FAIR VALUE OF FINANCIAL INSTRUMENTS - Fair Value of Long-term Debt Approximates Its Carrying Amount, Exceptions (Details) - USD ($) $ in Millions	Sep. 30, 2024	Dec. 31, 2023
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Finance liability - Dixie Valley	$ 220.7	$ 207.2
Estimate of Fair Value Measurement
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Finance liability - Dixie Valley	220.7	207.2
Other long-term debt	4.8	6.8
Reported Value Measurement
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Finance liability - Dixie Valley	220.6	225.8
Other long-term debt	5.0	7.7
Hapoalim 2024 Loan Agreement
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans payable, fair value disclosure	72.1
Hapoalim 2024 Loan Agreement | Estimate of Fair Value Measurement
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans payable, fair value disclosure	72.1	0.0
Hapoalim 2024 Loan Agreement | Reported Value Measurement
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans payable, fair value disclosure	70.3	0.0
HSBC 2024 Loan Agreement
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans payable, fair value disclosure	118.5
HSBC 2024 Loan Agreement | Estimate of Fair Value Measurement
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans payable, fair value disclosure	118.5	0.0
HSBC 2024 Loan Agreement | Reported Value Measurement
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans payable, fair value disclosure	112.5	0.0
Mammoth Senior Secured Notes
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Notes payable, fair value disclosure	158.2
Mammoth Senior Secured Notes | Estimate of Fair Value Measurement
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Notes payable, fair value disclosure	158.2	0.0
Mammoth Senior Secured Notes | Reported Value Measurement
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Notes payable, fair value disclosure	135.1	0.0
Discount 2024 Loan
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans payable, fair value disclosure	31.5
Discount 2024 Loan | Estimate of Fair Value Measurement
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans payable, fair value disclosure	31.5	0.0
Discount 2024 Loan | Reported Value Measurement
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans payable, fair value disclosure	30.8	0.0
Discount 2024 II Loan
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans payable, fair value disclosure	50.0
Discount 2024 II Loan | Estimate of Fair Value Measurement
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans payable, fair value disclosure	50.0	0.0
Discount 2024 II Loan | Reported Value Measurement
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans payable, fair value disclosure	50.0	0.0
Mizrahi Loan Agreement
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans payable, fair value disclosure	58.1	61.4
Mizrahi Loan Agreement | Estimate of Fair Value Measurement
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans payable, fair value disclosure	58.1	61.4
Mizrahi Loan Agreement | Reported Value Measurement
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans payable, fair value disclosure	56.3	60.9
Mizrahi 2023 Loan Agreement
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans payable, fair value disclosure	49.5	52.0
Mizrahi 2023 Loan Agreement | Estimate of Fair Value Measurement
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans payable, fair value disclosure	49.5	52.0
Mizrahi 2023 Loan Agreement | Reported Value Measurement
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans payable, fair value disclosure	46.9	50.0
Convertible Senior Notes
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Notes payable, fair value disclosure	497.8	444.6
Convertible Senior Notes | Estimate of Fair Value Measurement
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Notes payable, fair value disclosure	497.8	444.6
Convertible Senior Notes | Reported Value Measurement
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Notes payable, fair value disclosure	476.4	431.3
HSBC Loan Agreement
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans payable, fair value disclosure	27.3	33.8
HSBC Loan Agreement | Estimate of Fair Value Measurement
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans payable, fair value disclosure	27.3	33.8
HSBC Loan Agreement | Reported Value Measurement
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans payable, fair value disclosure	28.6	35.7
Hapoalim Loan Agreement
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans payable, fair value disclosure	69.1	75.0
Hapoalim Loan Agreement | Estimate of Fair Value Measurement
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans payable, fair value disclosure	69.1	75.0
Hapoalim Loan Agreement | Reported Value Measurement
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans payable, fair value disclosure	71.4	80.4
Hapoalim Loan Agreement 2023
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans payable, fair value disclosure	88.1	99.7
Hapoalim Loan Agreement 2023 | Estimate of Fair Value Measurement
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans payable, fair value disclosure	88.1	99.7
Hapoalim Loan Agreement 2023 | Reported Value Measurement
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans payable, fair value disclosure	85.0	95.0
Discount Loan Agreement
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans payable, fair value disclosure	59.0	69.9
Discount Loan Agreement | Estimate of Fair Value Measurement
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans payable, fair value disclosure	59.0	69.9
Discount Loan Agreement | Reported Value Measurement
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans payable, fair value disclosure	62.5	75.0
Olkaria III Loan DFC
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans payable, fair value disclosure	105.0	116.4
Olkaria III Loan DFC | Estimate of Fair Value Measurement
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans payable, fair value disclosure	105.0	116.4
Olkaria III Loan DFC | Reported Value Measurement
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans payable, fair value disclosure	107.2	120.7
Olkaria III Plant 4 Loan - DEG 2
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans payable, fair value disclosure	19.9	21.6
Olkaria III Plant 4 Loan - DEG 2 | Estimate of Fair Value Measurement
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans payable, fair value disclosure	19.9	21.6
Olkaria III Plant 4 Loan - DEG 2 | Reported Value Measurement
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans payable, fair value disclosure	20.0	22.5
Olkaria III plant 1 Loan - DEG 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans payable, fair value disclosure	17.5	19.0
Olkaria III plant 1 Loan - DEG 3 | Estimate of Fair Value Measurement
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans payable, fair value disclosure	17.5	19.0
Olkaria III plant 1 Loan - DEG 3 | Reported Value Measurement
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans payable, fair value disclosure	17.5	19.7
DEG 4 Loan
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans payable, fair value disclosure	31.9
DEG 4 Loan | Estimate of Fair Value Measurement
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans payable, fair value disclosure	31.9	0.0
DEG 4 Loan | Reported Value Measurement
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans payable, fair value disclosure	30.0	0.0
Platanares Loan - OPIC
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans payable, fair value disclosure	64.7	71.3
Platanares Loan - OPIC | Estimate of Fair Value Measurement
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans payable, fair value disclosure	64.7	71.3
Platanares Loan - OPIC | Reported Value Measurement
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans payable, fair value disclosure	65.5	71.7
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	122.5
OFC Two Senior Secured Notes | Estimate of Fair Value Measurement
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Notes payable, fair value disclosure	122.5	134.2
OFC Two Senior Secured Notes | Reported Value Measurement
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Notes payable, fair value disclosure	131.1	142.5
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	49.5
Don A. Campbell 1 ("DAC1") | Estimate of Fair Value Measurement
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Notes payable, fair value disclosure	49.5	52.3
Don A. Campbell 1 ("DAC1") | Reported Value Measurement
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Notes payable, fair value disclosure	53.6	57.4
USG Prudential - NV
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Notes payable, fair value disclosure	22.1	22.3
USG Prudential - NV | Estimate of Fair Value Measurement
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Notes payable, fair value disclosure	22.1	22.3
USG Prudential - NV | Reported Value Measurement
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Notes payable, fair value disclosure	23.4	23.9
USG Prudential - ID
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Notes payable, fair value disclosure	49.8	54.1
USG Prudential - ID | Estimate of Fair Value Measurement
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Notes payable, fair value disclosure	49.8	54.1
USG Prudential - ID | Reported Value Measurement
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Notes payable, fair value disclosure	55.9	58.9
USG DOE
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Notes payable, fair value disclosure	27.4	30.0
USG DOE | Estimate of Fair Value Measurement
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Notes payable, fair value disclosure	27.4	30.0
USG DOE | Reported Value Measurement
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Notes payable, fair value disclosure	27.4	30.2
Senior Unsecured Bonds
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Long-term debt, fair value	177.2	202.8
Senior Unsecured Bonds | Estimate of Fair Value Measurement
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Long-term debt, fair value	177.2	202.8
Senior Unsecured Bonds | Reported Value Measurement
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Long-term debt, fair value	188.7	220.6
Senior Unsecured Loan
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Long-term debt, fair value	136.0	150.4
Senior Unsecured Loan | Estimate of Fair Value Measurement
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Long-term debt, fair value	136.0	150.4
Senior Unsecured Loan | Reported Value Measurement
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Long-term debt, fair value	$ 141.2	$ 158.0