Variable Interest Entities ("VIEs") - Summary of Investments in Unconsolidated Real Estate Funds (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Variable Interest Entity [Line Items]
Investments in unconsolidated real estate funds	$ 8,146	$ 28,173
Investment [Member]
Variable Interest Entity [Line Items]
Investments in unconsolidated real estate funds	8,146
Asset Management Fees and Other Receivables [Member]
Variable Interest Entity [Line Items]
Investments in unconsolidated real estate funds	617
Maximum Risk of Loss [Member]
Variable Interest Entity [Line Items]
Investments in unconsolidated real estate funds	$ 8,763