Combined Guarantor Subsidiaries - Summary of Significant Accounting Policies - Intangibles and Balance Sheet Classifications (Details) - Guarantor Subsidiaries - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Accounts payable and accrued liabilities:
Cost	$ 27,831	$ 28,942
Accumulated Amortization	(22,729)	(21,805)
Above-market leases
Intangible lease assets and other assets:
Cost	11,522	12,307
Accumulated Amortization	(10,813)	(11,198)
In-place leases
Intangible lease assets and other assets:
Cost	42,905	46,229
Accumulated Amortization	(36,724)	(37,381)
Tenant relationships
Intangible lease assets and other assets:
Cost	26,068	27,866
Accumulated Amortization	$ (4,492)	$ (4,880)

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