Acquired Intangible Assets and Liabilities (Schedule of Estimated Annual Amortization of Below Market Leases) (Details) - Below-Market Leases, Net of Above-Market Leases $ in Thousands	Jun. 30, 2018 USD ($)
Finite-Lived Intangible Assets [Line Items]
Remainder of 2018	$ (13,782)
2019	(16,399)
2020	(4,146)
2021	1,159
2022	8,243
Thereafter	91,361
Total	$ 66,436