Significant Accounting Policies (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Accounting Policies [Abstract]
Period in which the company capitalizes interest, real estate taxes and certain operating expenses on the unoccupied portion of recently completed properties, beginning with the date it is substantially complete (percent)	90.00%
Period in which the company capitalizes interest, real estate taxes and certain operating expenses on the unoccupied portion of recently completed properties, beginning with the date it is substantially complete (in years)	1 year
Revenue from External Customer [Line Items]
Revenues	$ 657,515	$ 475,212	$ 466,185
Deferred income	$ 52,269	41,266
Buildings | Minimum
Property, Plant and Equipment [Line Items]
Useful life	30 years
Buildings | Maximum
Property, Plant and Equipment [Line Items]
Useful life	42 years
Furniture, Fixtures and Equipment | Minimum
Property, Plant and Equipment [Line Items]
Useful life	3 years
Furniture, Fixtures and Equipment | Maximum
Property, Plant and Equipment [Line Items]
Useful life	5 years
Tenant Funded Improvements
Revenue from External Customer [Line Items]
Deferred income	$ 17,800	16,200
Tenants Expenses
Revenue from External Customer [Line Items]
Revenues	$ 122,400	$ 79,800	$ 67,200