Held for Sale and Discontinued Operations (Details Textual) $ in Millions	1 Months Ended	3 Months Ended	12 Months Ended
	Oct. 31, 2017 property	Dec. 31, 2017 property Property	Dec. 31, 2017 property	Dec. 31, 2016 USD ($) property	Dec. 31, 2015 USD ($) property
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of properties reclassified to held for sale | Property		8
Number of properties exercising purchase option	7
Number of properties held for sale		8	8	2
Discontinued Operations [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Revenue related to properties sold | $					$ 0.8
Expenses related to sale of real estate | $				$ 0.1	0.1
Impairments related to property held for sale | $				$ 0.1	$ 0.7
Number of impaired properties held for sale				1
Number of properties related to gain on sales			1	1	1