Business and Property Management Agreements with RMR LLC (Details) - RMR LLC $ in Thousands	3 Months Ended	12 Months Ended
Mar. 31, 2021 USD ($) agreement employee	Mar. 31, 2020 USD ($)	Dec. 31, 2020 USD ($)
Related Party Transaction [Line Items]
Number of employees \| employee	0
Number of agreements \| agreement	2
Incentive fee	$ 5,200	$ 0	$ 0
Reimbursement expense	6,052	5,991
Net Property Management and Construction Supervision Fees
Related Party Transaction [Line Items]
Related party expense	9,474	4,699
Related party transaction amount	4,612	5,064
Net Property Management and Construction Supervision Fees \| Buildings and Improvements
Related Party Transaction [Line Items]
Related party transaction amount	532	656
Net Property Management and Construction Supervision Fees \| Other Operating Income (Expense)
Related Party Transaction [Line Items]
Related party transaction amount	$ 4,080	$ 4,408

Represents the number of agreements with RMR LLC to provide management services to the company.

No definition available.

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- Definition

Represents the number of employees in the company.

+ References

No definition available.

+ Details

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- Definition

Total expense amount to reimburse a related party.

+ References

No definition available.

+ Details

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- Definition

Amount of expense for incentive rights held by the managing member or general partner, of limited liability company (LLC) or limited partnership (LP).

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 850
-SubTopic 10
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6457730&loc=d3e39549-107864

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- Definition

Amount of transactions with related party during the financial reporting period.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 850
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (c)
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Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
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-Topic 850
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-Section 50
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-URI http://asc.fasb.org/extlink&oid=6457730&loc=d3e39603-107864

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- Definition

Expenses recognized resulting from transactions (excluding transactions that are eliminated in consolidated or combined financial statements) with related party.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 850
-SubTopic 10
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-URI http://asc.fasb.org/extlink&oid=6457730&loc=d3e39549-107864

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

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