FAIR VALUE OF FINANCIAL INSTRUMENTS - Fair Value of Long-term Debt Approximates Its Carrying Amount, Exceptions (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
Estimate of Fair Value Measurement
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Finance liability - Dixie Valley	224.8	207.2
Other long-term debt	5.6	6.8
Reported Value Measurement
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Finance liability - Dixie Valley	223.3	225.8
Other long-term debt	6.0	7.7
Hapoalim 2024 Loan Agreement
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans payable, fair value disclosure	73.2
Hapoalim 2024 Loan Agreement | Estimate of Fair Value Measurement
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans payable, fair value disclosure	73.2	0.0
Hapoalim 2024 Loan Agreement | Reported Value Measurement
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans payable, fair value disclosure	72.7	0.0
HSBC 2024 Loan Agreement
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans payable, fair value disclosure	127.5
HSBC 2024 Loan Agreement | Estimate of Fair Value Measurement
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans payable, fair value disclosure	127.5	0.0
HSBC 2024 Loan Agreement | Reported Value Measurement
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans payable, fair value disclosure	125.0	0.0
Mammoth Senior Secured Notes
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Notes payable, fair value disclosure	150.7
Mammoth Senior Secured Notes | Estimate of Fair Value Measurement
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Notes payable, fair value disclosure	150.7	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	32.5
Discount 2024 Loan | Estimate of Fair Value Measurement
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans payable, fair value disclosure	32.5	0.0
Discount 2024 Loan | Reported Value Measurement
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans payable, fair value disclosure	31.8	0.0
Mizrahi Loan Agreement
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans payable, fair value disclosure	56.2	61.4
Mizrahi Loan Agreement | Estimate of Fair Value Measurement
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans payable, fair value disclosure	56.2	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	48.4	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	48.4	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	428.2	444.6
Convertible Senior Notes | Estimate of Fair Value Measurement
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Notes payable, fair value disclosure	428.2	444.6
Convertible Senior Notes | Reported Value Measurement
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Notes payable, fair value disclosure	431.3	431.3
HSBC Loan Agreement
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans payable, fair value disclosure	30.5	33.8
HSBC Loan Agreement | Estimate of Fair Value Measurement
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans payable, fair value disclosure	30.5	33.8
HSBC Loan Agreement | Reported Value Measurement
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans payable, fair value disclosure	32.1	35.7
Hapoalim Loan Agreement
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans payable, fair value disclosure	66.7	75.0
Hapoalim Loan Agreement | Estimate of Fair Value Measurement
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans payable, fair value disclosure	66.7	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	93.0	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	93.0	99.7
Hapoalim Loan Agreement 2023 | Reported Value Measurement
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans payable, fair value disclosure	90.0	95.0
Discount Loan Agreement
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans payable, fair value disclosure	63.9	69.9
Discount Loan Agreement | Estimate of Fair Value Measurement
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans payable, fair value disclosure	63.9	69.9
Discount Loan Agreement | Reported Value Measurement
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans payable, fair value disclosure	68.8	75.0
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 | Estimate of Fair Value Measurement
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans payable, fair value disclosure	107.1	116.4
Olkaria III Loan DFC | Reported Value Measurement
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans payable, fair value disclosure	111.7	120.7
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 | Estimate of Fair Value Measurement
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 | 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	16.9	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	16.9	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	30.7
DEG 4 Loan | Estimate of Fair Value Measurement
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans payable, fair value disclosure	30.7	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	66.5	71.3
Platanares Loan - OPIC | Estimate of Fair Value Measurement
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans payable, fair value disclosure	66.5	71.3
Platanares Loan - OPIC | Reported Value Measurement
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans payable, fair value disclosure	67.6	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	124.8
OFC Two Senior Secured Notes | Estimate of Fair Value Measurement
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Notes payable, fair value disclosure	124.8	134.2
OFC Two Senior Secured Notes | Reported Value Measurement
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Notes payable, fair value disclosure	133.7	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	49.1
Don A. Campbell 1 ("DAC1") | Estimate of Fair Value Measurement
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Notes payable, fair value disclosure	49.1	52.3
Don A. Campbell 1 ("DAC1") | Reported Value Measurement
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Notes payable, fair value disclosure	54.3	57.4
USG Prudential - NV
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Notes payable, fair value disclosure	21.7	22.3
USG Prudential - NV | Estimate of Fair Value Measurement
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Notes payable, fair value disclosure	21.7	22.3
USG Prudential - NV | Reported Value Measurement
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Notes payable, fair value disclosure	23.6	23.9
USG Prudential - ID
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Notes payable, fair value disclosure	52.0	54.1
USG Prudential - ID | Estimate of Fair Value Measurement
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Notes payable, fair value disclosure	52.0	54.1
USG Prudential - ID | Reported Value Measurement
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Notes payable, fair value disclosure	57.2	58.9
USG DOE
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Notes payable, fair value disclosure	28.4	30.0
USG DOE | Estimate of Fair Value Measurement
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Notes payable, fair value disclosure	28.4	30.0
USG DOE | Reported Value Measurement
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Notes payable, fair value disclosure	28.8	30.2
Senior Unsecured Bonds
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Long-term debt, fair value	169.2	202.8
Senior Unsecured Bonds | Estimate of Fair Value Measurement
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Long-term debt, fair value	169.2	202.8
Senior Unsecured Bonds | Reported Value Measurement
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Long-term debt, fair value	186.2	220.6
Senior Unsecured Loan
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Long-term debt, fair value	141.5	150.4
Senior Unsecured Loan | Estimate of Fair Value Measurement
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Long-term debt, fair value	141.5	150.4
Senior Unsecured Loan | Reported Value Measurement
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Long-term debt, fair value	$ 149.6	$ 158.0