Preferred Equity Investments and Investments in Unconsolidated Real Estate Joint Ventures (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Preferred Equity Investments and Investments in Unconsolidated Real Estate Joint Ventures
Equity Method Investments	$ 108,098	$ 126,444
Alexan CityCentre [Member]
Preferred Equity Investments and Investments in Unconsolidated Real Estate Joint Ventures
Equity Method Investments	14,416	12,788
Alexan Southside Place [Member]
Preferred Equity Investments and Investments in Unconsolidated Real Estate Joint Ventures
Equity Method Investments	25,717	24,866
Helios [Member]
Preferred Equity Investments and Investments in Unconsolidated Real Estate Joint Ventures
Equity Method Investments		23,663
Leigh House [Member]
Preferred Equity Investments and Investments in Unconsolidated Real Estate Joint Ventures
Equity Method Investments		80
Mira Vista [Member]
Preferred Equity Investments and Investments in Unconsolidated Real Estate Joint Ventures
Equity Method Investments	5,250	5,250
Riverside Apartments [Member]
Preferred Equity Investments and Investments in Unconsolidated Real Estate Joint Ventures
Equity Method Investments	13,679	12,342
Strategic Portfolio [Member]
Preferred Equity Investments and Investments in Unconsolidated Real Estate Joint Ventures
Equity Method Investments	22,105	10,183
The Conley, formerly North Creek Apartments
Preferred Equity Investments and Investments in Unconsolidated Real Estate Joint Ventures
Equity Method Investments	15,735	14,964
Thornton Flats [Member]
Preferred Equity Investments and Investments in Unconsolidated Real Estate Joint Ventures
Equity Method Investments	4,600	4,600
Wayford at Concord, formerly Wayforth at Concord
Preferred Equity Investments and Investments in Unconsolidated Real Estate Joint Ventures
Equity Method Investments	6,500	4,683
Whetstone Apartments [Member]
Preferred Equity Investments and Investments in Unconsolidated Real Estate Joint Ventures
Equity Method Investments		12,932
Other Property [Member]
Preferred Equity Investments and Investments in Unconsolidated Real Estate Joint Ventures
Equity Method Investments	$ 96	$ 93