Real Estate Fund Investments - Schedule of Income from Fund Investment (Details) - Unconsolidated Real Estate Funds [Member] - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Property Fund II [Member]
Investment Holdings [Line Items]
Investment expenses	$ 196	$ 687
Net investment (loss) income	(196)	(687)
Net realized losses	(15,201)
Net unrealized (losses) gains	(4,997)	1,425
(Loss) income from real estate fund investments	(20,394)	738
Property Fund III [Member]
Investment Holdings [Line Items]
Investment income	1,140
Investment expenses	10	52
Net investment (loss) income	1,130	(52)
Net realized losses	(5,253)
Net unrealized (losses) gains	(2,989)	625
(Loss) income from real estate fund investments	(7,112)	573
Property Fund VII [Member]
Investment Holdings [Line Items]
Investment income	185
Investment expenses	476	530
Net investment (loss) income	(291)	(530)
Net unrealized (losses) gains	134	1,106
(Loss) income from real estate fund investments	$ (157)	$ 576