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Related Party Transactions and Investments in Non-Consolidated Entities - Management fees and interest income from loans (Details) - USD ($) | 9 Months Ended
--- | ---
Sep. 30, 2020 | Sep. 30, 2019
Related Party Transactions and Investments in Non-Consolidated Entities |  |
Asset management fees, low end of range (as a percent) | 1.00% |
Asset management fees, high end of range (as a percent) | 5.00% |
Notice period for cancellation of applicable contracts | 30 days |
Revenue | $ 59,000 | $ 152,000
Revenue, Product and Service [Extensible List] | us-gaap:AssetManagement1Member | us-gaap:AssetManagement1Member

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