Real Estate Properties - Income Statement Information for Disposal of Property (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Loss from discontinued operations	$ (144)	$ (149)
Discontinued operations
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Rental income	7	28
Real estate taxes	(24)	(23)
Utility expenses	(46)	(50)
Other operating expenses	(53)	(76)
General and administrative	(28)	(28)
Loss from discontinued operations	$ (144)	$ (149)