Intangible Assets and Liabilities - Intangible Assets and Liabilities (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Intangible Assets [Line Items]
Intangible assets, total cost	$ 81,283	$ 94,173
Intangible assets, accumulated amortization	(46,769)	(45,603)
Intangible Assets, net	34,514	48,570
Intangible liabilities, total cost	28,881	31,263
Intangible liabilities, accumulated amortization	(14,430)	(12,815)
Intangible Liabilities, net	14,451	18,448
In-place lease value
Intangible Assets [Line Items]
Intangible assets, total cost	80,630	91,552
Intangible assets, accumulated amortization	(46,386)	(43,400)
Intangible Assets, net	34,244	48,152
Tenant relationship value
Intangible Assets [Line Items]
Intangible assets, total cost	167	2,091
Intangible assets, accumulated amortization	(95)	(1,938)
Intangible Assets, net	72	153
Above market leases acquired
Intangible Assets [Line Items]
Intangible assets, total cost	486	530
Intangible assets, accumulated amortization	(288)	(265)
Intangible Assets, net	$ 198	$ 265