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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

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- Definition

High end of the range of the asset management fee as a percentage of collected rents.

+ References

No definition available.

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- Definition

Low end of the range of the asset management fee as a percentage of collected rents.

+ References

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+ Details

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- Definition

Represents the notice period for cancellation of applicable contracts.

+ References

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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.

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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

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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