Property Dispositions, Assets Held for Sale, and Discontinued Operations (Assets Held-for-Sale) (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]
Total other assets held for sale, net	$ 10,222	$ 9,815
Disposal Group, Held-for-sale, Not Discontinued Operations [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Total real estate assets held for sale, net	225,071	225,939
Straight-line rent receivables	2,225	2,059
Prepaid expenses and other assets	762	454
Deferred lease costs, less accumulated amortization of $2,892 and $2,825 as of June 30, 2017 and December 31, 2016, respectively	7,235	7,302
Accumulated amortization on deferred lease costs	2,892	2,825
Total other assets held for sale, net	10,222	9,815
Disposal Group, Held-for-sale, Not Discontinued Operations [Member] | Land [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Real estate assets held for sale, net:	52,710	52,710
Disposal Group, Held-for-sale, Not Discontinued Operations [Member] | Building and building improvements [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Real estate assets held for sale, net:	172,350	173,218
Accumulated depreciation (building improvements)	89,187	88,319
Disposal Group, Held-for-sale, Not Discontinued Operations [Member] | Construction in Progress [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Real estate assets held for sale, net:	$ 11	$ 11