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

No definition available.

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Namespace Prefix:	opi_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the number of employees in the company.

+ References

No definition available.

+ Details

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Namespace Prefix:	opi_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of expense for incentive fee based on performance under arrangement to manage operations, including, but not limited to, investment.

+ References

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+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 210
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-Section S99
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+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- 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

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 310
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+ Details

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Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	us-gaap_LongtermDebtTypeAxis=us-gaap_LineOfCreditMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RelatedPartyTransactionsByRelatedPartyAxis=opi_ReitManagementAndResearchLLCMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Business and Property Management Agreements with RMR - Narrative (Details) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2025 USD ($) agreement employee	Dec. 31, 2024 USD ($)	Jan. 31, 2025 USD ($)
Line of Credit
Related Party Transaction [Line Items]
Maximum borrowing capacity on revolving credit facility			$ 100,000
RMR LLC
Related Party Transaction [Line Items]
Number of employees \| employee	0
Number of agreements \| agreement	2
Incentive fee	$ 0	$ 0