INVESTMENTS IN PARTNERSHIPS (Narrative) (Details) - USD ($) $ in Thousands | Apr. 01, 2021 | Mar. 10, 2021 | Jun. 01, 2018 | May 10, 2021 | Mar. 31, 2021 | Mar. 31, 2020 | Dec. 31, 2021 | Apr. 23, 2021 | Feb. 24, 2021 | Dec. 31, 2020 | Apr. 23, 2020 |
Schedule of Equity Method Investments [Line Items] | | | | | | | | | | | |
Carrying value of equity investments | | | | | $ 355,815 | | | | | $ 376,198 | |
Purchase price paid | | | $ 5,100 | | | | | | | | |
Distributions received from investments in partnerships | | | | | 10,311 | $ 6,564 | | | | | |
Additional advance amount | | | | | 230 | 79,500 | | | | | |
Subsequent Event [Member] | Solar Construction Lending LLC and Solar Development Lending LLC [Member] | | | | | | | | | | | |
Schedule of Equity Method Investments [Line Items] | | | | | | | | | | | |
Capital contribution amount for partnership | | | | $ 44,000 | | | | | | | |
Subsequent Event [Member] | Solar Construction Lending LLC [Member] | | | | | | | | | | | |
Schedule of Equity Method Investments [Line Items] | | | | | | | | | | | |
Committed loan amounts | | | | | | | | $ 105,000 | | | |
Subsequent Event [Member] | Solar Development Lending, LLC [Member] | | | | | | | | | | | |
Schedule of Equity Method Investments [Line Items] | | | | | | | | | | | |
Capital contribution amount for partnership | | | | $ 2,100 | | | | | | | |
U.S. Real Estate Partnerships [Member] | | | | | | | | | | | |
Schedule of Equity Method Investments [Line Items] | | | | | | | | | | | |
Carrying value of equity investments | | | | | 11,401 | | | | | 11,208 | |
U.S. Real Estate Partnerships formed in Q4 2014[Member] | | | | | | | | | | | |
Schedule of Equity Method Investments [Line Items] | | | | | | | | | | | |
Carrying value of equity investments | | | | | $ 11,400 | | | | | | |
Equity method investment, ownership percentage | | | | | 80.00% | | | | | | |
Equity method investment, economic interest percentage | | | | | 78.20% | | | | | | |
Solar Ventures Investment [Member] | | | | | | | | | | | |
Schedule of Equity Method Investments [Line Items] | | | | | | | | | | | |
Carrying value of equity investments | | | | | $ 342,921 | | | | | 363,157 | |
Cumulative basis adjustment | | | $ 4,500 | | 2,000 | | | | | $ 2,200 | |
Amortization expense of basis difference | | | | | $ 200 | $ 200 | | | | | |
Equity method investment, ownership percentage | | | | | 50.00% | | | | | | |
Unfunded loan commitments to borrowers | | | | | $ 82,400 | | | | | | |
Weighted average economic interest percentage on equity method investees | | | | | 37.10% | | | | | | |
Solar Ventures Investment [Member] | Solar Ventures [Member] | | | | | | | | | | | |
Schedule of Equity Method Investments [Line Items] | | | | | | | | | | | |
Unfunded loan commitments to borrowers | | | | | $ 308,100 | | | | | | |
Solar Ventures Investment [Member] | Subsequent Event [Member] | | | | | | | | | | | |
Schedule of Equity Method Investments [Line Items] | | | | | | | | | | | |
Weighted average economic interest percentage on equity method investees | | | | 37.40% | | | | | | | |
Solar Construction Lending LLC [Member] | | | | | | | | | | | |
Schedule of Equity Method Investments [Line Items] | | | | | | | | | | | |
Carrying value of equity investments | | | | | $ 58,200 | | | | | | |
Equity method investment, economic interest percentage | | | | | 34.80% | | | | | 45.20% | |
Solar Construction Lending LLC [Member] | Subsequent Event [Member] | | | | | | | | | | | |
Schedule of Equity Method Investments [Line Items] | | | | | | | | | | | |
Capital contribution amount for partnership | | | | $ 10,000 | | | | | | | |
Equity method investment, economic interest percentage | | | | 32.20% | | | | | | | |
Solar Construction Lending LLC [Member] | Subsequent Event [Member] | Capital Partner | | | | | | | | | | | |
Schedule of Equity Method Investments [Line Items] | | | | | | | | | | | |
Capital contribution amount for partnership | | | | $ 34,000 | | | | | | | |
Solar Permanent Lending LLC [Member] | | | | | | | | | | | |
Schedule of Equity Method Investments [Line Items] | | | | | | | | | | | |
Carrying value of equity investments | | | | | $ 89,400 | | | | | | |
Equity method investment, economic interest percentage | | | | | 45.00% | | | | | 45.00% | |
Solar Permanent Lending LLC [Member] | Subsequent Event [Member] | | | | | | | | | | | |
Schedule of Equity Method Investments [Line Items] | | | | | | | | | | | |
Distributions received from investments in partnerships | | | | 2,100 | | | | | | | |
Solar Permanent Lending LLC [Member] | Subsequent Event [Member] | Capital Partner | | | | | | | | | | | |
Schedule of Equity Method Investments [Line Items] | | | | | | | | | | | |
Distributions received from investments in partnerships | | | | $ 2,600 | | | | | | | |
Solar Development Lending, LLC [Member] | | | | | | | | | | | |
Schedule of Equity Method Investments [Line Items] | | | | | | | | | | | |
Carrying value of equity investments | | | | | $ 195,300 | | | | | | |
Equity method investment, economic interest percentage | | | | | 34.90% | | | | | 42.30% | |
Solar Development Lending, LLC [Member] | Subsequent Event [Member] | | | | | | | | | | | |
Schedule of Equity Method Investments [Line Items] | | | | | | | | | | | |
Equity method investment, economic interest percentage | | | | 36.50% | | | | | | | |
Distributions received from investments in partnerships | | | | $ 10,000 | | | | | | | |
Solar Development Lending, LLC [Member] | Subsequent Event [Member] | Capital Partner | | | | | | | | | | | |
Schedule of Equity Method Investments [Line Items] | | | | | | | | | | | |
Distributions received from investments in partnerships | | | | $ 38,000 | | | | | | | |
SAWHF | | | | | | | | | | | |
Schedule of Equity Method Investments [Line Items] | | | | | | | | | | | |
Carrying value of equity investments | | | | | $ 1,493 | | | | | $ 1,833 | |
Equity method investment, ownership percentage | | | | | 11.85% | | | | | | |
Ercot Projects [Member] | Solar Ventures Investment [Member] | | | | | | | | | | | |
Schedule of Equity Method Investments [Line Items] | | | | | | | | | | | |
Equity method investment, economic interest percentage | | | | | | | | | 45.00% | | |
Fair value loss on debt security | | | | | $ 31,900 | | | | | | |
Loan related interest income losses not recognized | | | | | 16,000 | | | | | | |
ERCOT Project 1 | Solar Permanent Lending LLC [Member] | | | | | | | | | | | |
Schedule of Equity Method Investments [Line Items] | | | | | | | | | | | |
Net settlement cost | | $ 25,500 | | | | | | | | | |
Cash pledged by project | | $ 3,000 | | | | | | | | | |
Fair value loss on debt security | | | | | $ 18,200 | | | | | | |
Increase (decrease) in amended loan amount | $ 7,400 | | | | | | | | | | |
ERCOT Project 1 | Solar Permanent Lending LLC [Member] | Sponsor Equity Loan [Member] | | | | | | | | | | | |
Schedule of Equity Method Investments [Line Items] | | | | | | | | | | | |
Loan | | | | | | | | | | $ 177,500 | |
Percentage of UPB on loan portfolio | | | | | 21.10% | | | | | | |
UPB receivable | | | | | $ 177,500 | | | | | | |
Interest percentage of loan receivable | | | | | 12.00% | | | | | | |
Loans held for investment, fair value | | | | | $ 160,700 | | | | | | |
ERCOT Project 1 | Solar Permanent Lending LLC [Member] | Subsequent Event [Member] | | | | | | | | | | | |
Schedule of Equity Method Investments [Line Items] | | | | | | | | | | | |
Increase (decrease) in amended loan amount | $ 22,500 | | | | | | | | | | |
ERCOT Project 2 | Solar Construction Lending LLC and Solar Development Lending LLC [Member] | | | | | | | | | | | |
Schedule of Equity Method Investments [Line Items] | | | | | | | | | | | |
UPB receivable | | | | | $ 70,300 | | | | | | |
ERCOT Project 2 | Construction Loan [Member[ | Solar Construction Lending LLC [Member] | | | | | | | | | | | |
Schedule of Equity Method Investments [Line Items] | | | | | | | | | | | |
Funded loan amounts | | | | | | | | 37,000 | | | |
ERCOT Project 2 | Sponsor Equity Loan [Member] | Third Party Sponsor Equity [Member] | | | | | | | | | | | |
Schedule of Equity Method Investments [Line Items] | | | | | | | | | | | |
Funded loan amounts | | | | | | | | | | | $ 41,700 |
ERCOT Project 2 | Subsequent Event [Member] | Third Party Sponsor Equity [Member] | | | | | | | | | | | |
Schedule of Equity Method Investments [Line Items] | | | | | | | | | | | |
Committed loan amounts | | | | | | | | $ 84,700 | | | |
ERCOT Project 2 | Solar Ventures Investment [Member] | | | | | | | | | | | |
Schedule of Equity Method Investments [Line Items] | | | | | | | | | | | |
Percentage of UPB on loan portfolio | | | | | 8.40% | | | | | | |
ERCOT Project 2 | Solar Construction Lending LLC [Member] | | | | | | | | | | | |
Schedule of Equity Method Investments [Line Items] | | | | | | | | | | | |
Interest percentage of loan receivable | | | | | | | | 5.00% | | | |
Fair value loss on debt security | | | | | $ 200 | | | | | | |
ERCOT Project 2 | Solar Permanent Lending LLC [Member] | Forecast | | | | | | | | | | | |
Schedule of Equity Method Investments [Line Items] | | | | | | | | | | | |
Loan | | | | | | | $ 32,600 | | | | |
Interest percentage of loan receivable | | | | | | | 5.00% | | | | |
ERCOT Project 2 | Solar Development Lending, LLC [Member] | | | | | | | | | | | |
Schedule of Equity Method Investments [Line Items] | | | | | | | | | | | |
Fair value loss on debt security | | | | | $ 8,300 | | | | | | |
ERCOT Project 3 | Solar Development Lending, LLC [Member] | | | | | | | | | | | |
Schedule of Equity Method Investments [Line Items] | | | | | | | | | | | |
Percentage of UPB on loan portfolio | | | | | 28.60% | | | | | | |
UPB receivable | | | | | $ 240,300 | | | | | | |
Fair value loss on debt security | | | | | 3,700 | | | | | | |
Additional loan advances | | | | | 80,100 | | | | | | |
ERCOT Project 3 | Solar Development Lending, LLC [Member] | | | | | | | | | | | |
Schedule of Equity Method Investments [Line Items] | | | | | | | | | | | |
Loans held for investment, fair value | | | | | $ 245,900 | | | | | | |