Intangible Assets - Intangible Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Intangible Assets [Line Items]
Intangible Assets, Total Cost	$ 160,681	$ 183,872
Intangible Assets, Accumulated Amortization	(88,203)	(72,249)
Intangible Assets, net	72,478	111,623
Acquired Lease Intangibles, Gross		48,956
Acquired Lease Intangibles, Accumulated Amortization		(23,301)
Acquired Lease Intangibles, Net	18,119	25,655
Below market leases [Member]
Intangible Assets [Line Items]
Acquired Lease Intangibles, Gross	37,579	50,025
Acquired Lease Intangibles, Accumulated Amortization	(19,460)	(24,178)
Acquired Lease Intangibles, Net	18,119	25,847
Liabilities of assets held for sale [Member]
Intangible Assets [Line Items]
Acquired Lease Intangibles, Gross		1,069
Acquired Lease Intangibles, Accumulated Amortization		(877)
Acquired Lease Intangibles, Net		192
In-place lease value [Member]
Intangible Assets [Line Items]
Intangible Assets, Total Cost	142,889	161,276
Intangible Assets, Accumulated Amortization	(75,696)	(57,063)
Intangible Assets, net	67,193	104,213
Tenant relationship value [Member]
Intangible Assets [Line Items]
Intangible Assets, Total Cost	13,074	20,117
Intangible Assets, Accumulated Amortization	(10,167)	(15,580)
Intangible Assets, net	2,907	4,537
Above market leases acquired [Member]
Intangible Assets [Line Items]
Intangible Assets, Total Cost	4,718	5,333
Intangible Assets, Accumulated Amortization	(2,340)	(1,879)
Intangible Assets, net	$ 2,378	3,454
Intangible assets including assets held for sale [Member]
Intangible Assets [Line Items]
Intangible Assets, Total Cost		186,726
Intangible Assets, Accumulated Amortization		(74,522)
Intangible Assets, net		112,204
Assets held for sale [Member]
Intangible Assets [Line Items]
Intangible Assets, Total Cost		2,854
Intangible Assets, Accumulated Amortization		(2,273)
Intangible Assets, net		$ 581