FAIR VALUE OF FINANCIAL INSTRUMENTS - Financial Assets and Liabilities at Fair Value (Details) - USD ($) $ in Millions	Jun. 30, 2024	Dec. 31, 2023
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Finance liability - Dixie Valley	$ 224.8	$ 207.2
Deposits	19.9	20.9
Fair Value, Inputs, Level 1
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Finance liability - Dixie Valley	0.0	0.0
Deposits	19.9	20.9
Fair Value, Inputs, Level 2
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Finance liability - Dixie Valley	0.0	0.0
Deposits	0.0	0.0
Fair Value, Inputs, Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Finance liability - Dixie Valley	224.8	207.2
Deposits	0.0	0.0
Hapoalim 2024 Loan Agreement
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans payable, fair value disclosure	73.2
Hapoalim 2024 Loan Agreement | Fair Value, Inputs, Level 1
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans payable, fair value disclosure	0.0
Hapoalim 2024 Loan Agreement | Fair Value, Inputs, Level 2
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans payable, fair value disclosure	0.0
Hapoalim 2024 Loan Agreement | Fair Value, Inputs, Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans payable, fair value disclosure	73.2
HSBC 2024 Loan Agreement
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans payable, fair value disclosure	127.5
HSBC 2024 Loan Agreement | Fair Value, Inputs, Level 1
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans payable, fair value disclosure	0.0
HSBC 2024 Loan Agreement | Fair Value, Inputs, Level 2
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans payable, fair value disclosure	0.0
HSBC 2024 Loan Agreement | Fair Value, Inputs, Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans payable, fair value disclosure	127.5
Mammoth Senior Secured Notes
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Notes payable, fair value disclosure	150.7
Mammoth Senior Secured Notes | Fair Value, Inputs, Level 1
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Notes payable, fair value disclosure	0.0
Mammoth Senior Secured Notes | Fair Value, Inputs, Level 2
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Notes payable, fair value disclosure	0.0
Mammoth Senior Secured Notes | Fair Value, Inputs, Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Notes payable, fair value disclosure	150.7
Discount 2024 Loan
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans payable, fair value disclosure	32.5
Discount 2024 Loan | Fair Value, Inputs, Level 1
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans payable, fair value disclosure	0.0
Discount 2024 Loan | Fair Value, Inputs, Level 2
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans payable, fair value disclosure	0.0
Discount 2024 Loan | Fair Value, Inputs, Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans payable, fair value disclosure	32.5
Mizrahi Loan Agreement
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans payable, fair value disclosure	56.2	61.4
Mizrahi Loan Agreement | Fair Value, Inputs, Level 1
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans payable, fair value disclosure	0.0	0.0
Mizrahi Loan Agreement | Fair Value, Inputs, Level 2
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans payable, fair value disclosure	0.0	0.0
Mizrahi Loan Agreement | Fair Value, Inputs, Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans payable, fair value disclosure	56.2	61.4
Mizrahi 2023 Loan Agreement
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans payable, fair value disclosure	48.4	52.0
Mizrahi 2023 Loan Agreement | Fair Value, Inputs, Level 1
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans payable, fair value disclosure	0.0	0.0
Mizrahi 2023 Loan Agreement | Fair Value, Inputs, Level 2
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans payable, fair value disclosure	0.0	0.0
Mizrahi 2023 Loan Agreement | Fair Value, Inputs, Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans payable, fair value disclosure	48.4	52.0
Convertible Senior Notes
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Notes payable, fair value disclosure	428.2	444.6
Convertible Senior Notes | Fair Value, Inputs, Level 1
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Notes payable, fair value disclosure	0.0	0.0
Convertible Senior Notes | Fair Value, Inputs, Level 2
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Notes payable, fair value disclosure	428.2	444.6
Convertible Senior Notes | Fair Value, Inputs, Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Notes payable, fair value disclosure	0.0	0.0
HSBC Loan Agreement
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans payable, fair value disclosure	30.5	33.8
HSBC Loan Agreement | Fair Value, Inputs, Level 1
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans payable, fair value disclosure	0.0	0.0
HSBC Loan Agreement | Fair Value, Inputs, Level 2
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans payable, fair value disclosure	0.0	0.0
HSBC Loan Agreement | Fair Value, Inputs, Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans payable, fair value disclosure	30.5	33.8
Hapoalim Loan Agreement
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans payable, fair value disclosure	66.7	75.0
Hapoalim Loan Agreement | Fair Value, Inputs, Level 1
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans payable, fair value disclosure	0.0	0.0
Hapoalim Loan Agreement | Fair Value, Inputs, Level 2
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans payable, fair value disclosure	0.0	0.0
Hapoalim Loan Agreement | Fair Value, Inputs, Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans payable, fair value disclosure	66.7	75.0
Hapoalim Loan Agreement 2023
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans payable, fair value disclosure	93.0	99.7
Hapoalim Loan Agreement 2023 | Fair Value, Inputs, Level 1
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans payable, fair value disclosure	0.0	0.0
Hapoalim Loan Agreement 2023 | Fair Value, Inputs, Level 2
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans payable, fair value disclosure	0.0	0.0
Hapoalim Loan Agreement 2023 | Fair Value, Inputs, Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans payable, fair value disclosure	93.0	99.7
Discount Loan Agreement
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans payable, fair value disclosure	63.9	69.9
Discount Loan Agreement | Fair Value, Inputs, Level 1
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans payable, fair value disclosure	0.0	0.0
Discount Loan Agreement | Fair Value, Inputs, Level 2
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans payable, fair value disclosure	0.0	0.0
Discount Loan Agreement | Fair Value, Inputs, Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans payable, fair value disclosure	63.9	69.9
Olkaria III Loan DFC
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans payable, fair value disclosure	107.1	116.4
Olkaria III Loan DFC | Fair Value, Inputs, Level 1
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans payable, fair value disclosure	0.0	0.0
Olkaria III Loan DFC | Fair Value, Inputs, Level 2
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans payable, fair value disclosure	0.0	0.0
Olkaria III Loan DFC | Fair Value, Inputs, Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans payable, fair value disclosure	107.1	116.4
Olkaria III Plant 4 Loan - DEG 2
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans payable, fair value disclosure	19.2	21.6
Olkaria III Plant 4 Loan - DEG 2 | Fair Value, Inputs, Level 1
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans payable, fair value disclosure	0.0	0.0
Olkaria III Plant 4 Loan - DEG 2 | Fair Value, Inputs, Level 2
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans payable, fair value disclosure	0.0	0.0
Olkaria III Plant 4 Loan - DEG 2 | Fair Value, Inputs, Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans payable, fair value disclosure	19.2	21.6
Olkaria III plant 1 Loan - DEG 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans payable, fair value disclosure	16.9	19.0
Olkaria III plant 1 Loan - DEG 3 | Fair Value, Inputs, Level 1
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans payable, fair value disclosure	0.0	0.0
Olkaria III plant 1 Loan - DEG 3 | Fair Value, Inputs, Level 2
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans payable, fair value disclosure	0.0	0.0
Olkaria III plant 1 Loan - DEG 3 | Fair Value, Inputs, Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans payable, fair value disclosure	16.9	19.0
DEG 4 Loan
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans payable, fair value disclosure	30.7
DEG 4 Loan | Fair Value, Inputs, Level 1
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans payable, fair value disclosure	0.0
DEG 4 Loan | Fair Value, Inputs, Level 2
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans payable, fair value disclosure	0.0
DEG 4 Loan | Fair Value, Inputs, Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans payable, fair value disclosure	30.7
Platanares Loan - OPIC
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans payable, fair value disclosure	66.5	71.3
Platanares Loan - OPIC | Fair Value, Inputs, Level 1
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans payable, fair value disclosure	0.0	0.0
Platanares Loan - OPIC | Fair Value, Inputs, Level 2
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans payable, fair value disclosure	0.0	0.0
Platanares Loan - OPIC | Fair Value, Inputs, Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans payable, fair value disclosure	66.5	71.3
OFC Two Senior Secured Notes
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans payable, fair value disclosure		134.2
Notes payable, fair value disclosure	124.8
OFC Two Senior Secured Notes | Fair Value, Inputs, Level 1
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Notes payable, fair value disclosure	0.0
OFC Two Senior Secured Notes | Fair Value, Inputs, Level 2
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Notes payable, fair value disclosure	0.0
OFC Two Senior Secured Notes | Fair Value, Inputs, Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans payable, fair value disclosure		134.2
Notes payable, fair value disclosure	124.8
Don A. Campbell 1 ("DAC1")
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans payable, fair value disclosure		52.3
Notes payable, fair value disclosure	49.1
Don A. Campbell 1 ("DAC1") | Fair Value, Inputs, Level 1
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Notes payable, fair value disclosure	0.0
Don A. Campbell 1 ("DAC1") | Fair Value, Inputs, Level 2
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Notes payable, fair value disclosure	0.0
Don A. Campbell 1 ("DAC1") | Fair Value, Inputs, Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans payable, fair value disclosure		52.3
Notes payable, fair value disclosure	49.1
USG Prudential - NV
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Notes payable, fair value disclosure	21.7	22.3
USG Prudential - NV | Fair Value, Inputs, Level 1
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Notes payable, fair value disclosure	0.0	0.0
USG Prudential - NV | Fair Value, Inputs, Level 2
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Notes payable, fair value disclosure	0.0	0.0
USG Prudential - NV | Fair Value, Inputs, Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Notes payable, fair value disclosure	21.7	22.3
USG Prudential - ID
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Notes payable, fair value disclosure	52.0	54.1
USG Prudential - ID | Fair Value, Inputs, Level 1
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Notes payable, fair value disclosure	0.0	0.0
USG Prudential - ID | Fair Value, Inputs, Level 2
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Notes payable, fair value disclosure	0.0	0.0
USG Prudential - ID | Fair Value, Inputs, Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Notes payable, fair value disclosure	52.0	54.1
USG DOE
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Notes payable, fair value disclosure	28.4	30.0
USG DOE | Fair Value, Inputs, Level 1
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Notes payable, fair value disclosure	0.0	0.0
USG DOE | Fair Value, Inputs, Level 2
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Notes payable, fair value disclosure	0.0	0.0
USG DOE | Fair Value, Inputs, Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Notes payable, fair value disclosure	28.4	30.0
Senior Unsecured Bonds
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Long-term debt, fair value	169.2	202.8
Senior Unsecured Bonds | Fair Value, Inputs, Level 1
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Long-term debt, fair value	0.0	0.0
Senior Unsecured Bonds | Fair Value, Inputs, Level 2
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Long-term debt, fair value	0.0	0.0
Senior Unsecured Bonds | Fair Value, Inputs, Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Long-term debt, fair value	169.2	202.8
Senior Unsecured Loan
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Long-term debt, fair value	141.5	150.4
Senior Unsecured Loan | Fair Value, Inputs, Level 1
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Long-term debt, fair value	0.0	0.0
Senior Unsecured Loan | Fair Value, Inputs, Level 2
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Long-term debt, fair value	0.0	0.0
Senior Unsecured Loan | Fair Value, Inputs, Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Long-term debt, fair value	141.5	150.4
Other Long-term Debt
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Other long-term debt	5.6	6.8
Other Long-term Debt | Fair Value, Inputs, Level 1
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Other long-term debt	0.0	0.0
Other Long-term Debt | Fair Value, Inputs, Level 2
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Other long-term debt	0.0	0.0
Other Long-term Debt | Fair Value, Inputs, Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Other long-term debt	$ 5.6	$ 6.8