Intangible Assets and Liabilities - Intangible Assets and Liabilities (Details) - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Intangible Assets [Line Items]
Intangible Assets, Total Cost	$ 188,767	$ 196,417
Intangible Assets, Accumulated Amortization	(79,402)	(65,069)
Intangible Assets, net	109,365	131,348
Acquired Lease Intangibles, Net	27,958	31,783
Below market leases [Member]
Intangible Assets [Line Items]
Acquired Lease Intangibles, Gross	48,200	49,655
Acquired Lease Intangibles, Accumulated Amortization	(20,242)	(17,872)
Acquired Lease Intangibles, Net	27,958	31,783
In-place lease value [Member]
Intangible Assets [Line Items]
Intangible Assets, Total Cost	176,557	181,887
Intangible Assets, Accumulated Amortization	(69,371)	(53,376)
Intangible Assets, net	107,186	128,511
Tenant relationship value [Member]
Intangible Assets [Line Items]
Intangible Assets, Total Cost	7,244	9,564
Intangible Assets, Accumulated Amortization	(6,558)	(8,551)
Intangible Assets, net	686	1,013
Above market leases acquired [Member]
Intangible Assets [Line Items]
Intangible Assets, Total Cost	4,966	4,966
Intangible Assets, Accumulated Amortization	(3,473)	(3,142)
Intangible Assets, net	$ 1,493	$ 1,824