Noncontrolling Interest (Details) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2021 USD ($)	Jun. 30, 2020 USD ($)	Jun. 30, 2021 USD ($) property	Jun. 30, 2020 USD ($)
Noncontrolling Interest
Net income attributable to noncontrolling interest	$ (1,577)	$ (1,330)	$ (2,899)	$ (2,738)
Cash distribution for joint venture partners	5,630	$ 5,616	11,324	$ 11,383
Variable interest entity, consolidated, carrying amount, real estate assets	695,287		695,287
Variable interest entity, consolidated, carrying amount, mortgage debt	$ 620,000		$ 620,000
Joint Venture
Noncontrolling Interest
Ownership percentage by noncontrolling owners	45.00%		45.00%
Ownership percentage	55.00%		55.00%
Boston, MA \| Life Science Building \| Joint Venture
Noncontrolling Interest
Number of properties included in joint venture agreement \| property			1

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