Discontinued Operations and Assets Held for Sale (Aggregate Balance Sheet of Properties Held for Sale Included in Discontinued Operations) (Details) $ in Thousands	6 Months Ended
	Jun. 30, 2016 USD ($) a buildings	Dec. 31, 2015 USD ($)
Held for Sale Assets in Continuing and Discontinued Operations
Total assets held-for-sale	$ 3,462	$ 45,801
Total liabilities held-for-sale	$ 645	972
Continuing Operations, Number of In-service Properties Held for Sale | buildings	1
Area of Land | a	16
Continuing Operations [Member]
Held for Sale Assets in Continuing and Discontinued Operations
Land and Land Improvements Held-for-Sale	$ 603	9,797
Buildings and Tenant Improvements Held-for-Sale	3,329	39,480
Inventory, Land Held-for-sale	596	0
Accumulated Depreciation of Assets Held-for-Sale	(1,437)	(7,183)
Lease Related Assets, Held for Sale	11	3,293
Other assets	360	414
Total assets held-for-sale	3,462	45,801
Accrued expenses	43	322
Other liabilities	602	650
Total liabilities held-for-sale	$ 645	$ 972