Number Of Real Estate Properties, Under Agreement To Sell

No definition available.

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

- Definition

This element represents the aggregate sales price excluding closing costs, of real estate properties sold by the entity.

+ References

No definition available.

+ Details

Name:	opi_RealEstateAggregateSalesPrice
Namespace Prefix:	opi_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
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

The difference between the carrying value and the sale price of real estate or properties that were intended to be sold or held for capital appreciation or rental income. This element refers to the gain (loss) included in earnings and not to the cash proceeds of the sale. This element is a noncash adjustment to net income when calculating net cash generated by operating activities using the indirect method.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 230
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 28
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482740/230-10-45-28

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 360
-SubTopic 10
-Name Accounting Standards Codification
-Section 45
-Paragraph 5
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482130/360-10-45-5

Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 360
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482099/360-10-50-3

+ Details

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

- Definition

The charge against earnings in the period to reduce the carrying amount of real property to fair value.

+ References

+ Details

Name:	us-gaap_ImpairmentOfRealEstate
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The number of real estate properties owned as of the balance sheet date.

+ References

No definition available.

+ Details

Name:	us-gaap_NumberOfRealEstateProperties
Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
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

No definition available.

+ Details

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

- Details

Name:	srt_StatementGeographicalAxis=opi_TempeAZMember
Namespace Prefix:
Data Type:	na
Balance Type:
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- Details

Name:	us-gaap_SubsequentEventTypeAxis=us-gaap_SubsequentEventMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DisposalGroupClassificationAxis=us-gaap_DisposalGroupDisposedOfBySaleNotDiscontinuedOperationsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_StatementGeographicalAxis=opi_ParsippanyNJMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_StatementGeographicalAxis=opi_SantaClaraCAMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_StatementGeographicalAxis=opi_DetroitMIMember
Namespace Prefix:
Data Type:	na
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Period Type:

- Details

Name:	us-gaap_DisposalGroupClassificationAxis=us-gaap_DisposalGroupHeldForSaleOrDisposedOfBySaleNotDiscontinuedOperationsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_StatementGeographicalAxis=opi_RestonVAMember
Namespace Prefix:
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Real Estate Properties - Disposition Activities (Details) ft² in Thousands, $ in Thousands		1 Months Ended	3 Months Ended		9 Months Ended
	Sep. 30, 2025 USD ($) ft² property	Dec. 31, 2025 USD ($)	Sep. 30, 2025 USD ($) ft² property	Sep. 30, 2024 USD ($)	Sep. 30, 2025 USD ($) ft² property	Sep. 30, 2024 USD ($)
Real Estate Properties [Line Items]
Gain (Loss) on Sale of Real Estate			$ 6	$ 8,456	$ (4,572)	$ 6,008
Loss on Impairment of Real Estate			$ 0	$ 41,847	$ 2,426	$ 173,579
Tempe, AZ \| Subsequent Event
Real Estate Properties [Line Items]
Gross Sales Price		$ 11,038
Disposal Group, Disposed of by Sale, Not Discontinued Operations
Real Estate Properties [Line Items]
Number of Properties \| property	4		4		4
Rentable Square Feet \| ft²	305		305		305
Gross Sales Price					$ 29,050
Gain (Loss) on Sale of Real Estate					(4,572)
Loss on Impairment of Real Estate					$ (2,426)
Disposal Group, Disposed of by Sale, Not Discontinued Operations \| Parsippany, NJ
Real Estate Properties [Line Items]
Number of Properties \| property	1		1		1
Rentable Square Feet \| ft²	100		100		100
Gross Sales Price					$ 5,750
Gain (Loss) on Sale of Real Estate					(4,641)
Loss on Impairment of Real Estate					$ 0
Disposal Group, Disposed of by Sale, Not Discontinued Operations \| Santa Clara, CA
Real Estate Properties [Line Items]
Number of Properties \| property	2		2		2
Rentable Square Feet \| ft²	149		149		149
Gross Sales Price					$ 21,150
Gain (Loss) on Sale of Real Estate					42
Loss on Impairment of Real Estate					$ 0
Disposal Group, Disposed of by Sale, Not Discontinued Operations \| Detroit, MI
Real Estate Properties [Line Items]
Number of Properties \| property	1		1		1
Rentable Square Feet \| ft²	56		56		56
Gross Sales Price					$ 2,150
Gain (Loss) on Sale of Real Estate					27
Loss on Impairment of Real Estate					$ (2,426)
Disposal Group, Held-for-Sale or Disposed of by Sale, Not Discontinued Operations
Real Estate Properties [Line Items]
Number of Properties \| property	3		3		3
Number of Properties, under agreement to sell \| property	3		3		3
Rentable Square Feet \| ft²	376		376		376
Gross Sales Price	$ 28,863
Disposal Group, Held-for-Sale or Disposed of by Sale, Not Discontinued Operations \| Tempe, AZ
Real Estate Properties [Line Items]
Number of Properties, under agreement to sell \| property	2		2		2
Rentable Square Feet \| ft²	101		101		101
Gross Sales Price	$ 10,738
Disposal Group, Held-for-Sale or Disposed of by Sale, Not Discontinued Operations \| Reston, VA
Real Estate Properties [Line Items]
Number of Properties, under agreement to sell \| property	1		1		1
Rentable Square Feet \| ft²	275		275		275
Gross Sales Price	$ 18,125