Area Of Real Estate Property, Percentage Upon Completion Of Re-Development

No definition available.

Name:	opi_AreaOfRealEstatePropertyPercentageUponCompletionOfReDevelopment
Namespace Prefix:	opi_
Data Type:	dtr-types1:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Lessor, Operating Lease, Lease Not yet Commenced, Annual Base Rent

+ References

No definition available.

+ Details

Name:	opi_LessorOperatingLeaseLeaseNotYetCommencedAnnualBaseRent
Namespace Prefix:	opi_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Lessor, Operating Lease, Lease Not yet Commenced, Annual Base Rent Increase Period

+ References

No definition available.

+ Details

Name:	opi_LessorOperatingLeaseLeaseNotYetCommencedAnnualBaseRentIncreasePeriod
Namespace Prefix:	opi_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Lessor, Operating Lease, Lease Not yet Commenced, Annual Percentage Increase

+ References

No definition available.

+ Details

Name:	opi_LessorOperatingLeaseLeaseNotYetCommencedAnnualPercentageIncrease
Namespace Prefix:	opi_
Data Type:	dtr-types1:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Lessor, Operating Lease, Lease Not yet Commenced, Deferred Payment Plan Period

+ References

No definition available.

+ Details

Name:	opi_LessorOperatingLeaseLeaseNotYetCommencedDeferredPaymentPlanPeriod
Namespace Prefix:	opi_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Lessor, Operating Lease, Lease Not yet Commenced, Number Of Renewal Options

+ References

No definition available.

+ Details

Name:	opi_LessorOperatingLeaseLeaseNotYetCommencedNumberOfRenewalOptions
Namespace Prefix:	opi_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

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

+ References

No definition available.

+ Details

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

- Definition

Number Of Joint Ventures

+ References

No definition available.

+ Details

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

- Definition

Area of a real estate property.

+ References

No definition available.

+ Details

Name:	us-gaap_AreaOfRealEstateProperty
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:areaItemType
Balance Type:	na
Period Type:	instant

- Definition

Amount of lease income from operating, direct financing, and sales-type leases. Includes, but is not limited to, variable lease payments, interest income, profit (loss) recognized at commencement, and lease payments paid and payable to lessor.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 842
-SubTopic 30
-Name Accounting Standards Codification
-Section 50
-Paragraph 5
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479773/842-30-50-5

+ Details

Name:	us-gaap_LeaseIncome
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Term of lessor's operating lease renewal for lease not yet commenced, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 842
-SubTopic 30
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Subparagraph (a)(3)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479773/842-30-50-3

+ Details

Name:	us-gaap_LessorOperatingLeaseLeaseNotYetCommencedRenewalTerm1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	instant

- Definition

Term of lessor's operating lease not yet commenced, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

+ References

+ Details

Name:	us-gaap_LessorOperatingLeaseLeaseNotYetCommencedTermOfContract1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
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 946
-SubTopic 220
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.6-07(2)(c)(2)(i))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483575/946-220-S99-1

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 220
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.6-07(2)(c)(2)(ii))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483575/946-220-S99-1

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 220
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.6-07(2)(g)(3))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147483575/946-220-S99-1

+ Details

Name:	us-gaap_RelatedPartyTransactionLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Carrying amount as of the balance sheet date of improvements having a life longer than one year that were made for the benefit of one or more tenants.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 944
-SubTopic 210
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(a)(1)(d))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479440/944-210-S99-1

+ Details

Name:	us-gaap_TenantImprovements
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Details

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

- Details

Name:	srt_CounterpartyNameAxis=opi_ReitManagementAndResearchLLCMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_CounterpartyNameAxis=opi_SonestaInternationalHotelsCorporationMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Related Person Transactions (Details) $ in Thousands	1 Months Ended	3 Months Ended		9 Months Ended
Related Person Transactions (Details) $ in Thousands	Jun. 30, 2021 USD ($) ft² renewal_option	Sep. 30, 2023 USD ($)	Sep. 30, 2022 USD ($)	Sep. 30, 2023 USD ($) joint_venture agreement	Sep. 30, 2022 USD ($)
Related Party Transaction [Line Items]
Number of joint ventures \| joint_venture				2
Rental income		$ 133,361	$ 137,683	$ 399,780	$ 426,353
Related Party \| RMR LLC
Related Party Transaction [Line Items]
Number of agreements \| agreement				2
Rental income		205	$ 282	$ 671	$ 851
Related Party \| Sonesta
Related Party Transaction [Line Items]
Lessor, operating lease, lease not yet commenced, term of contract	30 years
Rentable square feet (in square feet) \| ft²	230,000
Area of real estate property percentage upon completion of re-development	55.00%
Number of renewal options \| renewal_option	2
Renewal term	10 years
Annual base rent	$ 6,436
Deferred payment plan period	18 months
Annual percentage increase	10.00%
Annual base rent increase period	5 years
Tenant improvements		$ 77,000		$ 77,000