Real Estate and Real Estate-Related Investments - Consolidated Properties (Details)	12 Months Ended
	Dec. 31, 2017
Gardens Medical Pavilion
Real Estate Properties [Line Items]
Ownership Interest	81.80%
River Club and the Townhomes at River Club
Real Estate Properties [Line Items]
Ownership Interest	85.00%
Lakes of Margate
Real Estate Properties [Line Items]
Ownership Interest	92.50%
Arbors Harbor Town
Real Estate Properties [Line Items]
Ownership Interest	94.00%
22 Exchange
Real Estate Properties [Line Items]
Ownership Interest	90.00%
Parkside Apartments (“Parkside”)
Real Estate Properties [Line Items]
Ownership Interest	90.00%
Flats at Fishers Fishers [Member]
Real Estate Properties [Line Items]
Ownership Interest	100.00%