Note 12 - Long-term Debt, Credit Agreements and Finance Liability (Details Textual) $ in Thousands, ₪ in Billions																1 Months Ended		12 Months Ended
		Nov. 28, 2022 USD ($)	Jun. 27, 2022 USD ($)	Apr. 12, 2022 USD ($)	Sep. 02, 2021 USD ($)	Jul. 15, 2021 USD ($)	Jul. 12, 2021 USD ($)	Jul. 20, 2020 USD ($)	May 30, 2019	Apr. 09, 2019 USD ($)	Mar. 25, 2019 USD ($)	Mar. 22, 2018 USD ($)	Dec. 21, 2016 USD ($)	Jul. 31, 2015 USD ($) MWh	Feb. 29, 2012	Oct. 31, 2018 MWh	May 31, 2013	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)	Jan. 28, 2022	Jul. 13, 2021 USD ($)	Jul. 01, 2020 USD ($)	Jul. 01, 2020 ILS (₪)	Apr. 30, 2020 USD ($)	Dec. 31, 2019 USD ($)	May 04, 2019 USD ($)	Apr. 29, 2019	Apr. 04, 2019 USD ($)	Jan. 04, 2019 USD ($)	Apr. 30, 2018 USD ($)	May 31, 2017 USD ($)	Nov. 29, 2016 USD ($)	Oct. 20, 2016 USD ($)	May 31, 2016 USD ($)	Aug. 29, 2014 USD ($)	Aug. 23, 2012 USD ($)	Oct. 31, 2011 USD ($)	Sep. 30, 2011 USD ($)	Aug. 31, 2011 USD ($)
Long-Term Debt, Total																		$ 2,052,601
Letters of Credit Outstanding, Amount																		$ 197,400
Debt To Earnings Before Interest Tax Depreciation And Amortization Ratio																		4.13
Stockholders' Equity Attributable to Parent, Ending Balance																		$ 1,867,571	$ 1,854,999
Percentage Of Company Assets																		43.80%
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest, Ending Balance																		$ 2,020,975	1,998,461	$ 1,941,437						$ 1,515,410
Payments of Dividends, Total																		27,100	$ 27,000	$ 22,500
Covenant Requirement Minimum [Member]
Stockholders' Equity Attributable to Parent, Ending Balance																		$ 750,000
Percentage Of Company Assets																		25.00%
Maximum [Member] | Covenant Requirement Minimum [Member]
Debt To Earnings Before Interest Tax Depreciation And Amortization Ratio																		6
Pomona Energy Storage [Member]
Business Combination, Consideration Transferred, Total								$ 43,400
Two Contracted Geothermal Assets in Nevada [Member]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finance Lease Liability	[1]																					$ 258,400
Mizrahi Loan Agreement [Member]
Debt Instrument, Face Amount				$ 75,000														$ 75,000
Debt Instrument, Number of Semi-annual Payments				16
Debt Instrument, Periodic Payment, Total				$ 4,700
Debt Instrument, Term (Year)				8 years
Debt Instrument, Covenant, Maximum Debt to EBITDA Ratio				6.0
Debt Instrument, Covenant, Minimum Equity Capital, Amount				$ 750,000
Debt Instrument, Covenant, Equity Capital to Total Assets, Percent				25.00%
Debt Instrument, Interest Rate, Stated Percentage	[2]																	4.10%
Long-Term Debt, Gross																		$ 70,300
Hapoalim Loan Agreement [Member] | Bank Hapoalim B.M. [Member]
Debt Instrument, Face Amount							$ 125,000
Debt Instrument, Number of Semi-annual Payments							14
Debt Instrument, Periodic Payment, Total							$ 8,900
Debt Instrument, Term (Year)							7 years
Debt Instrument, Covenant, Maximum Debt to EBITDA Ratio							6
Debt Instrument, Covenant, Minimum Equity Capital, Amount							$ 750,000
Debt Instrument, Covenant, Equity Capital to Total Assets, Percent							25.00%
HSBC Loan Agreement [Member] | HSBC Bank PLC [Member]
Debt Instrument, Face Amount						$ 50,000
Debt Instrument, Number of Semi-annual Payments						14
Debt Instrument, Periodic Payment, Total						$ 3,600
Debt Instrument, Term (Year)						7 years
Debt Instrument, Covenant, Maximum Debt to EBITDA Ratio						6
Debt Instrument, Covenant, Minimum Equity Capital, Amount						$ 750,000
Debt Instrument, Covenant, Equity Capital to Total Assets, Percent						25.00%
Discount Loan Agreement [Member]
Debt Instrument, Face Amount																		$ 100,000
Debt Instrument, Interest Rate, Stated Percentage	[2]																	2.90%
Long-Term Debt, Gross																		$ 87,500
Discount Loan Agreement [Member] | Israel Discount Bank Ltd. [Member]
Debt Instrument, Face Amount					$ 100,000
Debt Instrument, Number of Semi-annual Payments					16
Debt Instrument, Periodic Payment, Total					$ 6,250
Debt Instrument, Term (Year)					8 years
Debt Instrument, Covenant, Maximum Debt to EBITDA Ratio					6
Debt Instrument, Covenant, Minimum Equity Capital, Amount					$ 750,000
Debt Instrument, Covenant, Equity Capital to Total Assets, Percent					25.00%
Senior Unsecured Bonds, Series 4 [Member]
Debt Instrument, Face Amount																		$ 289,800					$ 289,800	₪ 1
Debt Instrument, Number of Annual Payments																							10	10
Debt Instrument, Interest Rate, Stated Percentage	[2]																	3.35%
Long-Term Debt, Gross																		$ 255,800
Senior Unsecured Bonds, Series 4 [Member] | Cross Currency Interest Rate Contract [Member]
Derivative, Fixed Interest Rate																							4.34%	4.34%
Senior Unsecured Bonds, Series 3 [Member]
Repayments of Long-Term Debt, Total			$ 221,900
Extinguishment of Debt, Amount			218,000
Interest Paid, Including Capitalized Interest, Operating and Investing Activities, Total			2,800
Debt Instrument, Unamortized Premium, Total			$ 1,100
Senior Unsecured Loan (Migdal) [Member]
Debt Instrument, Face Amount												$ 100,000						$ 100,000
Debt Instrument, Periodic Payment, Total												4,200
Debt Instrument, Periodic Payment Terms, Balloon Payment to be Paid												$ 37,000
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 Instrument, Interest Rate, Stated Percentage	[3]																	4.80%
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												$ 750,000
Stockholders Equity to Total Assets, Ratio												25.00%
Long-Term Debt, Gross																		$ 87,400
Senior Unsecured Loan (Migdal) [Member] | Maximum [Member]
Debt Instrument, Increase in Stated Interest Rate												1.00%
Senior Unsecured Loan (Migdal) [Member] | Minimum [Member]
Debt Instrument, Interest Rate, Stated Percentage												4.80%
Additional Migdal Loan [Member]
Debt Instrument, Face Amount											$ 50,000							$ 50,000
Debt Instrument, Number of Semi-annual Payments											15
Debt Instrument, Periodic Payment, Total											$ 2,100
Debt Instrument, Periodic Payment Terms, Balloon Payment to be Paid											$ 18,500
Debt Instrument, Interest Rate, Stated Percentage	[3]																	4.60%
Long-Term Debt, Gross																		$ 43,700
Second Addendum Migdal Loan [Member]
Debt Instrument, Face Amount																		$ 50,000							$ 50,000
Debt Instrument, Number of Semi-annual Payments																									15
Debt Instrument, Periodic Payment Terms, Balloon Payment to be Paid																									$ 18,500
Debt Instrument, Interest Rate, Stated Percentage	[3]																	5.44%
Debt Instrument, Principal to Be Repaid in Installments																									$ 31,500
Long-Term Debt, Gross																		$ 43,700
DEG 2 Facility Agreement [Member]
Debt Instrument, Interest Rate, Stated Percentage													6.28%
Line of Credit Facility, Maximum Borrowing Capacity																																		$ 50,000
Proceeds from Lines of Credit, Total													$ 50,000
DEG 3 Loan Agreement [Member]
Debt Instrument, Number of Semi-annual Payments																														19
Debt Instrument, Interest Rate, Stated Percentage																														6.04%
DEG 3 Loan Agreement [Member] | OrPower 4, Inc [Member]
Debt Instrument, Face Amount																														$ 41,500
Loan Agreement With OPIC the Olkaria III Power Plant [Member]
Debt Instrument, Face Amount																		310,000																			$ 310,000
Long-Term Debt, Gross																		138,700
Platanares Finance Agreement [Member]
Debt Instrument, Face Amount																		$ 114,700
Debt Instrument, Interest Rate, Stated Percentage	[4]																	7.02%
Long-Term Debt, Gross																		$ 79,900
Platanares Finance Agreement [Member] | OPIC [Member]
Debt Instrument, Face Amount																															$ 114,700
Current Power Generation (Megawatt-Hour) | MWh																35
Loan Agreement with Banco Industrial S.A. and Westrust Bank (International) Limited1 [Member]
Debt Instrument, Face Amount														$ 42,000				42,000
Debt Instrument, Term (Year)														12 years
Power Utilization (Megawatt-Hour) | MWh														20
Debt Instrument Number of Quarterly Payments														48
Long-Term Debt, Gross																		$ 15,800
Loan Agreement with Banco Industrial S.A. and Westrust Bank (International) Limited1 [Member] | London Interbank Offered Rate (LIBOR) [Member]
Debt Instrument, Basis Spread on Variable Rate	[4]																	4.35%
Loan Agreement with Banco Industrial S.A. and Westrust Bank (International) Limited1 [Member] | London Interbank Offered Rate (LIBOR) [Member] | Guaranteed [Member]
Debt Instrument, Basis Spread on Variable Rate														4.35%
Loan Agreement with Banco Industrial S.A. and Westrust Bank (International) Limited1 [Member] | London Interbank Offered Rate (LIBOR) [Member] | Not Guaranteed [Member]
Debt Instrument, Basis Spread on Variable Rate														4.75%
Loan Agreement with Banco Industrial S.A. and Westrust Bank (International) Limited1 [Member] | Minimum [Member] | London Interbank Offered Rate (LIBOR) [Member]
Debt Instrument, Basis Spread on Variable Rate														1.25%
Plumstriker Loan Agreement [Member]
Debt Instrument, Face Amount																		$ 23,500
Long-Term Debt, Gross																		$ 11,400
Plumstriker Loan Agreement [Member] | London Interbank Offered Rate (LIBOR) [Member]
Debt Instrument, Basis Spread on Variable Rate	[4]																	3.50%
Plumstriker Loan Agreement [Member] | Plumstriker and its Two Subsidiaries [Member]
Debt Instrument, Face Amount																											$ 23,500
Debt Instrument, Equal Quarterly Principal Installments, Percentage of Loan									1.25%
Plumstriker Loan Agreement [Member] | Plumstriker and its Two Subsidiaries [Member] | London Interbank Offered Rate (LIBOR) [Member]
Debt Instrument, Basis Spread on Variable Rate									3.50%
Don A. Cambell Senior Secured Notes [Member]
Debt Instrument, Face Amount																																	$ 92,500
OFC Two Senior Secured Notes [Member]
Debt Instrument, Face Amount																																						$ 151,700	$ 350,000
Government Guarantee Percent																																							80.00%
OFC Two Senior Secured Notes [Member] | Wholly Owned Subsidiaries With Project Debt [Member]
Debt Instrument, Face Amount																																				$ 140,000
Prudential Capital Group Agreement [Member]
Debt Instrument, Face Amount																																			$ 20,000
Idaho Refinancing Note [Member]
Debt Instrument, Face Amount		$ 61,600
Debt Instrument, Number of Semi-annual Payments																					31
Debt Instrument, Interest Rate, Stated Percentage		6.26%
Idaho Refinancing Note [Member] | Raft River Energy I LLC [Member]
Debt Instrument, Secured, Percentage of Ownership Interests		100.00%
Idaho Refinancing Note [Member] | Oregon USG Holdings, LLC [Member]
Debt Instrument, Secured, Percentage of Ownership Interests		60.00%
Idaho Refinancing Note [Member] | Revolving Note Tranche [Member]
Line of Credit Facility, Maximum Borrowing Capacity		$ 4,300
Line of Credit Facility, Unused Capacity, Commitment Fee Percentage		0.50%
Idaho Refinancing Note [Member] | Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member] | Revolving Note Tranche [Member]
Debt Instrument, Basis Spread on Variable Rate		1.40%
USG Prudential - ID [Member]
Long-Term Debt, Total		$ 16,000
DOE Loan Guarantee [Member]
Line of Credit Facility, Maximum Borrowing Capacity																																								$ 96,800
Loan Agreement with Bpifrance [Member] | Guadeloupe 1 [Member]
Debt Instrument, Face Amount																													$ 8,900
Debt Instrument, Interest Rate, Stated Percentage																												1.93%
Long-Term Debt, Gross																		$ 5,800
Loan Agreement with Société Général [Member] | Guadeloupe 1 [Member]
Debt Instrument, Face Amount										$ 8,900
Debt Instrument, Interest Rate, Stated Percentage										1.52%
Debt Instrument Number of Quarterly Payments										28
Long-Term Debt, Gross																		4,600
Credit Agreements With Eight Commercial Banks [Member]
Line of Credit Facility, Maximum Borrowing Capacity																		623,000
Long-term Line of Credit, Total																		0
Letters of Credit Outstanding, Amount																		90,700
Credit Agreements With Eight Commercial Banks [Member] | Extensions of Credit in The Form of Loans and/or Letters of Credit [Member]
Line of Credit Facility, Maximum Borrowing Capacity																		408,000
Credit Agreements With Eight Commercial Banks [Member] | Letter of Credit [Member]
Line of Credit Facility, Maximum Borrowing Capacity																		120,000
Credit Agreements With Eight Commercial Banks [Member] | Union Bank, N.A. [Member]
Line of Credit Facility, Maximum Borrowing Capacity																		60,000
Credit Agreements With Eight Commercial Banks [Member] | HSBC Bank USA, N.A. [Member]
Line of Credit Facility, Maximum Borrowing Capacity																		35,000
Long-Term Debt, Gross																		528,000
Union Bank, N.A. [Member]
Line of Credit Facility, Maximum Borrowing Capacity																		60,000
Long-term Line of Credit, Total																		$ 57,600
Debt To Earnings Before Interest Tax Depreciation And Amortization Ratio																		2.04
Debt Services, Coverage Ratio																		3.91
Amount Available For Dividend Distribution Percent Of Cumulative Net Income															2.0			0.63
Union Bank, N.A. [Member] | Maximum [Member]
Debt To Earnings Before Interest Tax Depreciation And Amortization Ratio															4.5
Union Bank, N.A. [Member] | Minimum [Member]
Debt Services, Coverage Ratio															1.35
HSBC Bank USA, N.A. [Member]
Line of Credit Facility, Maximum Borrowing Capacity																		$ 35,000
Long-term Line of Credit, Total																		$ 34,200
Debt To Earnings Before Interest Tax Depreciation And Amortization Ratio																		2.04
Debt Services, Coverage Ratio																		3.91
Amount Available For Dividend Distribution Percent Of Cumulative Net Income																		0.63
Uncommitted Line of Credit Facility, Maximum Borrowing Capacity																		$ 20,000
Uncommitted Long-term Line of Credit																		4,800
HSBC Bank USA, N.A. [Member] | Maximum [Member]
Debt To Earnings Before Interest Tax Depreciation And Amortization Ratio																	4.5
Amount Available For Dividend Distribution Percent Of Cumulative Net Income																	2.0
HSBC Bank USA, N.A. [Member] | Minimum [Member]
Debt To Earnings Before Interest Tax Depreciation And Amortization Ratio																	1.35
Surety Agreement [Member] | Chubb [Member]
Surety Bonds Available																																$ 200,000
Surety Bonds Outstanding																		$ 192,400

[1] Financing liability is related to a sale and leaseback transaction entered into by the Seller in September 2015 under which it sold and leased back the undivided interests in the Dixie Valley power plant asset through June 2038. The lease transaction was accounted for by the Seller as a finance lease due to the Seller's continued involvement and management of the power plant and the existence of an early buy-out option in September 2024, which continues to be applicable to the Company. As per the accounting guidance, the Company retained the Seller's accounting of a "failed" sale and leaseback transaction and accordingly accounted for the liability as a financing liability. This financing liability, as well as the related power plant asset, were measured at their acquisition-date fair value.

[2] payable semi-annually

[3] payable semi-annually in arrears.

[4] payable quarterly