Intangible Assets and Liabilities - Intangible Assets and Liabilities (Details) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Intangible Assets [Line Items]
Intangible Assets, Total Cost	$ 131,935	$ 160,681
Intangible Assets, Accumulated Amortization	(67,713)	(88,203)
Intangible Assets, net	64,222	72,478
Acquired Lease Intangibles, Net	16,604	18,119
Below market leases [Member]
Intangible Assets [Line Items]
Acquired Lease Intangibles, Gross	30,683	37,579
Acquired Lease Intangibles, Accumulated Amortization	(14,079)	(19,460)
Acquired Lease Intangibles, Net	16,604	18,119
In-place lease value [Member]
Intangible Assets [Line Items]
Intangible Assets, Total Cost	114,196	142,889
Intangible Assets, Accumulated Amortization	(54,834)	(75,696)
Intangible Assets, net	59,362	67,193
Tenant relationship value [Member]
Intangible Assets [Line Items]
Intangible Assets, Total Cost	13,036	13,074
Intangible Assets, Accumulated Amortization	(10,378)	(10,167)
Intangible Assets, net	2,658	2,907
Above market leases acquired [Member]
Intangible Assets [Line Items]
Intangible Assets, Total Cost	4,703	4,718
Intangible Assets, Accumulated Amortization	(2,501)	(2,340)
Intangible Assets, net	$ 2,202	$ 2,378