Real Estate Fund Investments - Schedule of Financial Information of Unconsolidated Real Estate Funds (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Equity Method Investments And Joint Ventures [Abstract]
Real estate investments	$ 405,931	$ 639,609
Cash and cash equivalents	5,076	7,608
Other assets	74	152
Total assets	411,081	647,369
Other liabilities	1,308	1,931
Total liabilities	1,308	1,931
Equity	409,773	645,438
Total liabilities and equity	$ 411,081	$ 647,369