Discontinued Operations and Assets Held for Sale (Aggregate Balance Sheet of Properties Held for Sale Included in Discontinued Operations) (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2016 USD ($) a buildings	Dec. 31, 2015 USD ($)
Held for Sale Assets in Continuing and Discontinued Operations
Total assets held-for-sale	$ 18,184	$ 45,801
Total liabilities held-for-sale	$ 238	972
Continuing Operations, Number of In-service Properties Held for Sale | buildings	1
Area of Land | a	14
Continuing Operations [Member]
Held for Sale Assets in Continuing and Discontinued Operations
Land and Land Improvements Held-for-Sale	$ 5,142	9,797
Buildings and Tenant Improvements Held-for-Sale	6,032	39,480
Inventory, Land Held-for-sale	9,939	0
Accumulated Depreciation of Assets Held-for-Sale	(3,763)	(7,183)
Lease Related Assets, Held for Sale	419	3,293
Other assets	415	414
Total assets held-for-sale	18,184	45,801
Accrued expenses	150	322
Other liabilities	88	650
Total liabilities held-for-sale	$ 238	$ 972