Mortgages Payable (Details)	Dec. 31, 2018 USD ($) property	Dec. 31, 2017 USD ($)
Debt Instrument [Line Items]
Accumulated amortization	$ 14,118,000	$ 12,667,000
Debt costs, net of accumulated amortization	(4,081,000)	(5,380,000)
Long-term Debt, Fiscal Year Maturity [Abstract]
Mortgages payable, including unamortized premium and net of unamortized debt costs	12,694,000	13,300,000
Mortgages
Debt Instrument [Line Items]
Debt costs	(147,000)	(147,000)
Accumulated amortization	73,000	55,000
Debt costs, net of accumulated amortization	(74,000)	(92,000)
Mortgages payable, including unamortized premium and net of unamortized debt costs	12,694,000	13,300,000
Long-term Debt, Fiscal Year Maturity [Abstract]
2019	652,000
2020	682,000
2021	716,000
2022	750,000
2023	9,968,000
Mortgages payable, including unamortized premium and net of unamortized debt costs	12,768,000
Mortgages | November 2014
Debt Instrument [Line Items]
Initial Balance	$ 15,151,000
Interest Rate	5.23%
Carrying Value of Encumbered Asset(s)	$ 20,430,000
Outstanding Principal Balance	$ 12,768,000	$ 13,392,000
Number of encumbered assets | property	5