Related Person Transactions - RMR Office Property Fund LP (Details) - Open End Fund $ in Thousands	Jul. 28, 2020 USD ($)	Aug. 31, 2018 USD ($) property
RMR LLC
Related Party Transaction [Line Items]
Committed capital	$ 100,000	$ 100,000
ABP Trust
Related Party Transaction [Line Items]
Number of properties contributed \| property		15
Value of property contributed		$ 206,300

Value of property contributed in noncash investing and financing activities.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
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Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
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