidated Balance Sheets (Current Period Unaudited) (Parentheticals) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Property, plant and equipment, net	$ 1,835,939	$ 1,734,691
Construction-in-process	$ 351,288	$ 293,542
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common stock, shares authorized (in shares)	200,000,000	200,000,000
Common stock, shares issued (in shares)	50,672,520	50,609,051
Common stock, shares outstanding (in shares)	50,672,520	50,609,051
Senior Secured Notes [Member]
Deferred financing costs	$ 7,758	$ 8,113
Other Loans, Limited and Non-recourse [Member]
Deferred financing costs	4,823	5,258
Senior Unsecured Bonds [Member]
Deferred financing costs	804	580
Other Loans, Full Recourse [Member]
Deferred financing costs	1,058	1,011
Variable Interest Entity, Primary Beneficiary [Member]
Property, plant and equipment, net	1,744,299	1,631,900
Construction-in-process	$ 106,977	$ 142,717

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations and Comprehensive Income (Unaudited) - USD ($) shares in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Revenues:
Total consolidated revenues	$ 166,480,000	$ 157,185,000	$ 528,802,000	$ 526,447,000
Cost of revenues:
Cost of revenues	117,688,000	97,992,000	349,176,000	322,351,000
Gross profit	48,792,000	59,193,000	179,626,000	204,096,000
Operating expenses:
Research and development expenses	706,000	716,000	3,065,000	2,368,000
Selling and marketing expenses	8,578,000	3,630,000	15,989,000	12,083,000
General and administrative expenses	13,606,000	10,877,000	43,325,000	33,027,000
Write-off of unsuccessful exploration activities	0	0	119,000	0
Operating income	25,902,000	43,970,000	117,128,000	156,618,000
Other income (expense):
Interest income	214,000	255,000	516,000	861,000
Interest expense, net	(18,700,000)	(11,692,000)	(48,890,000)	(41,155,000)
Derivatives and foreign currency transaction gains (losses)	(383,000)	(1,001,000)	(2,511,000)	2,040,000
Income attributable to sale of tax benefits	4,066,000	3,506,000	14,983,000	14,019,000
Other non-operating income (expense), net	309,000	(1,592,000)	7,662,000	(1,678,000)
Income from continuing operations before income taxes and equity in earnings (losses) of investees	11,408,000	33,446,000	88,888,000	130,705,000
Income tax (provision) benefit	(1,184,000)	(6,224,000)	(3,347,000)	(49,993,000)
Equity in earnings (losses) of investees, net	(117,000)	337,000	1,481,000	(1,690,000)
Income from continuing operations	10,107,000	27,559,000	87,022,000	79,022,000
Net income attributable to noncontrolling interest	474,000	(3,599,000)	(7,276,000)	(11,228,000)
Net income attributable to the Company's stockholders	10,581,000	23,960,000	79,746,000	67,794,000
Comprehensive income:
Net income	10,107,000	27,559,000	87,022,000	79,022,000
Other comprehensive income (loss), net of related taxes:
Change in foreign currency translation adjustments	(91,000)	1,005,000	(1,059,000)	2,544,000
Change in unrealized gains or losses in respect of the Company's share in derivatives instruments of unconsolidated investment	1,012,000	618,000	4,175,000	271,000
Loss in respect of derivative instruments designated for cash flow hedge	20,000	20,000	60,000	113,000
Amortization of unrealized gains in respect of derivative instruments designated for cash flow hedge	(14,000)	(18,000)	(44,000)	(57,000)
Comprehensive income	11,034,000	29,184,000	90,154,000	81,893,000
Comprehensive income attributable to noncontrolling interest	458,000	(4,006,000)	(7,088,000)	(11,950,000)
Comprehensive income attributable to the Company's stockholders	$ 11,492,000	$ 25,178,000	$ 83,066,000	$ 69,943,000
Earnings per share attributable to the Company's stockholders:
Net income (in dollars per share)	$ 0.21	$ 0.48	$ 1.58	$ 1.36
Diluted:
Net income (in dollars per share)	$ 0.21	$ 0.47	$ 1.56	$ 1.34
Weighted average number of shares used in computation of earnings per share attributable to the Company's stockholders:
Basic (in shares)	50,645	50,367	50,627	49,942
Diluted (in shares)	50,963	50,867	50,985	50,669
Electricity [Member]
Revenues:
Revenues	$ 116,891,000	$ 110,876,000	$ 371,559,000	$ 337,548,000
Cost of revenues:
Cost of revenues	79,845,000	64,444,000	234,563,000	193,676,000
Product [Member]
Revenues:
Revenues	48,439,000	44,912,000	152,026,000	186,621,000
Cost of revenues:
Cost of revenues	35,669,000	32,218,000	106,968,000	125,102,000
Other Revenue [Member]
Revenues:
Revenues	1,150,000	1,397,000	5,217,000	2,278,000
Cost of revenues:
Cost of revenues	$ 2,174,000	$ 1,330,000	$ 7,645,000	$ 3,573,000

Consolidated Statements of Equi

Consolidated Statements of Equity (Unaudited) - USD ($) $ in Thousands	Guadeloupe [Member]Common Stock [Member]	Guadeloupe [Member]Additional Paid-in Capital [Member]	Guadeloupe [Member]Retained Earnings [Member]	Guadeloupe [Member]AOCI Attributable to Parent [Member]	Guadeloupe [Member]Parent [Member]	Guadeloupe [Member]Noncontrolling Interest [Member]	Guadeloupe [Member]	Tungsten [Member]Common Stock [Member]	Tungsten [Member]Additional Paid-in Capital [Member]	Tungsten [Member]Retained Earnings [Member]	Tungsten [Member]AOCI Attributable to Parent [Member]	Tungsten [Member]Parent [Member]	Tungsten [Member]Noncontrolling Interest [Member]	Tungsten [Member]	U.S. Geothermal [Member]Common Stock [Member]	U.S. Geothermal [Member]Additional Paid-in Capital [Member]	U.S. Geothermal [Member]Retained Earnings [Member]	U.S. Geothermal [Member]AOCI Attributable to Parent [Member]	U.S. Geothermal [Member]Parent [Member]	U.S. Geothermal [Member]Noncontrolling Interest [Member]	U.S. Geothermal [Member]	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	AOCI Attributable to Parent [Member]	Parent [Member]	Noncontrolling Interest [Member]	Total
Balance (in shares) at Dec. 31, 2016																						49,667
Balance at Dec. 31, 2016																						$ 50	$ 869,463	$ 215,352	$ (8,175)	$ 1,076,690	$ 91,582	$ 1,168,272
Stock-based compensation																							7,204			7,204		7,204
Exercise of options by employees and directors (in shares)																						930
Exercise of options by employees and directors																						$ 1	16,382			16,383		16,383
Cash paid to noncontrolling interest																											(18,032)	(18,032)
Cash dividend declared																								(16,612)		(16,612)		(16,612)
Buyout of class B membership in ORTP																							2,956			2,956	(6,964)	(4,008)
Net income																								67,794		67,794	10,154	77,948
Other comprehensive income (loss), net of related taxes:
Currency translation adjustment																									1,822	1,822	722	2,544
Loss in respect of derivative instruments designated for cash flow hedge																									113	113		113
Change in unrealized gains or losses in respect of the Company's share in derivative instruments of unconsolidated investment (net of related tax of $0)																									271	271		271
Amortization of unrealized gains in respect of derivative instruments designated for cash flow hedge																									(57)	(57)		(57)
Balance (in shares) at Dec. 31, 2016																						49,667
Balance at Dec. 31, 2016																						$ 50	869,463	215,352	(8,175)	1,076,690	91,582	1,168,272
Other comprehensive income (loss), net of related taxes:
Stock-based compensation																							7,204			7,204		7,204
Exercise of options by employees and directors (in shares)																						930
Exercise of options by employees and directors																						$ 1	16,382			16,383		16,383
Cash paid to noncontrolling interest																											(18,032)	(18,032)
Cash dividend declared																								(16,612)		(16,612)		(16,612)
Net income																								67,794		67,794	10,154	77,948
Balance (in shares) at Sep. 30, 2017																						50,597
Balance at Sep. 30, 2017																						$ 51	896,005	266,534	(6,026)	1,156,564	77,462	1,234,026
Balance (in shares) at Dec. 31, 2017																						50,609
Balance at Dec. 31, 2017																						$ 51	888,778	327,255	(4,706)	1,211,378	84,322	1,295,700
Stock-based compensation																							7,382			7,382		7,382
Exercise of options by employees and directors (in shares)																						21
Exercise of options by employees and directors
Cash paid to noncontrolling interest																											(7,902)	(7,902)
Cash dividend declared																								(21,766)		(21,766)		(21,766)
Net income																								79,746		79,746	6,536	86,282
Other comprehensive income (loss), net of related taxes:
Currency translation adjustment																									(871)	(871)	(188)	(1,059)
Loss in respect of derivative instruments designated for cash flow hedge																									60	60		60
Change in unrealized gains or losses in respect of the Company's share in derivative instruments of unconsolidated investment (net of related tax of $0)																									4,175	4,175		4,175
Amortization of unrealized gains in respect of derivative instruments designated for cash flow hedge																									(44)	(44)		(44)
Balance (in shares) at Dec. 31, 2017																						50,609
Balance at Dec. 31, 2017																						$ 51	888,778	327,255	(4,706)	1,211,378	84,322	1,295,700
Other comprehensive income (loss), net of related taxes:
Stock-based compensation																							7,382			7,382		7,382
Exercise of options by employees and directors (in shares)																						21
Exercise of options by employees and directors
Cumulative effect of changes in accounting principles at Dec. 31, 2017																								25,635		25,635		25,635
Other comprehensive income (loss), net of related taxes:
Cash paid to noncontrolling interest																											(7,902)	(7,902)
Cash dividend declared																								(21,766)		(21,766)		(21,766)
Increase in noncontrolling interest						$ 5,339	$ 5,339						$ 996	$ 996						$ 34,898	$ 34,898
Net income																								79,746		79,746	6,536	86,282
Balance (in shares) at Sep. 30, 2018																						50,630
Balance at Sep. 30, 2018																						$ 51	$ 896,160	$ 410,870	$ (1,386)	$ 1,305,695	$ 124,001	$ 1,429,696

Consolidated Statements of Eq_2

Consolidated Statements of Equity (Unaudited) (Parentheticals) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Retained Earnings [Member]
Cash dividend declared, per share (in dollars per share)	$ 0.43	$ 0.33
Amortization of unrealized gains, tax	$ 18	$ 35
Loss in respect of derivative instruments designated for cash flow hedge, related tax	24
Change in unrealized gains or losses in respect of the Company's share in derivative instruments of unconsolidated investment, tax.	$ 0	$ 0

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($)	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Cash flows from operating activities:
Net income	$ 87,022,000	$ 79,022,000
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	98,371,000	81,010,000
Accretion of asset retirement obligation	1,826,000	1,392,000
Stock-based compensation	7,382,000	7,204,000
Amortization of deferred lease income	(2,014,000)	(2,014,000)
Income attributable to sale of tax benefits, net of interest expense	(9,806,000)	(8,851,000)
Equity in losses (earnings) of investees	(1,774,000)	1,690,000
Mark-to-market of derivative instruments	1,202,000	(764,000)
Loss on disposal of property, plant and equipment	5,365,000
Write-off of unsuccessful exploration activities	119,000	0
Loss (gain) on severance pay fund asset	630,000	(1,463,000)
Deferred income tax provision and deferred charges	(6,612,000)	38,123,000
Liability for unrecognized tax benefits	1,249,000	568,000
Deferred lease revenues	(303,000)	(274,000)
Gain from insurance recoveries	(7,150,000)
Other		501,000
Changes in operating assets and liabilities, net of amounts acquired:
Receivables	(9,704,000)	(10,808,000)
Costs and estimated earnings in excess of billings on uncompleted contracts	(6,866,000)	10,111,000
Inventories	(1,728,000)	(209,000)
Prepaid expenses and other	(4,183,000)	(636,000)
Deposits and other	10,000	1,231,000
Accounts payable and accrued expenses	(50,056,000)	(3,655,000)
Billings in excess of costs and estimated earnings on uncompleted contracts	(1,519,000)	25,344,000
Liabilities for severance pay	(1,238,000)	1,764,000
Other long-term liabilities	(105,000)	(2,065,000)
Net cash provided by operating activities	103,156,000	166,533,000
Cash flows from investing activities:
Capital expenditures	(200,657,000)	(177,410,000)
Cash received from insurance recoveries related to destroyed equipment	7,150,000
Investment in unconsolidated companies	(3,800,000)	(37,867,000)
Buyout of Class B membership in ORTP		(2,357,000)
Cash paid for acquisition of controlling interest in a subsidiary, net of cash acquired	(95,093,000)	(35,300,000)
Intangible assets acquired		(868,000)
Decrease (increase) in severance pay fund asset, net of payments made to retired employees	850,000	529,000
Net cash used in investing activities	(291,550,000)	(253,273,000)
Cash flows from financing activities:
Proceeds from sale of membership interests to noncontrolling interest, net of transaction costs	3,174,000
Proceeds from long-term loans, net of transaction costs	100,000,000
Proceeds from exercise of options by employees		16,382,000
Proceeds from the sale of limited liability company interest in Tungsten, net of transaction costs	4,134,000	2,017,000
Purchase of OFC Senior Secured Notes		(14,270,000)
Proceeds from revolving credit lines with banks	2,819,800,000	695,600,000
Repayment of revolving credit lines with banks	(2,661,800,000)	(661,700,000)
Repayments of long-term debt	(41,858,000)	(55,226,000)
Cash paid to noncontrolling interest	(9,555,000)	(18,032,000)
Payments of capital leases	(1,706,000)	(1,472,000)
Deferred debt issuance costs	(3,002,000)	(4,652,000)
Cash dividends paid	(21,766,000)	(16,612,000)
Net cash provided by (used in) financing activities	219,824,000	(57,965,000)
Net change in cash and cash equivalents and restricted cash and cash equivalents	31,430,000	(144,705,000)
Restricted cash and cash equivalents acquired in a business combination	26,993,000
Cash and cash equivalents and restricted cash and cash equivalents at beginning of period	96,643,000	264,476,000
Cash and cash equivalents and restricted cash and cash equivalents at end of period	155,066,000	119,771,000
Supplemental non-cash investing and financing activities:
Increase (decrease) in accounts payable related to purchases of property, plant and equipment	(10,390,000)	982,000
Accrued liabilities related to financing activities	5,864,000
Tungsten [Member]
Cash flows from financing activities:
Proceeds from the sale of limited liability company interest in Tungsten, net of transaction costs	$ 32,403,000

Note 1 - General and Basis of P

Note 1 - General and Basis of Presentation	9 Months Ended
	Sep. 30, 2018
Notes to Financial Statements
Organization, Consolidation and Presentation of Financial Statements Disclosure [Text Block]	NOTE 1 These unaudited condensed consolidated interim financial statements of Ormat Technologies, Inc. and its subsidiaries (collectively, the “Company”) have been prepared in accordance with accounting principles generally accepted in the United States of America (“U.S. GAAP”) and pursuant to the rules and regulations of the Securities and Exchange Commission (“SEC”) for interim financial statements. Accordingly, they do not September 30, 2018, three nine September 30, 2018 2017 nine September 30, 2018 2017. The financial data and other information disclosed in the notes to the condensed consolidated financial statements related to these periods are unaudited. The results for the three nine September 30, 2018 not December 31, 2018. These condensed unaudited consolidated financial statements should be read in conjunction with the audited consolidated financial statements and notes thereto included in the Company’s Annual Report on Form 10 December 31, 2017. December 31, 2017 December 31, 2017 not Dollar amounts, except per share data, in the notes to these financial statements are rounded to the closest $1,000. Galena 2 On September 30, 2018, 2 $5 2 2 March 2019. three nine September 30, 2018 Tungsten Mountain partnership transaction On May 17, 2018, one 26 $33.4 $13 Under the agreements, prior to December 31, 2026 ( 97.5% 95.0% On the Target Flip Date, Ormat Nevada has the option to purchase the private investor’s interests at the then-current fair market value, plus an amount that may Puna On May 3, 2018, 38 three $4.9 second 2018. $7.2 U.S. Geothermal (“USG”) transaction On April 24, 2018, $110 $106 $4 • three 38 • development assets which include a project at the Geysers, California; a second As a result of the acquisition, the Company expanded its overall generation capacity and expects to improve the profitability of the purchased assets through cost reduction and synergies. The Company accounted for the transaction in accordance with Accounting Standard Codification ASC 805, 810, may one 2017 01, 2 not The Company deemed the transaction to not not The following table summarizes the purchase price allocation to the fair value of the assets acquired and liabilities assumed (in millions): Cash and cash equivalents and restricted cash $ 37.9 Property, plant and equipment and construction-in-process 77.3 Intangible assets (1) 127.0 Goodwill (2) 19.3 Total assets acquired $ 261.5 Other working capital $ (8.2 ) Deferred tax liability (4.9 ) Long-term term debt (98.3 ) Asset retirement obligation (9.0 ) Noncontrolling interest (34.9 ) Total liabilities assumed $ (155.3 ) Total assets acquired, and liabilities assumed, net $ 106.2 ( 1 Intangible assets are primarily related to long-term electricity power purchase agreements and depreciated over an average of 19 ( 2 Goodwill is primarily related to the expected synergies in operations as a result of the purchase transaction and allocated to the Electricity segment. The fair value of the noncontrolling interest of $34.9 40% 20 9%. Total Electricity segment revenues and operating profit related to the three $7.3 $1.6 three September 30, 2018 $10.7 $2.6 nine September 30, 2018 January 1, 2017: Pro forma for the three months ended September 30, 2018 Pro forma for the three months ended September 30, 2017 Pro forma for the nine months ended September 30, 2018 Pro forma for the nine months ended September 30, 2017 (Dollars in thousands) Electricity revenues $ 116,891 $ 117,688 $ 382,856 $ 359,108 Total revenues 166,480 157,185 540,099 548,007 Operating income 25,902 43,210 115,582 157,609 Migdal Senior Unsecured Loan On March 22, 2018, $100 15 $4.2 September 15, 2021, $37 March 15, 2029. 4.8% The Migdal Loan is subject to early redemption by the Company prior to maturity from time to time (but not 0.50%. 0.25% no 1% 0.25% no 4.8% 4.5, 0.5% The Migdal Loan constitutes senior unsecured indebtedness of the Company and will rank equally in right of payment with any existing and future senior unsecured indebtedness of the Company, and effectively junior to any existing and future secured indebtedness, to the extent of the security therefore. The Migdal Loan Agreement includes various affirmative and negative covenants, including a covenant that the Company maintain (i) a debt to adjusted EBITDA ratio below 6, not $650 not 25%. $800 one not 50% March 27, 2018 September 30, 2018, Other comprehensive income For the nine September 30, 2018 2017, $16,000 $56,000, $22,000 $21,000, $5,000 35,000 three September 30, 2018 2017, $6,000 $2,000, $6,000 9,000 $0 11,000 September 30, 2018 $0.9 Write-offs of unsuccessful exploration activities Write-offs of unsuccessful exploration activities for the three nine September 30, 2018 $0 $0.1 no three nine September 30, 2017. Reconciliation of Cash and cash equivalents and Restricted cash and cash equivalents The following table provides a reconciliation of Cash and cash equivalents and Restricted cash and cash equivalents reported on the balance sheet that sum to the total of the same amounts shown on the statement of cash flows: September 30, December 31, 2018 2017 (Dollars in thousands) Cash and cash equivalents $ 71,965 $ 47,818 Restricted cash and cash equivalents 83,101 48,825 Total Cash and cash equivalents and restricted cash and cash equivalents $ 155,066 $ 96,643 Concentration of credit risk Financial instruments that potentially subject the Company to a concentration of credit risk consist principally of temporary cash investments and accounts receivable. The Company places its temporary cash investments with high credit quality financial institutions located in the United States (“U.S.”) and in foreign countries. At September 30, 2018 December 31, 2017, $20.9 $21.2 ten $250,000 September 30, 2018 December 31, 2017, $76.8 $32.8 At September 30, 2018 December 31, 2017, $92.6 $78.1 September 30, 2018 December 31, 2017, 53% 57% Sierra Pacific Power Company and Nevada Power Company (subsidiaries of NV Energy, Inc.) accounted for 13.6% 16.3% three September 30, 2018 2017, 15.7% 17.4% nine September 30, 2018 2017, Southern California Public Power Authority (“SCPPA”) accounted for 13.7% 9.1% three September 30, 2018 2017, 14.9% 8.9% nine September 30, 2018 2017. Kenya Power and Lighting Co. Ltd. accounted for 18.6% 17.6% three September 30, 2018 2017, 16.7% 15.7% nine September 30, 2018 2017, The Company has historically been able to collect on substantially all of its receivable balances and believes it will continue to be able to collect all amounts due. Accordingly, no

Note 2 - New Accounting Pronoun

Note 2 - New Accounting Pronouncements	9 Months Ended
	Sep. 30, 2018
Notes to Financial Statements
New Accounting Pronouncements and Changes in Accounting Principles [Text Block]	NOTE 2 New accounting pronouncements effective in the nine September 30, 2018 Income Taxes In March 2018, 2018 05, 740 No. 118, 118” December 2017. 11 Revenues from Contracts with Customers In May 2014, 2014 09, 606, 1 2 3 4 5 2014 09 March 2016, 2016 08, not The Company adopted this update effectively as of January 1, 2018 one five 606, The adoption of ASC 606, not 2018, 606 January 1, 2018, (Dollars in millions) Electricity segment revenues $ – Product segment revenues – Other segment revenues – Investment in an unconsolidated company 24.0 Electricity segment revenues July 1, 2003, three 840 606, 30 60 Product segment revenues third not not no one two In contracts for which we determine that control is not Accounting for product contracts that are satisfied over time includes use of several estimates such as variable consideration related to bonuses and penalties and total estimated cost for completing the contract. The estimated amount of variable consideration will be included in the transaction price only to the extent that it is probable that a significant reversal in the amount of cumulative revenue recognized will not The nature of our product contracts give rise to several modifications or change requests by our customers. Substantially all of the modifications are treated as cumulative catch-ups to revenues since the additional goods are not one The Company generally provides a one three nine September 30, 2018 2017. Contract Assets and Liabilities related to our Product segment: Contract assets reflect revenue recognized and performance obligations satisfied in advance of customer billing. Contract liabilities relate to payments received in advance of the satisfaction of performance under the contract. We receive payments from customers based on the terms established in our contracts. Total contract assets and contract liabilities as of September 30, 2018 December 31, 2017 September 30, December 31, 2018 2017 (Dollars in thousands) Contract assets (*) $ 47,811 $ 40,945 Contract liabilities (*) (21,760 ) (20,241 ) Contract assets, net $ 26,051 $ 20,704 (*) Contract assets and contract liabilities are presented as "Costs and estimated earnings in excess of billings on uncompleted contracts" and "Billings in excess of costs and estimated earnings on uncompleted contracts", respectively, on the consolidated balance sheet. The following table presents the significant changes in the contract assets and contract liabilities for the nine September 30, 2018: Contract assets Contract liabilities (Dollars in thousands) Recognition of contract liabilities as revenue as a result of performance obligations satisfied $ - $ 22,504 Cash received in advance for which revenues have not yet recognized, net expenditures made - (29,796 ) Reduction of contract assets as a result of rights to consideration becoming unconditional (87,510 ) - Contract assets recognized, net of recognized receivables 100,150 - Net change in contract assets and contract liabilities 12,640 (7,292 ) The timing of revenue recognition, billings and cash collections results in accounts receivable, contract assets and contract liabilities on the condensed consolidated balance sheet. In our Products segment, amounts are billed as work progresses in accordance with agreed-upon contractual terms, or upon achievement of contractual milestones. Generally, billing occurs subsequent to the recognition of revenue, resulting in contract assets. However, we sometimes receive advances or deposits from our customers before revenue can be recognized, resulting in contract liabilities. These assets and liabilities are reported on the consolidated balance sheet on a contract-by-contract basis at the end of each reporting period. The timing of billing our customers and receiving advance payments vary from contract to contract. We typically receive a down payment of between 10% 20% no On September 30, 2018, $226.4 not 99% 24 The following schedule reconciles revenues accounted for under ASC 840, 606, three nine September 30, 2018: Three Months Ended September 30, 2018 Nine Months Ended September 30, 2018 (Dollars in thousands) (Dollars in thousands) Electricity Revenues accounted under ASC 840, Leases $ 111,114 $ 353,859 Electricity and Product revenues accounted under ASC 606 55,366 174,943 Total consolidated revenues $ 166,480 $ 528,802 Disaggregated revenues from contracts with customers for the three nine September 30, 2018 9 Investment in an unconsolidated company 606 one $24.0 January 1, 2018. not not The following schedule quantifies the impact of adopting ASC 606 three nine September 30, 2018: Three months ended September 30, 2018 under previous standard Effect of the New Revenue Standard As reported for the three months ended September 30, 2018 (Dollars in thousands) Equity in earnings (losses) of investees, net $ (15 ) $ (102 ) $ (117 ) Income from continuing operations 10,209 (102 ) 10,107 Net income attributable to the Company’s stockholders 10,683 (102 ) 10,581 Retained earnings as of the end of the period 410,972 (102 ) 410,870 Nine months ended September 30, 2018 under previous standard Effect of the New Revenue Standard As reported for the nine months ended September 30, 2018 (Dollars in thousands) Equity in earnings (losses) of investees, net $ (1,308 ) $ 2,789 $ 1,481 Income from continuing operations 84,233 2,789 87,022 Net income attributable to the Company’s stockholders 76,957 2,789 79,746 Retained earnings as of the end of the period 408,081 2,789 410,870 Other segment revenues 606 may Compensation - Stock Compensation In May 2017, 2017 09, 718 718. 1 2 3 718 December 15, 2017. not Business Combinations In January 2017, 2017 01, 805 not December 15, 2017, not Statement of Cash Flow In November 2016, 2016 18, 230 December 15, 2017 three March 31, 2018 Intra-Entity Transfers of Assets Other than Inventory In October 2016, 2016 16, not December 15, 2017 three March 31, 2018 $1.8 $49.8 $51.6 Statement of Cash Flows: Classification of Certain Cash Receipts and Cash payments (Topic 230 In August 2016, 2016 15, 230 eight December 15, 2017 $8.0 fourth 2017 Recognition and Measurement of Financial Assets and Financial Liabilities In January 2016, 2016 01, December 15, 2017 not New accounting pronouncements effective in future periods Derivatives and Hedging In August 2017, 2017 12, December 15, 2018, Intangibles –Goodwill and Other In January 2017, 2017 04, 350 not 2 2 first first December 15, 2019. January 1, 2017. Leases In February 2016, 2016 02, 842 two 606. July 2018, 2018 11, December 15, 2018, not Reclassification of Certain Tax Effects from Accumulated Other Comprehensive income In February 2018, 2018 02, 220 2017 December 15, 2018, not

Note 3 - Inventories

Note 3 - Inventories	9 Months Ended
	Sep. 30, 2018
Notes to Financial Statements
Inventory Disclosure [Text Block]	NOTE 3 Inventories consist of the following: September 30, December 31, 2018 2017 (Dollars in thousands) Raw materials and purchased parts for assembly $ 26,604 $ 12,007 Self-manufactured assembly parts and finished products 10,838 7,544 Total $ 37,442 $ 19,551

Note 4 - Investment in an Uncon

Note 4 - Investment in an Unconsolidated Company	9 Months Ended
	Sep. 30, 2018
Notes to Financial Statements
Equity Method Investments and Joint Ventures Disclosure [Text Block]	NOTE 4 Unconsolidated investments consist of the following: September 30, December 31, 2018 2017 (Dollars in thousands) Sarulla $ 67,739 $ 34,084 The Sarulla Project The Company holds a 12.75% 330 three 110 NIL 2, April 2018. April 4, 2013 30 During the three nine September 30, 2018, $0 $3.8 $62.0 The Sarulla consortium entered into interest rate swap agreements with various international banks, effective as of June 4, 2014, Three Months Ended September 30, Nine Months Ended September 30, 2018 2017 2018 2017 (Dollars in thousands) (Dollars in thousands) Change, net of deferred tax, in unrealized gains (losses) in respect of the Company’s share in derivative instruments of unconsolidated investment $ 1,012 $ 618 $ 4,175 $ 271 The related accumulated loss recorded by the Company in other comprehensive income (loss) as of September 30, 2018 $0.9 As further described above under the heading “New accounting pronouncement effective in the nine September 30, 2018” 2 606, January 1, 2018. $24.0 January 1, 2018. not one $24.0 January 1, 2018,

Note 5 - Fair Value of Financia

Note 5 - Fair Value of Financial Instruments	9 Months Ended
	Sep. 30, 2018
Notes to Financial Statements
Fair Value Disclosures [Text Block]	NOTE 5— The fair value measurement guidance clarifies that fair value is an exit price, representing the amount that would be received upon selling an asset or paid upon transferring a liability in an orderly transaction between market participants. As such, fair value is a market-based measurement that should be determined based on assumptions that market participants would use in pricing an asset or liability. The guidance establishes a fair value hierarchy that prioritizes the inputs to valuation techniques used to measure fair value. The hierarchy gives the highest priority to unadjusted quoted prices in active markets for identical assets or liabilities (Level 1 3 three Level 1 Level 2 not Level 3 no The following table sets forth certain fair value information at September 30, 2018 December 31, 2017 September 30, 2018 Fair Value Carrying Value at September 30, 2018 Total Level 1 Level 2 Level 3 (Dollars in thousands) Assets: Current assets: Cash equivalents (including restricted cash accounts) $ 15,941 $ 15,941 $ 15,941 $ — $ — Derivatives: Contingent receivable (1) 105 105 — — 105 Liabilities: Current liabilities: Derivatives: Contingent payables (1) (13,798 ) (13,798 ) — — (13,798 ) Currency forward contracts (2) (210 ) (210 ) — (210 ) — $ 2,038 $ 2,038 $ 15,941 $ (210 ) $ (13,693 ) December 31, 2017 Fair Value Carrying Value at December 31, 2017 Total Level 1 Level 2 Level 3 (Dollars in thousands) Assets Current assets: Cash equivalents (including restricted cash accounts) $ 18,359 $ 18,359 $ 18,359 $ — $ — Derivatives: Contingent receivable (1) 108 108 — — 108 Currency forward contracts (2) 992 992 — 992 — Liabilities: Current liabilities: Derivatives: Contingent payables (1) (13,904 ) (13,904 ) — — (13,904 ) Warrants (1) (3,967 ) (3,967 ) — — (3,967 ) $ 1,588 $ 1,588 $ 18,359 $ 992 $ (17,763 ) ( 1 These amounts relate to contingent receivables and payables and warrants relating to acquisition of substantially all of the assets of Viridity Energy, Inc. and to the Guadeloupe power plant purchase transaction, valued primarily based on unobservable inputs and are included within “Prepaid expenses and other”, “Accounts payable and accrued expenses” and “Other long-term liabilities” on September 30, 2018 2017 ( 2 These amounts relate to currency forward contracts valued primarily based on observable inputs, including forward and spot prices for currencies, net of contracted rates and then multiplied by notional amounts, and are included within “Prepaid expenses and other” and “Accounts payable and accrued expenses”, as applicable, on September 30, 2018 December 31, 2017, The amounts set forth in the tables above include investments in debt instruments and money market funds (which are included in cash equivalents). Those securities and deposits are classified within Level 1 The following table presents the amounts of gain (loss) recognized in the consolidated statements of operations and comprehensive income on derivative instruments not Amount of recognized gain (loss) Derivatives not designated as Location of recognized gain Three Months Ended September 30, Nine Months Ended September 30, hedging instruments (loss) 2018 2017 2018 2017 Put options on natural gas price Derivatives and foreign currency transaction gains (losses) — (121 ) — (362 ) Contingent considerations Derivative and foreign currency transaction gains (losses) — (19 ) — (114 ) Currency forward contracts Derivative and foreign currency and transaction gains (losses) (198 ) (887 ) (1,655 ) 2,832 $ (198 ) $ (1,027 ) $ (1,655 ) $ 2,356 In January 2017, 4.1 $3 January 26, 2017 November 27, 2017 $0.7 The foregoing future and forward transactions were not There were no 1, 2 3 nine September 30, 2018. The fair value of the Company’s long-term debt approximates its carrying amount, except for the following: Fair Value Carrying Amount September 30, 2018 December 31, 2017 September 30, 2018 December 31, 2017 (Dollars in millions) (Dollars in millions) Olkaria III Loan - OPIC 214.2 234.6 215.1 228.6 Olkaria IV Loan - DEG 2 50.1 50.7 50.0 50.0 Amatitlan Loan 30.8 32.8 30.6 33.3 Senior Secured Notes: OrCal Geothermal Inc. ("OrCal") 24.7 34.2 24.0 32.1 OFC 2 LLC ("OFC 2") 215.9 234.6 221.8 232.5 Don A. Campbell 1 ("DAC 1") 79.0 85.5 84.7 88.3 USG Prudential - NV 29.4 — 28.2 — USG Prudential - ID 18.7 — 18.9 — USG DOE 47.2 — 51.4 — Senior Unsecured Bonds 195.7 200.3 204.3 204.3 Senior Unsecured Loan 99.7 — 100.0 — Other long-term debt 5.4 7.0 6.4 7.9 The fair value of the long-term debt is determined by a valuation model, which is based on a conventional discounted cash flow methodology and utilizes assumptions of current borrowing rates. The fair value of revolving lines of credit is determined using a comparison of market-based price sources that are reflective of similar credit ratings to those of the Company. The carrying value of financial instruments such as revolving lines of credit and deposits approximates fair value. The following table presents the fair value of financial instruments as of September 30, 2018: Level 1 Level 2 Level 3 Total (Dollars in millions) Olkaria III - OPIC — — 214.2 214.2 Olkaria IV - DEG 2 — — 50.1 50.1 Amatitlan Loan — 30.8 — 30.8 Senior Secured Notes: OrCal Senior Secured Notes — — 24.7 24.7 OFC 2 Senior Secured Notes — — 215.9 215.9 DAC 1 Senior Secured Notes — — 79.0 79.0 USG Prudential - NV — — 29.4 29.4 USG Prudential - ID — — 18.7 18.7 USG DOE — — 47.2 47.2 Senior Unsecured Bonds — — 195.7 195.7 Senior Unsecured Loan — — 99.7 99.7 Other long-term debt — — 5.4 5.4 Revolving lines of credit — 209.5 — 209.5 Deposits 14.2 — — 14.2 The following table presents the fair value of financial instruments as of December 31, 2017: Level 1 Level 2 Level 3 Total (Dollars in millions) Olkaria III Loan - OPIC $ — $ — $ 234.6 $ 234.6 Olkaria IV - DEG 2 50.7 50.7 Amatitlan Loan — 32.8 — 32.8 Senior Secured Notes: OFC Senior Secured Notes — — — — OrCal Senior Secured Notes — — 34.2 34.2 OFC 2 Senior Secured Notes — — 234.6 234.6 DAC 1 Senior Secured Notes — — 85.5 85.5 Senior Unsecured Bonds — — 200.3 200.3 Other long-term debt — — 7.0 7.0 Revolving lines of credit — 51.5 — 51.5 Deposits 15.6 — — 15.6

Note 6 - Stock-based Compensati

Note 6 - Stock-based Compensation	9 Months Ended
	Sep. 30, 2018
Notes to Financial Statements
Disclosure of Compensation Related Costs, Share-based Payments [Text Block]	NOTE 6 The 2012 In May 2012, 2012 2012 4,000,000 2012 25% 24 25% 36 50% 48 2012 one 100% first 25% third fourth six ten 2012 2012 May 2018 2018 “2018 2012 The 2018 On May 7, 2018, 2018 2018 2018 2018 5,000,000 2018 50% second 25% third fourth 2018 100% first six ten 2018 On May 8, 2018, 295,671 40,489 one 2018 $55.16, five 100% 22% first second 28% third fourth The fair value of each SAR for the director and the CEO on the grant date was $14.56 $14.57, $54.92 $54.23, Risk-free interest rate 2.84 % Expected life (in years) 5.5 Dividend yield 0.79 % Expected volatility 25.24 % Forfeiture rate 0.0 % Sub-Optimal Exercise Factor 2.5 On June 25, 2018, 838,117 19,848 2018 $53.44, six 50% second 25% third fourth The fair value of each SAR for the employees and members of senior management on the grant date was $13.82 $14.64, $52.03 $52.09, Risk-free interest rate 2.79 % Expected life (in years) 6 Dividend yield 0.92 % Expected volatility 25.64 % Forfeiture rate for employees 2.78 % Forfeiture rate for members of the senior management 0.0 % Sub-Optimal Exercise Factor for employees 2.0 Sub-Optimal Exercise Factor for members of the senior management 2.8

Note 7 - Interest Expense, Net

Note 7 - Interest Expense, Net	9 Months Ended
	Sep. 30, 2018
Notes to Financial Statements
Interest Expense Disclosure [Text Block]	NOTE 7 The components of interest expense are as follows: Three Months Ended September 30, Nine Months Ended September 30, 2018 2017 2018 2017 Interest related to sale of tax benefits $ 2,916 $ 1,607 $ 6,086 $ 5,468 Interest expense 16,571 13,299 45,298 41,620 Less — amount capitalized (787 ) (3,214 ) (2,494 ) (5,933 ) $ 18,700 $ 11,692 $ 48,890 $ 41,155

Note 8 - Earnings Per Share

Note 8 - Earnings Per Share	9 Months Ended
	Sep. 30, 2018
Notes to Financial Statements
Earnings Per Share [Text Block]	NOTE 8 Basic earnings per share attributable to the Company’s stockholders is computed by dividing net income or loss attributable to the Company’s stockholders by the weighted average number of shares of common stock outstanding for the period. The Company does not The table below shows the reconciliation of the number of shares used in the computation of basic and diluted earnings per share (in thousands): Three Months Ended September 30, Nine Months Ended September 30, 2018 2017 2018 2017 Weighted average number of shares used in computation of basic earnings per share 50,645 50,367 50,627 49,942 Add: Additional shares from the assumed exercise of employee stock options 318 500 358 727 Weighted average number of shares used in computation of diluted earnings per share 50,963 50,867 50,985 50,669 The number of stock-based awards that could potentially dilute future earnings per share and that were not 388,193 8,851 three September 30, 2018 2017, 205,990 6,494 nine September 30, 2018 2017,

Note 9 - Business Segments

Note 9 - Business Segments	9 Months Ended
	Sep. 30, 2018
Notes to Financial Statements
Segment Reporting Disclosure [Text Block]	NOTE 9 In 2018, 280, 2018 three Transfer prices between the operating segments are determined based on current market values or cost-plus markup of the seller’s business segment. Summarized financial information concerning the Company’s reportable segments is shown in the following tables, including, as further described under Note 1 606: Electricity Product Other Consolidated (Dollars in thousands) Three Months Ended September 30, 2018: Revenues from external customers: United States (1) $ 64,905 $ 281 $ 1,150 $ 66,336 Foreign (2) 51,986 48,158 — 100,144 Net revenue from external customers 116,891 48,439 1,150 166,480 Intersegment revenue — 9,236 — 9,236 Segment assets at period end (3) (*) 2,859,354 125,881 74,348 3,059,583 * Including unconsolidated investments 67,739 — — 67,739 Three Months Ended September 30, 2017: Net revenue from external customers $ 110,876 $ 44,912 1,397 157,185 Intersegment revenue — 28,248 — 28,248 Operating income 37,279 7,765 (1,074 ) 43,970 Segment assets at period end (3) (*) 2,319,083 131,883 52,772 2,503,738 * Including unconsolidated investments 25,367 — — 25,367 Nine Months Ended September 30, 2018: Revenues from external customers: United States (1) $ 221,727 $ 502 $ 5,217 $ 227,446 Foreign (2) 149,832 151,524 — 301,356 Net revenues from external customers 371,559 152,026 5,217 528,802 Intersegment revenues — 45,516 — 45,516 Operating income 94,024 27,614 (4,510 ) 117,128 Segment assets at period end (3) (*) 2,859,354 125,881 74,348 3,059,583 * Including unconsolidated investments 67,739 — — 67,739 Nine Months Ended September 30, 2017: Net revenues from external customers $ 337,548 $ 186,621 $ 2,278 $ 526,447 Intersegment revenues — 61,026 — 61,026 Operating income 116,191 43,398 (2,971 ) 156,618 Segment assets at period end (3) (*) 2,319,083 131,883 52,772 2,503,738 * Including unconsolidated investments 25,367 — — 25,367 ( 1 ) Electricity segment revenues in the United States are all accounted under ASC 840, $5.8 $17.7 three nine September 30, 2018 606 2018. 606, 2 ( 2 ) Electricity segment revenues in foreign countries are all accounted under ASC 840, 606 2 ( 3 ) Electricity segment assets include goodwill in the amount of $26.7 $6.8 September 30, 2018 2017, $13.5 September 30, 2018 2017. Reconciling information between reportable segments and the Company’s consolidated totals is shown in the following table: Three Months Ended September 30, Nine Months Ended September 30, 2018 2017 2018 2017 Revenue: Total segment revenue $ 166,480 $ 157,185 $ 528,802 $ 526,447 Intersegment revenue 9,236 28,248 45,516 61,026 Elimination of intersegment revenue (9,236 ) (28,248 ) (45,516 ) (61,026 ) Total consolidated revenue $ 166,480 $ 157,185 $ 528,802 $ 526,447 Operating income: Operating income $ 25,902 $ 43,970 $ 117,128 $ 156,618 Interest income 214 255 516 861 Interest expense, net (18,700 ) (11,692 ) (48,890 ) (41,155 ) Derivatives and foreign currency transaction gains (losses) (383 ) (1,001 ) (2,511 ) 2,040 Income attributable to sale of tax benefits 4,066 3,506 14,983 14,019 Other non-operating income (expense), net 309 (1,592 ) 7,662 (1,678 ) Total consolidated income before income taxes and equity in income of investees $ 11,408 $ 33,446 $ 88,888 $ 130,705

Note 10 - Commitments and Conti

Note 10 - Commitments and Contingencies	9 Months Ended
	Sep. 30, 2018
Notes to Financial Statements
Commitments and Contingencies Disclosure [Text Block]	NOTE 10 ● On September 11, 2018, October 22, 2018, four 14 2018 ● Following the announcement of the Company’s acquisition of U.S. Geothermal Inc. (“USG”), a number of putative shareholder class action complaints were initially filed on behalf of USG shareholders between March 8, 2018 March 30, 2018 No. 2018 0177 Mar. 12, 2018). May 24, 2018 ● On June 11, 2018, August 8, 2017 May 15, 2018 10 10b 5 20 10 December 31, 2016 2017, 10 nine September 30, 2017 four not ● On May 21, 2018, 11 August 3, 2017 May 13, 2018". 31 1 38C 1 2017 2 May 16, 2018, May 11, 2018 2017 ● On February 18, 2018, January 16, 2018 2 January 2018 3 ● On August 5, 2016, December 12, 2016, August 2014. June 14, 2017, March 25, 2017 two third ● On March 29, 2016, 27th $4.6 3.75% 10 11th ● Jon Olson and Hilary Wilt, together with Puna Pono Alliance filed a complaint on February 17, 2015 16 May 17, 2015, October 10, 2016, January 23, 2017, April 20, 2017 In addition, from time to time, the Company is named as a party to various other lawsuits, claims and other legal and regulatory proceedings that arise in the ordinary course of our business. These actions typically seek, among other things, compensation for alleged personal injury, breach of contract, property damage, punitive damages, civil penalties or other losses, or injunctive or declaratory relief. With respect to such lawsuits, claims and proceedings, the Company accrues reserves when a loss is probable, and the amount of such loss can be reasonably estimated. It is the opinion of the Company’s management that the outcome of these proceedings, individually and collectively, will not

Note 11 - Income Taxes

Note 11 - Income Taxes	9 Months Ended
	Sep. 30, 2018
Notes to Financial Statements
Income Tax Disclosure [Text Block]	NOTE 11 The Company’s effective tax rate expense (benefit) for the three September 30, 2018 2017 10.4% 18.6%, 3.8% 38.2% nine September 30, 2018 2017, 21% nine September 30, 2018 37.5% 16% The Tax Cuts and Jobs Act (the “Tax Act”) was enacted on December 22, 2017. 1 35 21 2 3 4 5 6 7 8 December 31, 2017. The SEC staff issued SAB 118, 118 not one 740. 118, 740 740 The Company is applying the guidance in SAB 118 December 31, 2017, 1 2 3 4 September 30, 2018, December 31, 2017, The Company continues to analyze specific provisions of the Act, including the newly created requirement that GILTI earned by controlled foreign corporations (CFCs) must be included currently in gross income of the CFC’s U.S. shareholder. In the second 2018, March 31, 2018 $27.5 $44.4 March 31, 2018. The U.S. Department of the Treasury and the IRS recently published proposed regulations under IRC Section 965 $29.8 2017, December 22, 2017.

Note 12 - Subsequent Events

Note 12 - Subsequent Events	9 Months Ended
	Sep. 30, 2018
Notes to Financial Statements
Subsequent Events [Text Block]	NOTE 12 Cash dividend On November 6, 2018, $5.1 $0.10 November 20, 2018, December 4, 2018. Stock based awards On November 7, 2018, 15,395 17,338 2018 November 7, 2018. $120,000 $180,000. six first $14.8. $52.6. Platanares finance agreement On October 31, 2018, 35 $124.7 $114.7 second $10 first 2019. 7.02% 14

Significant Accounting Policies

Significant Accounting Policies (Policies)	9 Months Ended
	Sep. 30, 2018
Accounting Policies [Abstract]
Debt, Policy [Policy Text Block]	Migdal Senior Unsecured Loan On March 22, 2018, $100 15 $4.2 September 15, 2021, $37 March 15, 2029. 4.8% The Migdal Loan is subject to early redemption by the Company prior to maturity from time to time (but not 0.50%. 0.25% no 1% 0.25% no 4.8% 4.5, 0.5% The Migdal Loan constitutes senior unsecured indebtedness of the Company and will rank equally in right of payment with any existing and future senior unsecured indebtedness of the Company, and effectively junior to any existing and future secured indebtedness, to the extent of the security therefore. The Migdal Loan Agreement includes various affirmative and negative covenants, including a covenant that the Company maintain (i) a debt to adjusted EBITDA ratio below 6, not $650 not 25%. $800 one not 50% March 27, 2018 September 30, 2018,
Comprehensive Income, Policy [Policy Text Block]	Other comprehensive income For the nine September 30, 2018 2017, $16,000 $56,000, $22,000 $21,000, $5,000 35,000 three September 30, 2018 2017, $6,000 $2,000, $6,000 9,000 $0 11,000 September 30, 2018 $0.9
Exploratory Drilling Costs Capitalization and Impairment, Policy [Policy Text Block]	Write-offs of unsuccessful exploration activities Write-offs of unsuccessful exploration activities for the three nine September 30, 2018 $0 $0.1 no three nine September 30, 2017.
Cash and Cash Equivalents, Policy [Policy Text Block]	Reconciliation of Cash and cash equivalents and Restricted cash and cash equivalents The following table provides a reconciliation of Cash and cash equivalents and Restricted cash and cash equivalents reported on the balance sheet that sum to the total of the same amounts shown on the statement of cash flows: September 30, December 31, 2018 2017 (Dollars in thousands) Cash and cash equivalents $ 71,965 $ 47,818 Restricted cash and cash equivalents 83,101 48,825 Total Cash and cash equivalents and restricted cash and cash equivalents $ 155,066 $ 96,643
Concentration Risk, Credit Risk, Policy [Policy Text Block]	Concentration of credit risk Financial instruments that potentially subject the Company to a concentration of credit risk consist principally of temporary cash investments and accounts receivable. The Company places its temporary cash investments with high credit quality financial institutions located in the United States (“U.S.”) and in foreign countries. At September 30, 2018 December 31, 2017, $20.9 $21.2 ten $250,000 September 30, 2018 December 31, 2017, $76.8 $32.8 At September 30, 2018 December 31, 2017, $92.6 $78.1 September 30, 2018 December 31, 2017, 53% 57% Sierra Pacific Power Company and Nevada Power Company (subsidiaries of NV Energy, Inc.) accounted for 13.6% 16.3% three September 30, 2018 2017, 15.7% 17.4% nine September 30, 2018 2017, Southern California Public Power Authority (“SCPPA”) accounted for 13.7% 9.1% three September 30, 2018 2017, 14.9% 8.9% nine September 30, 2018 2017. Kenya Power and Lighting Co. Ltd. accounted for 18.6% 17.6% three September 30, 2018 2017, 16.7% 15.7% nine September 30, 2018 2017, The Company has historically been able to collect on substantially all of its receivable balances and believes it will continue to be able to collect all amounts due. Accordingly, no
New Accounting Pronouncements, Policy [Policy Text Block]	New accounting pronouncements effective in the nine September 30, 2018 Income Taxes In March 2018, 2018 05, 740 No. 118, 118” December 2017. 11 Revenues from Contracts with Customers In May 2014, 2014 09, 606, 1 2 3 4 5 2014 09 March 2016, 2016 08, not The Company adopted this update effectively as of January 1, 2018 one five 606, The adoption of ASC 606, not 2018, 606 January 1, 2018, (Dollars in millions) Electricity segment revenues $ – Product segment revenues – Other segment revenues – Investment in an unconsolidated company 24.0 Electricity segment revenues July 1, 2003, three 840 606, 30 60 Product segment revenues third not not no one two In contracts for which we determine that control is not Accounting for product contracts that are satisfied over time includes use of several estimates such as variable consideration related to bonuses and penalties and total estimated cost for completing the contract. The estimated amount of variable consideration will be included in the transaction price only to the extent that it is probable that a significant reversal in the amount of cumulative revenue recognized will not The nature of our product contracts give rise to several modifications or change requests by our customers. Substantially all of the modifications are treated as cumulative catch-ups to revenues since the additional goods are not one The Company generally provides a one three nine September 30, 2018 2017. Contract Assets and Liabilities related to our Product segment: Contract assets reflect revenue recognized and performance obligations satisfied in advance of customer billing. Contract liabilities relate to payments received in advance of the satisfaction of performance under the contract. We receive payments from customers based on the terms established in our contracts. Total contract assets and contract liabilities as of September 30, 2018 December 31, 2017 September 30, December 31, 2018 2017 (Dollars in thousands) Contract assets (*) $ 47,811 $ 40,945 Contract liabilities (*) (21,760 ) (20,241 ) Contract assets, net $ 26,051 $ 20,704 (*) Contract assets and contract liabilities are presented as "Costs and estimated earnings in excess of billings on uncompleted contracts" and "Billings in excess of costs and estimated earnings on uncompleted contracts", respectively, on the consolidated balance sheet. The following table presents the significant changes in the contract assets and contract liabilities for the nine September 30, 2018: Contract assets Contract liabilities (Dollars in thousands) Recognition of contract liabilities as revenue as a result of performance obligations satisfied $ - $ 22,504 Cash received in advance for which revenues have not yet recognized, net expenditures made - (29,796 ) Reduction of contract assets as a result of rights to consideration becoming unconditional (87,510 ) - Contract assets recognized, net of recognized receivables 100,150 - Net change in contract assets and contract liabilities 12,640 (7,292 ) The timing of revenue recognition, billings and cash collections results in accounts receivable, contract assets and contract liabilities on the condensed consolidated balance sheet. In our Products segment, amounts are billed as work progresses in accordance with agreed-upon contractual terms, or upon achievement of contractual milestones. Generally, billing occurs subsequent to the recognition of revenue, resulting in contract assets. However, we sometimes receive advances or deposits from our customers before revenue can be recognized, resulting in contract liabilities. These assets and liabilities are reported on the consolidated balance sheet on a contract-by-contract basis at the end of each reporting period. The timing of billing our customers and receiving advance payments vary from contract to contract. We typically receive a down payment of between 10% 20% no On September 30, 2018, $226.4 not 99% 24 The following schedule reconciles revenues accounted for under ASC 840, 606, three nine September 30, 2018: Three Months Ended September 30, 2018 Nine Months Ended September 30, 2018 (Dollars in thousands) (Dollars in thousands) Electricity Revenues accounted under ASC 840, Leases $ 111,114 $ 353,859 Electricity and Product revenues accounted under ASC 606 55,366 174,943 Total consolidated revenues $ 166,480 $ 528,802 Disaggregated revenues from contracts with customers for the three nine September 30, 2018 9 Investment in an unconsolidated company 606 one $24.0 January 1, 2018. not not The following schedule quantifies the impact of adopting ASC 606 three nine September 30, 2018: Three months ended September 30, 2018 under previous standard Effect of the New Revenue Standard As reported for the three months ended September 30, 2018 (Dollars in thousands) Equity in earnings (losses) of investees, net $ (15 ) $ (102 ) $ (117 ) Income from continuing operations 10,209 (102 ) 10,107 Net income attributable to the Company’s stockholders 10,683 (102 ) 10,581 Retained earnings as of the end of the period 410,972 (102 ) 410,870 Nine months ended September 30, 2018 under previous standard Effect of the New Revenue Standard As reported for the nine months ended September 30, 2018 (Dollars in thousands) Equity in earnings (losses) of investees, net $ (1,308 ) $ 2,789 $ 1,481 Income from continuing operations 84,233 2,789 87,022 Net income attributable to the Company’s stockholders 76,957 2,789 79,746 Retained earnings as of the end of the period 408,081 2,789 410,870 Other segment revenues 606 may Compensation - Stock Compensation In May 2017, 2017 09, 718 718. 1 2 3 718 December 15, 2017. not Business Combinations In January 2017, 2017 01, 805 not December 15, 2017, not Statement of Cash Flow In November 2016, 2016 18, 230 December 15, 2017 three March 31, 2018 Intra-Entity Transfers of Assets Other than Inventory In October 2016, 2016 16, not December 15, 2017 three March 31, 2018 $1.8 $49.8 $51.6 Statement of Cash Flows: Classification of Certain Cash Receipts and Cash payments (Topic 230 In August 2016, 2016 15, 230 eight December 15, 2017 $8.0 fourth 2017 Recognition and Measurement of Financial Assets and Financial Liabilities In January 2016, 2016 01, December 15, 2017 not New accounting pronouncements effective in future periods Derivatives and Hedging In August 2017, 2017 12, December 15, 2018, Intangibles –Goodwill and Other In January 2017, 2017 04, 350 not 2 2 first first December 15, 2019. January 1, 2017. Leases In February 2016, 2016 02, 842 two 606. July 2018, 2018 11, December 15, 2018, not Reclassification of Certain Tax Effects from Accumulated Other Comprehensive income In February 2018, 2018 02, 220 2017 December 15, 2018, not

Note 1 - General and Basis of_2

Note 1 - General and Basis of Presentation (Tables)	9 Months Ended
	Sep. 30, 2018
Notes Tables
Schedule of Recognized Identified Assets Acquired and Liabilities Assumed [Table Text Block]	Cash and cash equivalents and restricted cash $ 37.9 Property, plant and equipment and construction-in-process 77.3 Intangible assets (1) 127.0 Goodwill (2) 19.3 Total assets acquired $ 261.5 Other working capital $ (8.2 ) Deferred tax liability (4.9 ) Long-term term debt (98.3 ) Asset retirement obligation (9.0 ) Noncontrolling interest (34.9 ) Total liabilities assumed $ (155.3 ) Total assets acquired, and liabilities assumed, net $ 106.2
Business Acquisition, Pro Forma Information [Table Text Block]	Pro forma for the three months ended September 30, 2018 Pro forma for the three months ended September 30, 2017 Pro forma for the nine months ended September 30, 2018 Pro forma for the nine months ended September 30, 2017 (Dollars in thousands) Electricity revenues $ 116,891 $ 117,688 $ 382,856 $ 359,108 Total revenues 166,480 157,185 540,099 548,007 Operating income 25,902 43,210 115,582 157,609
Schedule of Cash and Cash Equivalents [Table Text Block]	September 30, December 31, 2018 2017 (Dollars in thousands) Cash and cash equivalents $ 71,965 $ 47,818 Restricted cash and cash equivalents 83,101 48,825 Total Cash and cash equivalents and restricted cash and cash equivalents $ 155,066 $ 96,643

Note 2 - New Accounting Prono_2

Note 2 - New Accounting Pronouncements (Tables)	9 Months Ended
	Sep. 30, 2018
Notes Tables
Schedule of New Accounting Pronouncements and Changes in Accounting Principles [Table Text Block]	(Dollars in millions) Electricity segment revenues $ – Product segment revenues – Other segment revenues – Investment in an unconsolidated company 24.0 Three Months Ended September 30, 2018 Nine Months Ended September 30, 2018 (Dollars in thousands) (Dollars in thousands) Electricity Revenues accounted under ASC 840, Leases $ 111,114 $ 353,859 Electricity and Product revenues accounted under ASC 606 55,366 174,943 Total consolidated revenues $ 166,480 $ 528,802 Three months ended September 30, 2018 under previous standard Effect of the New Revenue Standard As reported for the three months ended September 30, 2018 (Dollars in thousands) Equity in earnings (losses) of investees, net $ (15 ) $ (102 ) $ (117 ) Income from continuing operations 10,209 (102 ) 10,107 Net income attributable to the Company’s stockholders 10,683 (102 ) 10,581 Retained earnings as of the end of the period 410,972 (102 ) 410,870 Nine months ended September 30, 2018 under previous standard Effect of the New Revenue Standard As reported for the nine months ended September 30, 2018 (Dollars in thousands) Equity in earnings (losses) of investees, net $ (1,308 ) $ 2,789 $ 1,481 Income from continuing operations 84,233 2,789 87,022 Net income attributable to the Company’s stockholders 76,957 2,789 79,746 Retained earnings as of the end of the period 408,081 2,789 410,870
Contract with Customer, Asset and Liability [Table Text Block]	September 30, December 31, 2018 2017 (Dollars in thousands) Contract assets (*) $ 47,811 $ 40,945 Contract liabilities (*) (21,760 ) (20,241 ) Contract assets, net $ 26,051 $ 20,704 Contract assets Contract liabilities (Dollars in thousands) Recognition of contract liabilities as revenue as a result of performance obligations satisfied $ - $ 22,504 Cash received in advance for which revenues have not yet recognized, net expenditures made - (29,796 ) Reduction of contract assets as a result of rights to consideration becoming unconditional (87,510 ) - Contract assets recognized, net of recognized receivables 100,150 - Net change in contract assets and contract liabilities 12,640 (7,292 )

Note 3 - Inventories (Tables)

Note 3 - Inventories (Tables)	9 Months Ended
	Sep. 30, 2018
Notes Tables
Schedule of Inventory, Current [Table Text Block]	September 30, December 31, 2018 2017 (Dollars in thousands) Raw materials and purchased parts for assembly $ 26,604 $ 12,007 Self-manufactured assembly parts and finished products 10,838 7,544 Total $ 37,442 $ 19,551

Note 4 - Investment in an Unc_2

Note 4 - Investment in an Unconsolidated Company (Tables)	9 Months Ended
	Sep. 30, 2018
Notes Tables
Equity Method Investments [Table Text Block]	September 30, December 31, 2018 2017 (Dollars in thousands) Sarulla $ 67,739 $ 34,084
Other Comprehensive Income (Loss) from Equity Method Investments[Table Text Block]	Three Months Ended September 30, Nine Months Ended September 30, 2018 2017 2018 2017 (Dollars in thousands) (Dollars in thousands) Change, net of deferred tax, in unrealized gains (losses) in respect of the Company’s share in derivative instruments of unconsolidated investment $ 1,012 $ 618 $ 4,175 $ 271

Note 5 - Fair Value of Financ_2

Note 5 - Fair Value of Financial Instruments (Tables)	9 Months Ended
	Sep. 30, 2018
Notes Tables
Fair Value, by Balance Sheet Grouping [Table Text Block]	September 30, 2018 Fair Value Carrying Value at September 30, 2018 Total Level 1 Level 2 Level 3 (Dollars in thousands) Assets: Current assets: Cash equivalents (including restricted cash accounts) $ 15,941 $ 15,941 $ 15,941 $ — $ — Derivatives: Contingent receivable (1) 105 105 — — 105 Liabilities: Current liabilities: Derivatives: Contingent payables (1) (13,798 ) (13,798 ) — — (13,798 ) Currency forward contracts (2) (210 ) (210 ) — (210 ) — $ 2,038 $ 2,038 $ 15,941 $ (210 ) $ (13,693 ) December 31, 2017 Fair Value Carrying Value at December 31, 2017 Total Level 1 Level 2 Level 3 (Dollars in thousands) Assets Current assets: Cash equivalents (including restricted cash accounts) $ 18,359 $ 18,359 $ 18,359 $ — $ — Derivatives: Contingent receivable (1) 108 108 — — 108 Currency forward contracts (2) 992 992 — 992 — Liabilities: Current liabilities: Derivatives: Contingent payables (1) (13,904 ) (13,904 ) — — (13,904 ) Warrants (1) (3,967 ) (3,967 ) — — (3,967 ) $ 1,588 $ 1,588 $ 18,359 $ 992 $ (17,763 )
Derivative Instruments, Gain (Loss) [Table Text Block]	Amount of recognized gain (loss) Derivatives not designated as Location of recognized gain Three Months Ended September 30, Nine Months Ended September 30, hedging instruments (loss) 2018 2017 2018 2017 Put options on natural gas price Derivatives and foreign currency transaction gains (losses) — (121 ) — (362 ) Contingent considerations Derivative and foreign currency transaction gains (losses) — (19 ) — (114 ) Currency forward contracts Derivative and foreign currency and transaction gains (losses) (198 ) (887 ) (1,655 ) 2,832 $ (198 ) $ (1,027 ) $ (1,655 ) $ 2,356
Schedule of Carrying Values and Estimated Fair Values of Debt Instruments [Table Text Block]	Fair Value Carrying Amount September 30, 2018 December 31, 2017 September 30, 2018 December 31, 2017 (Dollars in millions) (Dollars in millions) Olkaria III Loan - OPIC 214.2 234.6 215.1 228.6 Olkaria IV Loan - DEG 2 50.1 50.7 50.0 50.0 Amatitlan Loan 30.8 32.8 30.6 33.3 Senior Secured Notes: OrCal Geothermal Inc. ("OrCal") 24.7 34.2 24.0 32.1 OFC 2 LLC ("OFC 2") 215.9 234.6 221.8 232.5 Don A. Campbell 1 ("DAC 1") 79.0 85.5 84.7 88.3 USG Prudential - NV 29.4 — 28.2 — USG Prudential - ID 18.7 — 18.9 — USG DOE 47.2 — 51.4 — Senior Unsecured Bonds 195.7 200.3 204.3 204.3 Senior Unsecured Loan 99.7 — 100.0 — Other long-term debt 5.4 7.0 6.4 7.9
Fair Value, Liabilities Measured on Recurring and Nonrecurring Basis [Table Text Block]	Level 1 Level 2 Level 3 Total (Dollars in millions) Olkaria III - OPIC — — 214.2 214.2 Olkaria IV - DEG 2 — — 50.1 50.1 Amatitlan Loan — 30.8 — 30.8 Senior Secured Notes: OrCal Senior Secured Notes — — 24.7 24.7 OFC 2 Senior Secured Notes — — 215.9 215.9 DAC 1 Senior Secured Notes — — 79.0 79.0 USG Prudential - NV — — 29.4 29.4 USG Prudential - ID — — 18.7 18.7 USG DOE — — 47.2 47.2 Senior Unsecured Bonds — — 195.7 195.7 Senior Unsecured Loan — — 99.7 99.7 Other long-term debt — — 5.4 5.4 Revolving lines of credit — 209.5 — 209.5 Deposits 14.2 — — 14.2 Level 1 Level 2 Level 3 Total (Dollars in millions) Olkaria III Loan - OPIC $ — $ — $ 234.6 $ 234.6 Olkaria IV - DEG 2 50.7 50.7 Amatitlan Loan — 32.8 — 32.8 Senior Secured Notes: OFC Senior Secured Notes — — — — OrCal Senior Secured Notes — — 34.2 34.2 OFC 2 Senior Secured Notes — — 234.6 234.6 DAC 1 Senior Secured Notes — — 85.5 85.5 Senior Unsecured Bonds — — 200.3 200.3 Other long-term debt — — 7.0 7.0 Revolving lines of credit — 51.5 — 51.5 Deposits 15.6 — — 15.6

Note 6 - Stock-based Compensa_2

Note 6 - Stock-based Compensation (Tables)	9 Months Ended
	Sep. 30, 2018
Notes Tables
Schedule of Share-based Payment Award, Equity Awards Other than Options, Valuation Assumptions [Table Text Block]	Risk-free interest rate 2.84 % Expected life (in years) 5.5 Dividend yield 0.79 % Expected volatility 25.24 % Forfeiture rate 0.0 % Sub-Optimal Exercise Factor 2.5 Risk-free interest rate 2.79 % Expected life (in years) 6 Dividend yield 0.92 % Expected volatility 25.64 % Forfeiture rate for employees 2.78 % Forfeiture rate for members of the senior management 0.0 % Sub-Optimal Exercise Factor for employees 2.0 Sub-Optimal Exercise Factor for members of the senior management 2.8

Note 7 - Interest Expense, Net

Note 7 - Interest Expense, Net (Tables)	9 Months Ended
	Sep. 30, 2018
Notes Tables
Schedule of Other Nonoperating Expense, by Component [Table Text Block]	Three Months Ended September 30, Nine Months Ended September 30, 2018 2017 2018 2017 Interest related to sale of tax benefits $ 2,916 $ 1,607 $ 6,086 $ 5,468 Interest expense 16,571 13,299 45,298 41,620 Less — amount capitalized (787 ) (3,214 ) (2,494 ) (5,933 ) $ 18,700 $ 11,692 $ 48,890 $ 41,155

Note 8 - Earnings Per Share (Ta

Note 8 - Earnings Per Share (Tables)	9 Months Ended
	Sep. 30, 2018
Notes Tables
Schedule of Weighted Average Number of Shares [Table Text Block]	Three Months Ended September 30, Nine Months Ended September 30, 2018 2017 2018 2017 Weighted average number of shares used in computation of basic earnings per share 50,645 50,367 50,627 49,942 Add: Additional shares from the assumed exercise of employee stock options 318 500 358 727 Weighted average number of shares used in computation of diluted earnings per share 50,963 50,867 50,985 50,669

Note 9 - Business Segments (Tab

Note 9 - Business Segments (Tables)	9 Months Ended
	Sep. 30, 2018
Notes Tables
Schedule of Segment Reporting Information, by Segment [Table Text Block]	Electricity Product Other Consolidated (Dollars in thousands) Three Months Ended September 30, 2018: Revenues from external customers: United States (1) $ 64,905 $ 281 $ 1,150 $ 66,336 Foreign (2) 51,986 48,158 — 100,144 Net revenue from external customers 116,891 48,439 1,150 166,480 Intersegment revenue — 9,236 — 9,236 Segment assets at period end (3) (*) 2,859,354 125,881 74,348 3,059,583 * Including unconsolidated investments 67,739 — — 67,739 Three Months Ended September 30, 2017: Net revenue from external customers $ 110,876 $ 44,912 1,397 157,185 Intersegment revenue — 28,248 — 28,248 Operating income 37,279 7,765 (1,074 ) 43,970 Segment assets at period end (3) (*) 2,319,083 131,883 52,772 2,503,738 * Including unconsolidated investments 25,367 — — 25,367 Nine Months Ended September 30, 2018: Revenues from external customers: United States (1) $ 221,727 $ 502 $ 5,217 $ 227,446 Foreign (2) 149,832 151,524 — 301,356 Net revenues from external customers 371,559 152,026 5,217 528,802 Intersegment revenues — 45,516 — 45,516 Operating income 94,024 27,614 (4,510 ) 117,128 Segment assets at period end (3) (*) 2,859,354 125,881 74,348 3,059,583 * Including unconsolidated investments 67,739 — — 67,739 Nine Months Ended September 30, 2017: Net revenues from external customers $ 337,548 $ 186,621 $ 2,278 $ 526,447 Intersegment revenues — 61,026 — 61,026 Operating income 116,191 43,398 (2,971 ) 156,618 Segment assets at period end (3) (*) 2,319,083 131,883 52,772 2,503,738 * Including unconsolidated investments 25,367 — — 25,367
Reconciliation of Operating Profit (Loss) from Segments to Consolidated [Table Text Block]	Three Months Ended September 30, Nine Months Ended September 30, 2018 2017 2018 2017 Revenue: Total segment revenue $ 166,480 $ 157,185 $ 528,802 $ 526,447 Intersegment revenue 9,236 28,248 45,516 61,026 Elimination of intersegment revenue (9,236 ) (28,248 ) (45,516 ) (61,026 ) Total consolidated revenue $ 166,480 $ 157,185 $ 528,802 $ 526,447 Operating income: Operating income $ 25,902 $ 43,970 $ 117,128 $ 156,618 Interest income 214 255 516 861 Interest expense, net (18,700 ) (11,692 ) (48,890 ) (41,155 ) Derivatives and foreign currency transaction gains (losses) (383 ) (1,001 ) (2,511 ) 2,040 Income attributable to sale of tax benefits 4,066 3,506 14,983 14,019 Other non-operating income (expense), net 309 (1,592 ) 7,662 (1,678 ) Total consolidated income before income taxes and equity in income of investees $ 11,408 $ 33,446 $ 88,888 $ 130,705

Note 1 - General and Basis of_3

Note 1 - General and Basis of Presentation (Details Textual)	May 17, 2018USD ($)	Apr. 24, 2018USD ($)MWh	Mar. 22, 2018USD ($)	Sep. 30, 2018USD ($)	Jun. 30, 2018USD ($)	Sep. 30, 2017USD ($)	Sep. 30, 2018USD ($)	Sep. 30, 2017USD ($)	Dec. 31, 2017USD ($)
Insured Event, Gain (Loss)							$ 7,150,000
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax				$ 6,000,000		$ 2,000,000	16,000,000	56,000,000
Interest Expense, Total				18,700,000		11,692,000	48,890,000	41,155,000
Income Tax Expense (Benefit), Total				1,184,000		6,224,000	3,347,000	49,993,000
Accumulated Other Comprehensive Income (Loss), Net of Tax, Total				(1,386,000)			(1,386,000)		$ (4,706,000)
Exploration Abandonment and Impairment Expense				0		$ 0	119,000	$ 0
Accounts Receivable, Net, Current, Total				$ 118,675,000			118,675,000		$ 110,410,000
Provision for Doubtful Accounts							$ 0
Accounts Receivable [Member] | Customer Concentration Risk [Member] | Primary Customers [Member]
Concentration Risk, Percentage							53.00%		57.00%
Sales Revenue, Net [Member] | Customer Concentration Risk [Member] | Sierra Pacific Power Company And Nevada Power Company [Member]
Concentration Risk, Percentage				13.60%		16.30%	15.70%	17.40%
Sales Revenue, Net [Member] | Customer Concentration Risk [Member] | Southern California Public Power Authority [Member]
Concentration Risk, Percentage				13.70%		9.10%	14.90%	8.90%
Sales Revenue, Net [Member] | Customer Concentration Risk [Member] | Kenya Power and Lighting Co LTD [Member]
Concentration Risk, Percentage				18.60%		17.60%	16.70%	15.70%
UNITED STATES
Cash, Cash Equivalents, and Short-term Investments, Total				$ 20,900,000			$ 20,900,000		$ 21,200,000
Foreign Countries [Member]
Cash, Cash Equivalents, and Short-term Investments, Total				76,800,000			76,800,000		32,800,000
Accounts Receivable, Net, Current, Total				92,600,000			92,600,000		$ 78,100,000
Other Comprehensive Income (Loss) [Member]
Accumulated Other Comprehensive Income (Loss), Net of Tax, Total				900,000			900,000
Reclassification out of Accumulated Other Comprehensive Income [Member]
Interest Expense, Total				6,000,000		$ (9,000,000)	22,000,000	$ 21,000,000
Income Tax Expense (Benefit), Total				0		$ (11,000,000)	5,000,000	$ (35,000,000)
Migdal Loan [Member]
Debt Instrument, Face Amount			$ 100,000,000
Debt Instrument, Periodic Payment, Total			4,200,000
Debt Instrument, Periodic Payment Terms, Balloon Payment to be Paid			$ 37,000,000
Debt Instrument, Interest Rate, Stated Percentage			4.80%
Debt Instrument Increase in Stated Interest Rate if Rating is Downgraded to ILA Negative			0.50%
Debt Instrument Increase in Stated Interest Rate Each Additional Downgrade			0.25%
Debt Instrument Decrease in Stated Interest Rate for Each Rating Upgrade			0.25%
Debt to EBITDA Ratio Threshold for Rate Increase			4.5
Debt Instrument Increase in Stated Interest Rate if Debt to EBITDA Ratio Exceeds Threshold			0.50%
Debt to EBITDA Ratio Requirement			6
Stockholders Equity, Debt Covenant, Minimum Threshold			$ 650,000,000
Stockholders Equity to Total Assets, Ratio			25.00%
Stockholders Equity, Debt Covenant, Minimum Threshold to Pay Dividends			$ 800,000,000
Dividends to Net Income, Ratio			50.00%
Migdal Loan [Member] | Maximum [Member]
Debt Instrument, Increase in Stated Interest Rate			1.00%
Migdal Loan [Member] | Minimum [Member]
Debt Instrument, Interest Rate, Stated Percentage			4.80%
U.S. Geothermal [Member]
Payments to Acquire Businesses, Gross		$ 110,000,000
Current Power Generation | MWh		38
Business Combination, Pro Forma Information, Revenue of Acquiree since Acquisition Date, Actual				7,300,000			10,700,000
Business Acquisition, Pro Forma Operating Income (Loss) since Acquisition Date, Actual				1,600,000			(2,600,000)
U.S. Geothermal [Member] | Neal Hot Springs [Member]
Business Combination, Acquisition of Less than 100 Percent, Noncontrolling Interest, Fair Value		$ 34,900,000
Business Combination, Acquisition of Less than 100 Percent, Noncontrolling Interest, Percent		40.00%
U.S. Geothermal [Member] | Neal Hot Springs [Member] | Measurement Input, Expected Term [Member]
Noncontrolling Interest, Measurement Input		20
U.S. Geothermal [Member] | Neal Hot Springs [Member] | Measurement Input, Discount Rate [Member]
Noncontrolling Interest, Measurement Input		0.09
U.S. Geothermal [Member] | Long-term Electricity Power Purchase Agreements [Member]
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life		19 years
U.S. Geothermal [Member] | Ormat Nevada Inc. [Member]
Payments to Acquire Businesses, Gross		$ 106,000,000
U.S. Geothermal [Member] | Ormat Technologies, Inc. [Member]
Payments to Acquire Businesses, Gross		$ 4,000,000
Puna Geothermal Power Plant [Member]
Impairment of Long-Lived Assets Held-for-use					$ 4,900,000
Puna Geothermal Power Plant [Member] | Other Income [Member]
Insured Event, Gain (Loss)					$ 7,200,000
Tungsten Mountain [Member]
Parternship Agreement, Initial Purchase Price	$ 33,400,000
Partnership Agreement, Expected Additional Installments	$ 13,000,000
Partnership Agreement, Percentage of Distributable Cash Flow Generated	97.50%
Partnership Agreement, Percentage of Taxable Income	95.00%
Galena 2 Power Purchase Agreement [Member]
Termination Fees				$ 5,000,000			$ 5,000,000

Note 1 - General and Basis of_4

Note 1 - General and Basis of Presentation - Fair Value of Amounts of Identified Assets and Liabilities Assumed in a Business Combination (Details) - USD ($) $ in Thousands		Sep. 30, 2018	Apr. 24, 2018	Dec. 31, 2017
Goodwill (2)		$ 40,111		$ 21,037
U.S. Geothermal [Member]
Cash and cash equivalents and restricted cash			$ 37,900
Property, plant and equipment and construction-in-process			77,300
Intangible assets (1)	[1]		127,000
Goodwill (2)	[2]		19,300
Total assets acquired			261,500
Other working capital			(8,200)
Deferred tax liability			(4,900)
Long-term term debt			(98,300)
Asset retirement obligation			(9,000)
Noncontrolling interest			(34,900)
Total liabilities assumed			(155,300)
Total assets acquired, and liabilities assumed, net			$ 106,200
[1]	Intangible assets are primarily related to long-term electricity power purchase agreements and depreciated over an average of 19 years.
[2]	Goodwill is primarily related to the expected synergies in operations as a result of the purchase transaction and allocated to the Electricity segment.

Note 1 - General and Basis of_5

Note 1 - General and Basis of Presentation - Summary of Unaudited Pro Forma Information Related to a Business Combination (Details) - U.S. Geothermal [Member] - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Revenues	$ 166,480	$ 157,185	$ 540,099	$ 548,007
Operating income	25,902	43,210	115,582	157,609
Electricity Segment [Member]
Revenues	$ 116,891	$ 117,688	$ 382,856	$ 359,108

Note 1 - General and Basis of_6

Note 1 - General and Basis of Presentation - Cash and Restricted Cash and Cash Equivalents (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017	Sep. 30, 2017	Dec. 31, 2016
Cash and cash equivalents	$ 71,965	$ 47,818
Restricted cash and cash equivalents	83,101	48,825
Total Cash and cash equivalents and restricted cash and cash equivalents	$ 155,066	$ 96,643	$ 119,771	$ 264,476

Note 2 - New Accounting Prono_3

Note 2 - New Accounting Pronouncements 1 (Details Textual) - USD ($) $ in Thousands	Jan. 01, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2018
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period				2 years
Deferred Costs, Total			$ 49,834
Accounting Standards Update 2014-09 [Member]
Cumulative Effect on Retained Earnings, Net of Tax, Total	$ 24,000
Accounting Standards Update 2016-16 [Member]
Cumulative Effect on Retained Earnings, Net of Tax, Total		$ 1,800
Deferred Costs, Total		49,800
Deferred Tax Assets, Net, Noncurrent		$ 51,600
Accounting Standards Update 2016-15 [Member] | Reclassifcation of Cash Paid From Investing Activities to Financing Activities [Member]
Prior Period Reclassification Adjustment			$ 8,000
Product Segment [Member]
Revenue, Remaining Performance Obligation, Amount				$ 226,400

Note 2 - New Accounting Prono_4

Note 2 - New Accounting Pronouncements 2 (Details Textual)	Sep. 30, 2018
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2018-10-01
Revenue, Remaining Performance Obligation, Percentage	99.00%

Note 2 - New Accounting Prono_5

Note 2 - New Accounting Pronouncements - Impact of Adoption (Details) - USD ($) $ in Thousands	Jan. 01, 2018	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Investment in an unconsolidated company		$ 67,739		$ 67,739		$ 34,084
Total consolidated revenues		166,480	$ 157,185	528,802	$ 526,447
Equity in earnings (losses) of investees, net		(117)	337	1,481	(1,690)
Income from continuing operations		10,107	27,559	87,022	79,022
Net income attributable to the Company’s stockholders		10,581	23,960	79,746	67,794
Retained earnings as of the end of the period		410,870		410,870		$ 327,255
Calculated under Revenue Guidance in Effect before Topic 606 [Member]
Equity in earnings (losses) of investees, net		(15)		(1,308)
Income from continuing operations		10,209		84,233
Net income attributable to the Company’s stockholders		10,683		76,957
Retained earnings as of the end of the period		410,972		410,972
Electricity [Member]
Revenues		116,891	110,876	371,559	337,548
Product [Member]
Revenues		48,439	44,912	152,026	186,621
Other Revenue [Member]
Revenues		1,150	$ 1,397	5,217	$ 2,278
Accounting Standards Update 2014-09 [Member]
Investment in an unconsolidated company	$ 24,000
Accounting Standards Update 2014-09 [Member] | Difference between Revenue Guidance in Effect before and after Topic 606 [Member]
Equity in earnings (losses) of investees, net		(102)		2,789
Income from continuing operations		(102)		2,789
Net income attributable to the Company’s stockholders		(102)		2,789
Retained earnings as of the end of the period		(102)		(102)
Accounting Standards Update 2014-09 [Member] | Electricity [Member]
Revenues
Electricity Revenues accounted under ASC 840, Leases		111,114		353,859
Accounting Standards Update 2014-09 [Member] | Electricity and Product Revenue [Member]
Revenues		$ 55,366		$ 174,943
Accounting Standards Update 2014-09 [Member] | Product [Member]
Revenues
Accounting Standards Update 2014-09 [Member] | Other Revenue [Member]
Revenues

Note 2 - New Accounting Prono_6

Note 2 - New Accounting Pronouncements - Contract Assets (Liabilities) (Details) - USD ($) $ in Thousands		9 Months Ended
		Sep. 30, 2018	Dec. 31, 2017
Contract assets (*)	[1]	$ 47,811	$ 40,945
Contract liabilities (*)	[1]	(21,760)	(20,241)
Contract assets, net		26,051	$ 20,704
Recognition of contract liabilities as revenue as a result of performance obligations satisfied, liabilities		22,504
Cash received in advance for which revenues have not yet recognized, net expenditures made, liabilities		(29,796)
Reduction of contract assets as a result of rights to consideration becoming unconditional, assets		(87,510)
Contract assets recognized, net of recognized receivables, assets		100,150
Net change in contract assets and contract liabilities, assets		12,640
Net change in contract assets and contract liabilities, liabilities		$ (7,292)
[1]	Contract assets and contract liabilities are presented as "Costs and estimated earnings in excess of billings on uncompleted contracts" and "Billings in excess of costs and estimated earnings on uncompleted contracts", respectively, on the consolidated balance sheet.

Note 3 - Inventories - Inventor

Note 3 - Inventories - Inventories, Current (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Raw materials and purchased parts for assembly	$ 26,604	$ 12,007
Self-manufactured assembly parts and finished products	10,838	7,544
Total	$ 37,442	$ 19,551

Note 4 - Investment in an Unc_3

Note 4 - Investment in an Unconsolidated Company (Details Textual)	Jan. 01, 2018USD ($)	Sep. 30, 2018USD ($)	Sep. 30, 2018USD ($)MWh
Accounting Standards Update 2014-09 [Member]
Cumulative Effect on Retained Earnings, Net of Tax, Total	$ 24,000,000
Sarulla [Member]
Jointly Owned Utility Plant, Proportionate Ownership Share		12.75%	12.75%
Expected Power Generating Capacity | MWh			330
Number of Phases of Construction			3
Power Utilization | MWh			110
Power Plant Usage Agreement Term			30 years
Payments to Acquire Projects		$ 0	$ 3,800,000
Accumulated Cash Contributions to Acquire Projects		62,000,000	$ 62,000,000
Contract Effective Date			April 4, 2013
Sarulla [Member] | Accounting Standards Update 2014-09 [Member]
Equity Method Investments	24,000,000
Cumulative Effect on Retained Earnings, Net of Tax, Total	$ 24,000,000
Sarulla [Member] | Interest Rate Swap [Member]
Accumulated Other Comprehensive Income (Loss), Cumulative Changes in Net Gain (Loss) from Cash Flow Hedges, Effect Net of Tax, Ending Balance		$ 900,000	$ 900,000

Note 4 - Investment in an Unc_4

Note 4 - Investment in an Unconsolidated Company - Unconsolidated Investments Mainly in Power Plants (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Sarulla	$ (8,522)	$ (6,416)
Sarulla [Member]
Sarulla	$ 67,739	$ 34,084

Note 4 - Investment in an Unc_5

Note 4 - Investment in an Unconsolidated Company - Unrealized Gain (Loss) on Derivative Instruments (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Interest Rate Swap [Member] | Sarulla [Member]
Change, net of deferred tax, in unrealized gains (losses) in respect of the Company’s share in derivative instruments of unconsolidated investment	$ 1,012	$ 618	$ 4,175	$ 271

Note 5 - Fair Value of Financ_3

Note 5 - Fair Value of Financial Instruments (Details Textual) - Henry Hub Natural Gas Future ("NG") Contracts [Member] - Put Option [Member] BTU in Millions, $ in Millions	Jan. 12, 2017USD ($)BTU$ / BTU
Derivative, Nonmonetary Notional Amount, Energy Measure | BTU	4.1
Derivative, Price Risk Option Strike Price | $ / BTU	3
Payments for Derivative Instrument, Investing Activities | $	$ 0.7

Note 5 - Fair Value of Financ_4

Note 5 - Fair Value of Financial Instruments - Financial Assets and Liabilities at Fair Value (Details) - USD ($) $ in Thousands		Sep. 30, 2018	Dec. 31, 2017
Reported Value Measurement [Member]
Cash equivalents (including restricted cash accounts)		$ 15,941	$ 18,359
		2,038	1,588
Reported Value Measurement [Member] | Contingent Receivable [Member]
Derivative Asset, Current	[1]	105	108
Reported Value Measurement [Member] | Currency Forward Contracts [Member]
Derivative Asset, Current	[2]	(210)	992
Reported Value Measurement [Member] | Contingent Payable [Member]
Derivative Liability, Current	[1]	(13,798)	(13,904)
Reported Value Measurement [Member] | Warrant [Member]
Derivative Liability, Current	[1]		(3,967)
Estimate of Fair Value Measurement [Member]
Cash equivalents (including restricted cash accounts)		15,941	18,359
		2,038	1,588
Estimate of Fair Value Measurement [Member] | Contingent Receivable [Member]
Derivative Asset, Current	[1]	105	108
Estimate of Fair Value Measurement [Member] | Currency Forward Contracts [Member]
Derivative Asset, Current	[2]	(210)	992
Estimate of Fair Value Measurement [Member] | Contingent Payable [Member]
Derivative Liability, Current	[1]	(13,798)	(13,904)
Estimate of Fair Value Measurement [Member] | Warrant [Member]
Derivative Liability, Current	[1]		(3,967)
Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 1 [Member]
Cash equivalents (including restricted cash accounts)		15,941	18,359
		15,941	18,359
Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 1 [Member] | Contingent Receivable [Member]
Derivative Asset, Current	[1]
Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 1 [Member] | Currency Forward Contracts [Member]
Derivative Asset, Current	[2]
Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 1 [Member] | Contingent Payable [Member]
Derivative Liability, Current	[1]
Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 1 [Member] | Warrant [Member]
Derivative Liability, Current	[1]
Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 2 [Member]
Cash equivalents (including restricted cash accounts)
		(210)	992
Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 2 [Member] | Contingent Receivable [Member]
Derivative Asset, Current	[1]
Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 2 [Member] | Currency Forward Contracts [Member]
Derivative Asset, Current	[2]	(210)	992
Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 2 [Member] | Contingent Payable [Member]
Derivative Liability, Current	[1]
Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 2 [Member] | Warrant [Member]
Derivative Liability, Current	[1]
Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 3 [Member]
Cash equivalents (including restricted cash accounts)
		(13,693)	(17,763)
Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 3 [Member] | Contingent Receivable [Member]
Derivative Asset, Current	[1]	105	108
Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 3 [Member] | Currency Forward Contracts [Member]
Derivative Asset, Current	[2]
Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 3 [Member] | Contingent Payable [Member]
Derivative Liability, Current	[1]	$ (13,798)	(13,904)
Estimate of Fair Value Measurement [Member] | Fair Value, Inputs, Level 3 [Member] | Warrant [Member]
Derivative Liability, Current	[1]		$ (3,967)
[1]	These amounts relate to contingent receivables and payables and warrants relating to acquisition of substantially all of the assets of Viridity Energy, Inc. and to the Guadeloupe power plant purchase transaction, valued primarily based on unobservable inputs and are included within "Prepaid expenses and other", "Accounts payable and accrued expenses" and "Other long-term liabilities" on September 30, 2018 and 2017 in the consolidated balance sheets with the corresponding gain or loss being recognized within Derivatives and foreign currency transaction gains (losses) in the consolidated statement of operations and comprehensive income.
[2]	These amounts relate to currency forward contracts valued primarily based on observable inputs, including forward and spot prices for currencies, net of contracted rates and then multiplied by notional amounts, and are included within "Prepaid expenses and other" and "Accounts payable and accrued expenses", as applicable, on September 30, 2018 and December 31, 2017, in the consolidated balance sheet with the corresponding gain or loss being recognized within "Derivatives and foreign currency transaction gains (losses)" in the consolidated statement of operations and comprehensive income.

Note 5 - Fair Value of Financ_5

Note 5 - Fair Value of Financial Instruments - Amounts of Gain (Loss) Recognized in Condensed Consolidated Statements on Derivative Instruments Not Designated as Hedges (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Amount of gain (loss) recognized	$ (198)	$ (1,027)	$ (1,655)	$ 2,356
Foreign Currency Gain (Loss) [Member] | Put Options on Natural Gas Price [Member]
Amount of gain (loss) recognized		(121)		(362)
Foreign Currency Gain (Loss) [Member] | Contingent Considerations [Member]
Amount of gain (loss) recognized		(19)		(114)
Foreign Currency Gain (Loss) [Member] | Currency Forward Contracts [Member]
Amount of gain (loss) recognized	$ (198)	$ (887)	$ (1,655)	$ 2,832

Note 5 - Fair Value of Financ_6

Note 5 - Fair Value of Financial Instruments - Fair Value of Long-term Debt Approximates Its Carrying Amount, Exceptions (Details) - USD ($) $ in Millions	Sep. 30, 2018	Dec. 31, 2017
Estimate of Fair Value Measurement [Member]
Other long-term debt	$ 5.4	$ 7
Reported Value Measurement [Member]
Other long-term debt	6.4	7.9
Olkaria III OPIC [Member]
Loans	214.2	234.6
Olkaria III OPIC [Member] | Estimate of Fair Value Measurement [Member]
Loans	214.2	234.6
Olkaria III OPIC [Member] | Reported Value Measurement [Member]
Loans	215.1	228.6
Olkaria IV Loan - DEG 2 [Member]
Loans	50.1
Olkaria IV Loan - DEG 2 [Member] | Estimate of Fair Value Measurement [Member]
Loans	50.1	50.7
Olkaria IV Loan - DEG 2 [Member] | Reported Value Measurement [Member]
Loans	50	50
Amatitlan Loan [Member]
Loans	30.8	32.8
Amatitlan Loan [Member] | Estimate of Fair Value Measurement [Member]
Loans	30.8	32.8
Amatitlan Loan [Member] | Reported Value Measurement [Member]
Loans	30.6	33.3
OrCal Geothermal Inc [Member]
Notes	24.7	34.2
OrCal Geothermal Inc [Member] | Estimate of Fair Value Measurement [Member]
Notes	24.7	34.2
OrCal Geothermal Inc [Member] | Reported Value Measurement [Member]
Notes	24	32.1
OFC Two Senior Secured Notes [Member]
Notes	215.9	234.6
OFC Two Senior Secured Notes [Member] | Estimate of Fair Value Measurement [Member]
Notes	215.9	234.6
OFC Two Senior Secured Notes [Member] | Reported Value Measurement [Member]
Notes	221.8	232.5
Don A. Campbell 1 ("DAC1") [Member]
Notes	79	85.5
Don A. Campbell 1 ("DAC1") [Member] | Estimate of Fair Value Measurement [Member]
Notes	79	85.5
Don A. Campbell 1 ("DAC1") [Member] | Reported Value Measurement [Member]
Notes	84.7	88.3
USG Prudential - NV [Member]
Notes	29.4
USG Prudential - NV [Member] | Estimate of Fair Value Measurement [Member]
Notes	29.4
USG Prudential - NV [Member] | Reported Value Measurement [Member]
Notes	28.2
USG Prudential - ID [Member]
Notes	18.7
USG Prudential - ID [Member] | Estimate of Fair Value Measurement [Member]
Notes	18.7
USG Prudential - ID [Member] | Reported Value Measurement [Member]
Notes	18.9
USG DOE [Member]
Notes	47.2
USG DOE [Member] | Estimate of Fair Value Measurement [Member]
Notes	47.2
USG DOE [Member] | Reported Value Measurement [Member]
Notes	51.4
Senior Unsecured Bonds [Member]
Senior secured debt	195.7	200.3
Senior Unsecured Bonds [Member] | Estimate of Fair Value Measurement [Member]
Senior secured debt	195.7	200.3
Senior Unsecured Bonds [Member] | Reported Value Measurement [Member]
Senior secured debt	204.3	204.3
Senior Unsecured Loan [Member]
Senior secured debt	99.7
Senior Unsecured Loan [Member] | Estimate of Fair Value Measurement [Member]
Senior secured debt	99.7
Senior Unsecured Loan [Member] | Reported Value Measurement [Member]
Senior secured debt	$ 100

Note 5 - Fair Value of Financ_7

Note 5 - Fair Value of Financial Instruments - Fair Value of Financial Instruments (Details) - USD ($) $ in Millions	Sep. 30, 2018	Dec. 31, 2017
Revolving lines of credit	$ 209.5	$ 51.5
Deposits	14.2	15.6
Fair Value, Inputs, Level 1 [Member]
Revolving lines of credit
Deposits	14.2	15.6
Fair Value, Inputs, Level 2 [Member]
Revolving lines of credit	209.5	51.5
Deposits
Fair Value, Inputs, Level 3 [Member]
Revolving lines of credit
Deposits
Olkaria III OPIC [Member]
Loans	214.2	234.6
Olkaria III OPIC [Member] | Fair Value, Inputs, Level 1 [Member]
Loans
Olkaria III OPIC [Member] | Fair Value, Inputs, Level 2 [Member]
Loans
Olkaria III OPIC [Member] | Fair Value, Inputs, Level 3 [Member]
Loans	214.2	234.6
Olkaria IV Loan - DEG 2 [Member]
Loans	50.1
Olkaria IV Loan - DEG 2 [Member] | Fair Value, Inputs, Level 1 [Member]
Loans
Olkaria IV Loan - DEG 2 [Member] | Fair Value, Inputs, Level 2 [Member]
Loans
Olkaria IV Loan - DEG 2 [Member] | Fair Value, Inputs, Level 3 [Member]
Loans	50.1	50.7
Amatitlan Loan [Member]
Loans	30.8	32.8
Amatitlan Loan [Member] | Fair Value, Inputs, Level 1 [Member]
Loans
Amatitlan Loan [Member] | Fair Value, Inputs, Level 2 [Member]
Loans	30.8	32.8
Amatitlan Loan [Member] | Fair Value, Inputs, Level 3 [Member]
Loans
OrCal Geothermal Inc [Member]
Notes	24.7	34.2
OrCal Geothermal Inc [Member] | Fair Value, Inputs, Level 1 [Member]
Notes
OrCal Geothermal Inc [Member] | Fair Value, Inputs, Level 2 [Member]
Notes
OrCal Geothermal Inc [Member] | Fair Value, Inputs, Level 3 [Member]
Notes	24.7	34.2
OFC Senior Secured Notes [Member]
Notes
OFC Senior Secured Notes [Member] | Fair Value, Inputs, Level 1 [Member]
Notes
OFC Senior Secured Notes [Member] | Fair Value, Inputs, Level 2 [Member]
Notes
OFC Senior Secured Notes [Member] | Fair Value, Inputs, Level 3 [Member]
Notes
OFC Two Senior Secured Notes [Member]
Notes	215.9	234.6
OFC Two Senior Secured Notes [Member] | Fair Value, Inputs, Level 1 [Member]
Notes
OFC Two Senior Secured Notes [Member] | Fair Value, Inputs, Level 2 [Member]
Notes
OFC Two Senior Secured Notes [Member] | Fair Value, Inputs, Level 3 [Member]
Notes	215.9	234.6
Don A. Campbell 1 ("DAC1") [Member]
Notes	79	85.5
Don A. Campbell 1 ("DAC1") [Member] | Fair Value, Inputs, Level 1 [Member]
Notes
Don A. Campbell 1 ("DAC1") [Member] | Fair Value, Inputs, Level 2 [Member]
Notes
Don A. Campbell 1 ("DAC1") [Member] | Fair Value, Inputs, Level 3 [Member]
Notes	79	85.5
USG Prudential - NV [Member]
Notes	29.4
USG Prudential - NV [Member] | Fair Value, Inputs, Level 1 [Member]
Notes
USG Prudential - NV [Member] | Fair Value, Inputs, Level 2 [Member]
Notes
USG Prudential - NV [Member] | Fair Value, Inputs, Level 3 [Member]
Notes	29.4
USG Prudential - ID [Member]
Notes	18.7
USG Prudential - ID [Member] | Fair Value, Inputs, Level 1 [Member]
Notes
USG Prudential - ID [Member] | Fair Value, Inputs, Level 2 [Member]
Notes
USG Prudential - ID [Member] | Fair Value, Inputs, Level 3 [Member]
Notes	18.7
Senior Unsecured Bonds [Member]
Senior secured debt	195.7	200.3
Senior Unsecured Bonds [Member] | Fair Value, Inputs, Level 1 [Member]
Senior secured debt
Senior Unsecured Bonds [Member] | Fair Value, Inputs, Level 2 [Member]
Senior secured debt
Senior Unsecured Bonds [Member] | Fair Value, Inputs, Level 3 [Member]
Senior secured debt	195.7	200.3
USG DOE [Member]
Notes	47.2
USG DOE [Member] | Fair Value, Inputs, Level 1 [Member]
Notes
USG DOE [Member] | Fair Value, Inputs, Level 2 [Member]
Notes
USG DOE [Member] | Fair Value, Inputs, Level 3 [Member]
Notes	47.2
Other Long-term Debt [Member]
Senior secured debt		7
Other long-term debt	5.4
Other Long-term Debt [Member] | Fair Value, Inputs, Level 1 [Member]
Senior secured debt
Other long-term debt
Other Long-term Debt [Member] | Fair Value, Inputs, Level 2 [Member]
Senior secured debt
Other long-term debt
Other Long-term Debt [Member] | Fair Value, Inputs, Level 3 [Member]
Senior secured debt		$ 7
Other long-term debt	5.4
Senior Unsecured Loan [Member]
Senior secured debt	99.7
Senior Unsecured Loan [Member] | Fair Value, Inputs, Level 1 [Member]
Senior secured debt
Senior Unsecured Loan [Member] | Fair Value, Inputs, Level 2 [Member]
Senior secured debt
Senior Unsecured Loan [Member] | Fair Value, Inputs, Level 3 [Member]
Senior secured debt	$ 99.7

Note 6 - Stock-based Compensa_3

Note 6 - Stock-based Compensation (Details Textual) - $ / shares	Jun. 25, 2018	May 08, 2018	May 07, 2018	May 31, 2012
2012 Stock Incentive Plan [Member] | Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Expiration Period				6 years
2012 Stock Incentive Plan [Member] | Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Expiration Period				10 years
2012 Stock Incentive Plan [Member] | Stock Options And Stock Appreciation Rights [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized				4,000,000
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period				1 year
2012 Stock Incentive Plan [Member] | Stock Options And Stock Appreciation Rights [Member] | Share-based Compensation Award, Tranche One [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage				25.00%
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period				2 years
2012 Stock Incentive Plan [Member] | Stock Options And Stock Appreciation Rights [Member] | Share-based Compensation Award, Tranche One [Member] | Director [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage				100.00%
2012 Stock Incentive Plan [Member] | Stock Options And Stock Appreciation Rights [Member] | Share-based Compensation Award, Tranche Two [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage				25.00%
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period				3 years
2012 Stock Incentive Plan [Member] | Stock Options And Stock Appreciation Rights [Member] | Share-based Compensation Award, Tranche Three [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage				50.00%
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period				4 years
2012 Stock Incentive Plan [Member] | Stock Options And Stock Appreciation Rights [Member] | Share-based Compensation Award, Tranche Four [Member] | Senior Management [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage				25.00%
2012 Stock Incentive Plan [Member] | Employee Stock Option [Member] | Non Employee Director [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period				1 year
The 2018 Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized			5,000,000
The 2018 Incentive Plan [Member] | Stock Appreciation Rights and Restricted Stock Units [Member] | Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Expiration Period			6 years
The 2018 Incentive Plan [Member] | Stock Appreciation Rights and Restricted Stock Units [Member] | Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Expiration Period			10 years
The 2018 Incentive Plan [Member] | Stock Appreciation Rights and Restricted Stock Units [Member] | Share-based Compensation Award, Tranche One [Member] | Director [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage		100.00%	100.00%
The 2018 Incentive Plan [Member] | Stock Appreciation Rights and Restricted Stock Units [Member] | Share-based Compensation Award, Tranche One [Member] | Employees [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage			50.00%
The 2018 Incentive Plan [Member] | Stock Appreciation Rights and Restricted Stock Units [Member] | Share-based Compensation Award, Tranche One [Member] | Employees and Senior Management [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage	50.00%
The 2018 Incentive Plan [Member] | Stock Appreciation Rights and Restricted Stock Units [Member] | Share-based Compensation Award, Tranche One [Member] | Chief Executive Officer [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage		22.00%
The 2018 Incentive Plan [Member] | Stock Appreciation Rights and Restricted Stock Units [Member] | Share-based Compensation Award, Tranche Two [Member] | Employees [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage			25.00%
The 2018 Incentive Plan [Member] | Stock Appreciation Rights and Restricted Stock Units [Member] | Share-based Compensation Award, Tranche Two [Member] | Employees and Senior Management [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage	25.00%
The 2018 Incentive Plan [Member] | Stock Appreciation Rights and Restricted Stock Units [Member] | Share-based Compensation Award, Tranche Two [Member] | Chief Executive Officer [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage		22.00%
The 2018 Incentive Plan [Member] | Stock Appreciation Rights and Restricted Stock Units [Member] | Share-based Compensation Award, Tranche Three [Member] | Employees [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage			25.00%
The 2018 Incentive Plan [Member] | Stock Appreciation Rights and Restricted Stock Units [Member] | Share-based Compensation Award, Tranche Three [Member] | Employees and Senior Management [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage	25.00%
The 2018 Incentive Plan [Member] | Stock Appreciation Rights and Restricted Stock Units [Member] | Share-based Compensation Award, Tranche Three [Member] | Chief Executive Officer [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage		28.00%
The 2018 Incentive Plan [Member] | Stock Appreciation Rights and Restricted Stock Units [Member] | Share-based Compensation Award, Tranche Four [Member] | Chief Executive Officer [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Rights, Percentage		28.00%
The 2018 Incentive Plan [Member] | Stock Appreciation Rights (SARs) [Member] | Director [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period		295,671
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value		$ 14.56
The 2018 Incentive Plan [Member] | Stock Appreciation Rights (SARs) [Member] | Senior Management [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value	$ 14.64
The 2018 Incentive Plan [Member] | Stock Appreciation Rights (SARs) [Member] | Employees [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period	838,117
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value	$ 13.82
The 2018 Incentive Plan [Member] | Stock Appreciation Rights (SARs) [Member] | Employees and Senior Management [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Expiration Period	6 years
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value	$ 53.44
The 2018 Incentive Plan [Member] | Stock Appreciation Rights (SARs) [Member] | Chief Executive Officer [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period		295,671
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value		$ 14.57
The 2018 Incentive Plan [Member] | Stock Appreciation Rights (SARs) [Member] | Director and Chief Executive Officer [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Expiration Period		5 years 182 days
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Exercise Price		$ 55.16
The 2018 Incentive Plan [Member] | Restricted Stock Units (RSUs) [Member] | Director [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period		40,489
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value		$ 54.92
The 2018 Incentive Plan [Member] | Restricted Stock Units (RSUs) [Member] | Senior Management [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value	$ 52.09
The 2018 Incentive Plan [Member] | Restricted Stock Units (RSUs) [Member] | Employees [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period	19,848
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value	$ 52.03
The 2018 Incentive Plan [Member] | Restricted Stock Units (RSUs) [Member] | Employees and Senior Management [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Expiration Period	6 years
The 2018 Incentive Plan [Member] | Restricted Stock Units (RSUs) [Member] | Chief Executive Officer [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period		40,489
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value		$ 54.23
The 2018 Incentive Plan [Member] | Restricted Stock Units (RSUs) [Member] | Director and Chief Executive Officer [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Expiration Period		5 years 182 days

Note 6 - Stock-based Compensa_4

Note 6 - Stock-based Compensation - Fair Value of Stock-based Award Using Exercise Multiple-based Lattice SAR and RSU Pricing Model Assumptions (Details) - Stock Appreciation Rights and Restricted Stock Units [Member] - The 2018 Incentive Plan [Member]	Jun. 25, 2018	May 08, 2018
Director and Chief Executive Officer [Member]
Risk-free interest rate		2.84%
Expected life (in years) (Year)		5 years 182 days
Dividend yield		0.79%
Expected volatility		25.24%
Forfeiture rate		0.00%
Sub-Optimal Exercise Factor		2.5
Employees and Senior Management [Member]
Risk-free interest rate	2.79%
Expected life (in years) (Year)	6 years
Dividend yield	0.92%
Expected volatility	25.64%
Employees [Member]
Forfeiture rate	2.78%
Sub-Optimal Exercise Factor	2
Senior Management [Member]
Forfeiture rate	0.00%
Sub-Optimal Exercise Factor	2.8

Note 7 - Interest Expense, Ne_2

Note 7 - Interest Expense, Net - Components of Interest Expense (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Interest related to sale of tax benefits	$ 2,916	$ 1,607	$ 6,086	$ 5,468
Interest expense	16,571	13,299	45,298	41,620
Less — amount capitalized	(787)	(3,214)	(2,494)	(5,933)
Interest Expense, Total	$ 18,700	$ 11,692	$ 48,890	$ 41,155

Note 8 - Earnings Per Share (De

Note 8 - Earnings Per Share (Details Textual) - shares	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	388,193	8,851	205,990	6,494

Note 8 - Earnings Per Share - S

Note 8 - Earnings Per Share - Shares Used to Calculate Earnings Per Share (Details) - shares shares in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Weighted average number of shares used in computation of basic earnings per share (in shares)	50,645	50,367	50,627	49,942
Additional shares from the assumed exercise of employee stock options (in shares)	318	500	358	727
Weighted average number of shares used in computation of diluted earnings per share (in shares)	50,963	50,867	50,985	50,669

Note 9 - Business Segments (Det

Note 9 - Business Segments (Details Textual) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2018USD ($)	Sep. 30, 2018USD ($)	Dec. 31, 2017USD ($)	Sep. 30, 2017USD ($)
Number of Reportable Segments		3
Goodwill, Ending Balance	$ 40,111	$ 40,111	$ 21,037
Electricity Segment [Member]
Goodwill, Ending Balance	26,700	26,700		$ 6,800
Other Segments [Member]
Goodwill, Ending Balance	13,500	13,500		$ 13,500
Accounting Standards Update 2014-09 [Member] | Electricity Revenues [Member]
Revenue from Contract with Customer, Including Assessed Tax	$ 5,800	$ 17,700

Note 9 - Business Segments - Su

Note 9 - Business Segments - Summarized Financial Information Concerning Reportable Segments (Details) - USD ($) $ in Thousands		3 Months Ended				9 Months Ended
		Sep. 30, 2018		Sep. 30, 2017		Sep. 30, 2018		Sep. 30, 2017		Dec. 31, 2017
Total consolidated revenues		$ 166,480		$ 157,185		$ 528,802		$ 526,447
Segment assets at period end		3,059,583	[1]	2,503,738	[1]	3,059,583	[1]	2,503,738	[1]	$ 2,623,864
Including unconsolidated investments		67,739		25,367		67,739		25,367
Operating income		25,902		43,970		117,128		156,618
Intersegment Eliminations [Member]
Total consolidated revenues		9,236		28,248		45,516		61,026
Electricity Segment [Member]
Total consolidated revenues		116,891		110,876		371,559		337,548
Segment assets at period end	[1]	2,859,354		2,319,083		2,859,354		2,319,083
Including unconsolidated investments		67,739		25,367		67,739		25,367
Operating income				37,279		94,024		116,191
Electricity Segment [Member] | Intersegment Eliminations [Member]
Total consolidated revenues
Product Segment [Member]
Total consolidated revenues		48,439		44,912		152,026		186,621
Segment assets at period end	[1]	125,881		131,883		125,881		131,883
Including unconsolidated investments
Operating income				7,765		27,614		43,398
Product Segment [Member] | Intersegment Eliminations [Member]
Total consolidated revenues		9,236		28,248		45,516		61,026
Other Segments [Member]
Total consolidated revenues		1,150		1,397		5,217		2,278
Segment assets at period end	[1]	74,348		52,772		74,348		52,772
Including unconsolidated investments
Operating income				(1,074)		(4,510)		(2,971)
Other Segments [Member] | Intersegment Eliminations [Member]
Total consolidated revenues
UNITED STATES
Total consolidated revenues	[2]	66,336				227,446
UNITED STATES | Electricity Segment [Member]
Total consolidated revenues	[2]	64,905				221,727
UNITED STATES | Product Segment [Member]
Total consolidated revenues	[2]	281				502
UNITED STATES | Other Segments [Member]
Total consolidated revenues	[2]	1,150				5,217
Foreign Countries [Member]
Total consolidated revenues	[3]	100,144				301,356
Foreign Countries [Member] | Electricity Segment [Member]
Total consolidated revenues	[3]	51,986				149,832
Foreign Countries [Member] | Product Segment [Member]
Total consolidated revenues	[3]	48,158				151,524
Foreign Countries [Member] | Other Segments [Member]
Total consolidated revenues	[3]
[1]	Electricity segment assets include goodwill in the amount of $26.7 million and $6.8 million as of September 30, 2018 and 2017, respectively. Other segment assets include goodwill in the amount of $13.5 million as of September 30, 2018 and 2017.
[2]	Electricity segment revenues in the United States are all accounted under ASC 840, Leases, except for $5.8 million and $17.7 million in the three and nine months ended September 30, 2018 that are accounted under ASC 606 starting in 2018. Product and Other segment revenues in the United States are accounted under ASC 606, as further described under Note 2 to the consolidated financial statements.
[3]	Electricity segment revenues in foreign countries are all accounted under ASC 840, Leases, and Product revenues in foreign countries are accounted under ASC 606 as further described under Note 2 to the consolidated financial statements.

Note 9 - Business Segments - Re

Note 9 - Business Segments - Reconciling Information Between Reportable Segments and Consolidated Totals (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Total consolidated revenues	$ 166,480	$ 157,185	$ 528,802	$ 526,447
Operating income	25,902	43,970	117,128	156,618
Interest income	214	255	516	861
Interest expense, net	(18,700)	(11,692)	(48,890)	(41,155)
Derivatives and foreign currency transaction gains (losses)	(383)	(1,001)	(2,511)	2,040
Income attributable to sale of tax benefits	4,066	3,506	14,983	14,019
Other non-operating income (expense), net	309	(1,592)	7,662	(1,678)
Total consolidated income before income taxes and equity in income of investees	11,408	33,446	88,888	130,705
Intersegment Eliminations [Member]
Total consolidated revenues	9,236	28,248	45,516	61,026
Consolidation, Eliminations [Member]
Total consolidated revenues	$ (9,236)	$ (28,248)	$ (45,516)	$ (61,026)

Note 10 - Commitments and Con_2

Note 10 - Commitments and Contingencies (Details Textual) $ in Millions	Mar. 29, 2016USD ($)	Sep. 30, 2018
Loss Contingency, New Claims Filed, Number		4
Former Local Sales Representative vs. Ormat [Member] | Pending Litigation [Member]
Loss Contingency, Damages Sought, Value	$ 4.6
Loss Contingency, Additional Damages Sought for Ormat Geothermal Products Sales in Chile, Percent	3.75%
Loss Contingency, Damages Sought, Ormat Geothermal Products Sales in Chile, Period	10 years

Note 11 - Income Taxes (Details

Note 11 - Income Taxes (Details Textual) - USD ($) $ in Millions	3 Months Ended			9 Months Ended		12 Months Ended
	Sep. 30, 2018	Mar. 31, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2018	Dec. 31, 2017
Effective Income Tax Rate Reconciliation, Percent, Total	10.40%		18.60%	3.80%	38.20%
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent				21.00%			35.00%
Income Tax Expense (Benefit), Continuing Operations, Adjustment of Deferred Tax (Asset) Liability		$ (44.4)		$ (27.5)
Reduction of DTA Related to Foreign Tax Credits [Member]
Income Tax Expense (Benefit), Continuing Operations, Adjustment of Deferred Tax (Asset) Liability				$ 29.8
Scenario, Forecast [Member]
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent						21.00%
Foreign Tax Authority [Member] | Kenya Revenue Authority [Member]
National Corporate Tax Rate				37.50%
Foreign Tax Authority [Member] | Israel Tax Authority [Member]
National Corporate Tax Rate				16.00%

Note 12 - Subsequent Events (De

Note 12 - Subsequent Events (Details Textual) - USD ($)	Nov. 06, 2018	Oct. 31, 2018	May 08, 2018	Jun. 30, 2019	Sep. 30, 2018	Sep. 30, 2017
Dividends, Common Stock, Total					$ 21,766,000	$ 16,612,000
Platanares Finance Agreement [Member] | OPIC [Member] | Scenario, Forecast [Member] | Maximum [Member]
Proceeds from Issuance of Debt				$ 10,000,000
Director [Member] | Stock Appreciation Rights (SARs) [Member] | The 2018 Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period			295,671
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value			$ 14.56
Director [Member] | Restricted Stock Units (RSUs) [Member] | The 2018 Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period			40,489
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value			$ 54.92
Subsequent Event [Member]
Dividends, Common Stock, Total	$ 5,100,000
Common Stock, Dividends, Per Share, Declared	$ 0.10
Dividends Payable, Date Declared	Nov. 6, 2018
Dividends Payable, Date of Record	Nov. 20, 2018
Dividends Payable, Date to be Paid	Dec. 4, 2018
Subsequent Event [Member] | Platanares Finance Agreement [Member] | OPIC [Member]
Debt Agreement, Maximum Borrowing Capacity		$ 124,700,000
Proceeds from Issuance of Debt		$ 114,700,000
Debt Instrument, Interest Rate, Stated Percentage		7.02%
Debt Instrument, Term		14 years
Subsequent Event [Member] | Stock Appreciation Rights (SARs) [Member] | The 2018 Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Expiration Period	6 years
Subsequent Event [Member] | Restricted Stock Units (RSUs) [Member] | The 2018 Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Expiration Period	6 years
Subsequent Event [Member] | Director [Member] | The 2018 Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Grant Value for Each Individual	$ 120,000
Subsequent Event [Member] | Director [Member] | Stock Appreciation Rights (SARs) [Member] | The 2018 Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period	15,395
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value	$ 14.80
Subsequent Event [Member] | Director [Member] | Restricted Stock Units (RSUs) [Member] | The 2018 Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period	17,338
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value	$ 52.60
Subsequent Event [Member] | Board of Directors Chairman [Member] | The 2018 Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Grant Value for Each Individual	$ 180,000