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Related Party Transactions and Investments in Non-Consolidated Entities - Management fees and interest income from loans (Details) - USD ($) | 12 Months Ended
--- | ---
Dec. 31, 2018 | Dec. 31, 2017 | Dec. 31, 2016
Schedule of Equity Method Investments [Line Items] |  |  |
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 |  |
Impairment of Sponsored REIT | $ 0 |  |
Asset Management Fees |  |  | $ 631,000
Asset Management |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |
Asset Management Fees | $ 450,000 | $ 598,000 |

X
- Definition High end of the range of the asset management fee as a percentage of collected rents. + References No definition available. + Details
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- Definition Low end of the range of the asset management fee as a percentage of collected rents. + References No definition available. + Details
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- Definition Amount of fixed fee revenue for the management of an investment fund portfolio. Excludes investment advisory, distribution and servicing, and performance fees. + References No definition available. + Details
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- Definition Amount of investment of impaired financing receivables with related allowance for credit losses and without a related allowance for credit losses. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 14A -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=84173941&loc=SL6953550-111524 + Details
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