Intangible Assets and Liabilities - Intangible Assets and Liabilities (Details) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Intangible Assets [Line Items]
Intangible assets, total cost	$ 97,319	$ 177,581
Intangible assets, accumulated amortization	(42,057)	(92,730)
Intangible assets, net	55,262	84,851
Intangible liabilities, net	29,526	44,757
Acquired lease intangibles, accumulated amortization	(10,949)	(22,494)
Acquired lease intangibles, net	18,577	22,263
In-place lease value
Intangible Assets [Line Items]
Intangible assets, total cost	144,957	167,357
Intangible assets, accumulated amortization	(78,187)	(84,123)
Intangible assets, net	66,770	83,234
Tenant relationship value
Intangible Assets [Line Items]
Intangible assets, total cost	5,142	5,268
Intangible assets, accumulated amortization	(4,859)	(4,815)
Intangible assets, net	283	453
Above market leases acquired
Intangible Assets [Line Items]
Intangible assets, total cost	4,685	4,956
Intangible assets, accumulated amortization	(3,979)	(3,792)
Intangible assets, net	706	$ 1,164
Not Held for Sale
Intangible Assets [Line Items]
Intangible assets, total cost	154,784
Intangible assets, accumulated amortization	(87,025)
Intangible assets, net	67,759
Acquired lease intangibles, net	19,190
Held-for-sale
Intangible Assets [Line Items]
Intangible assets, total cost	57,465
Intangible assets, accumulated amortization	(44,968)
Intangible assets, net	12,497
Intangible liabilities, net	5,225
Acquired lease intangibles, accumulated amortization	(4,612)
Acquired lease intangibles, net	613
Below market leases acquired
Intangible Assets [Line Items]
Intangible liabilities, net	34,751
Acquired lease intangibles, accumulated amortization	(15,561)
Acquired lease intangibles, net	$ 19,190