Real Estate and Accumulated Depreciation Schedule III (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Real Estate and Accumulated Depreciation
Gross amount carried at close of period		$ 197,428	$ 209,972	$ 265,879	$ 329,643
Accumulated Depreciation		33,678	$ 34,903	$ 29,108	$ 27,569
Real Estate Investments
Real Estate and Accumulated Depreciation
Encumbrances		90,321
Initial cost, Land and Improvements		39,893
Initial cost, Building and Improvements		147,977
Costs capitalized subsequent to acquisition	[1]	9,558
Gross amount carried at close of period		197,428
Accumulated Depreciation		$ 33,678
Gardens Medical Pavilion
Real Estate and Accumulated Depreciation
Depreciable life		25 years
Gardens Medical Pavilion | Real Estate Investments
Real Estate and Accumulated Depreciation
Encumbrances		$ 0
Initial cost, Land and Improvements		5,675
Initial cost, Building and Improvements		13,158
Costs capitalized subsequent to acquisition	[1]	5,254
Gross amount carried at close of period		24,087
Accumulated Depreciation		$ 5,736
River Club and the Townhomes at River Club
Real Estate and Accumulated Depreciation
Depreciable life		25 years
River Club and the Townhomes at River Club | Real Estate Investments
Real Estate and Accumulated Depreciation
Encumbrances		$ 23,511
Initial cost, Land and Improvements		6,639
Initial cost, Building and Improvements		24,789
Costs capitalized subsequent to acquisition	[1]	2,847
Gross amount carried at close of period		34,275
Accumulated Depreciation		$ 9,723
Lakes of Margate
Real Estate and Accumulated Depreciation
Depreciable life		25 years
Lakes of Margate | Real Estate Investments
Real Estate and Accumulated Depreciation
Encumbrances		$ 13,973
Initial cost, Land and Improvements		9,776
Initial cost, Building and Improvements		13,061
Costs capitalized subsequent to acquisition	[1]	4,700
Gross amount carried at close of period		27,537
Accumulated Depreciation		$ 6,025
Arbors Harbor Town
Real Estate and Accumulated Depreciation
Depreciable life		25 years
Arbors Harbor Town | Real Estate Investments
Real Estate and Accumulated Depreciation
Encumbrances		$ 24,153
Initial cost, Land and Improvements		5,413
Initial cost, Building and Improvements		24,713
Costs capitalized subsequent to acquisition	[1]	3,008
Gross amount carried at close of period		33,134
Accumulated Depreciation		$ 7,864
22 Exchange
Real Estate and Accumulated Depreciation
Depreciable life		25 years
22 Exchange | Real Estate Investments
Real Estate and Accumulated Depreciation
Encumbrances		$ 18,963
Initial cost, Land and Improvements		2,380
Initial cost, Building and Improvements		24,786
Costs capitalized subsequent to acquisition	[1]	(8,242)
Gross amount carried at close of period		18,924
Accumulated Depreciation		$ 0
Parkside Apartments
Real Estate and Accumulated Depreciation
Depreciable life		25 years
Parkside Apartments | Real Estate Investments
Real Estate and Accumulated Depreciation
Encumbrances		$ 9,721
Initial cost, Land and Improvements		3,143
Initial cost, Building and Improvements		18,148
Costs capitalized subsequent to acquisition	[1]	1,991
Gross amount carried at close of period		23,282
Accumulated Depreciation		$ 4,210
Addison Landing
Real Estate and Accumulated Depreciation
Depreciable life		25 years
Addison Landing | Real Estate Investments
Real Estate and Accumulated Depreciation
Encumbrances		$ 0
Initial cost, Land and Improvements		6,867
Initial cost, Building and Improvements		29,322
Costs capitalized subsequent to acquisition	[1]	0
Gross amount carried at close of period		36,189
Accumulated Depreciation		$ 120

[1] Includes adjustment to basis, such as impairment losses.