Summary of Significant Accounting Policies - Real Estate Loans Receivable (Details)	Dec. 31, 2018 mezzanine_loan
Mezzanine Loan Receivable
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans	10
Term Loan Receivable
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans	1

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.

No definition available.

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Balance Type:	na
Period Type:	duration