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Rego Park II Loan Participation - (Narrative) (Details) - Participation Agreement - Rego Park II - USD ($) $ in Thousands |  | 12 Months Ended
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Dec. 31, 2017 | Dec. 31, 2018
Investment In Loan Participation [Line Items] |  |
Interest rate |  | 3.87%
Loan participation balance | $ 198,537 | $ 195,708
LIBOR |  |
Investment In Loan Participation [Line Items] |  |
Basis spread over LIBOR | 1.60% | 1.35%

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