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	Sep. 30, 2018 USD ($)
Finite-Lived Intangible Assets [Line Items]
Remainder of 2018	$ (6,690)
2019	(16,127)
2020	(3,902)
2021	899
2022	7,932
Thereafter	90,963
Total	$ 73,075