Schedule III- Real Estate and Accumulated Depreciation Schedule III - Real Estate and Accumulated Depreciation - Rollforward of Accumulated Depreciation (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate, Accumulated Depreciation [Roll Forward]
Balance as of the beginning of the year	$ 882,488	$ 734,783	$ 581,505
Additions	217,566	202,837	171,545
Dispositions	(15,006)	(55,132)	(18,267)
Balance as of the end of the year	1,085,048	882,488	734,783
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
Accumulated depreciation lease intangibles	$ 362,800	$ 325,700	$ 286,900
Tenant Improvements | Minimum
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
Estimated useful life	1 year
Tenant Improvements | Maximum
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
Estimated useful life	10 years
Furniture, fixtures and equipment
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
Estimated useful life	5 years