Real Estate Properties - Balance Sheet Information for Disposal of Property (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Assets of discontinued operations	$ 12,534	$ 12,541
Liabilities of discontinued operations	81	45
Discontinued Operations, Held-for-sale | Discontinued operations
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Real estate properties, net	12,259	12,260
Other assets	275	281
Assets of discontinued operations	12,534	12,541
Other liabilities	81	45
Liabilities of discontinued operations	$ 81	$ 45