Variable Interest Entities ("VIEs") - Summary of Investments in Unconsolidated Real Estate Funds and Maximum Risk of Loss from Investments (Details) - Unconsolidated Real Estate Funds [Member] - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Carrying Value of Investments [Member]
Variable Interest Entity [Line Items]
Investments in unconsolidated real estate funds	$ 13,041	$ 10,317
Asset Management Fees and Other Receivables [Member]
Variable Interest Entity [Line Items]
Investments in unconsolidated real estate funds	652	37,563
Maximum Risk of Loss [Member]
Variable Interest Entity [Line Items]
Investments in unconsolidated real estate funds	$ 13,693	$ 47,880