Number Of Joint Ventures

No definition available.

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

- Definition

Represents number of leases executed during the reporting period.

+ References

No definition available.

+ Details

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

- Definition

Number of Real Estate Properties Sold

+ References

No definition available.

+ Details

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

- Definition

Represents committed expenditures for operating leases executed during the period.

+ References

No definition available.

+ Details

Name:	opi_OperatingLeasesCommittedExpendituresOnLeasesExecutedInPeriod
Namespace Prefix:	opi_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Represents the area of leased property related to operating leases executed during the period.

+ References

No definition available.

+ Details

Name:	opi_OperatingLeasesCommittedExpendituresOnLeasesExecutedInPeriodAreaOfLeasedProperty
Namespace Prefix:	opi_
Data Type:	dtr-types:areaItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents committed but unspent tenant related obligations based on executed operating leases as of the balance sheet date.

+ References

No definition available.

+ Details

Name:	opi_OperatingLeasesCommittedExpendituresOnLeasesExecutedInPeriodCommittedButUnspentTenantRelatedObligations
Namespace Prefix:	opi_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Represents the weighted average lease term of operating leases.

+ References

No definition available.

+ Details

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

- 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 percentage of ownership of common stock or equity participation in the investee accounted for under the equity method of accounting.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 323
-SubTopic 10
-Section 50
-Paragraph 3
-Subparagraph (a)(1)
-URI http://asc.fasb.org/extlink&oid=114001798&loc=d3e33918-111571

+ Details

Name:	us-gaap_EquityMethodInvestmentOwnershipPercentage
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant

- 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

Carrying amount as of the balance sheet date of investments in land and buildings held for sale, excluding real estate considered to be inventory of the entity.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03.1(f))
-URI http://asc.fasb.org/extlink&oid=120400017&loc=d3e572229-122910

+ Details

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

- Definition

Amount of real estate investment property which may include the following: (1) land available-for-sale; (2) land available-for-development; (3) investments in building and building improvements; (4) tenant allowances; (5) developments in-process; (6) rental properties; and (7) other real estate investments.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03.1(d))
-URI http://asc.fasb.org/extlink&oid=120400017&loc=d3e572229-122910

+ Details

Name:	us-gaap_RealEstateInvestmentPropertyAtCost
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
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:	us-gaap_StatementOperatingActivitiesSegmentAxis=us-gaap_SegmentContinuingOperationsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RealEstatePropertiesAxis=us-gaap_UnconsolidatedPropertiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis=opi_JointVentureProperty1Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis=opi_JointVentureProperty2Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

- 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_KansasCityMOMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Real Estate Properties - Narrative (Details) ft² in Thousands, $ in Thousands		12 Months Ended
	Feb. 15, 2022 USD ($) ft² property	Dec. 31, 2021 USD ($) ft² joint_venture property lease	Dec. 31, 2020 USD ($) ft² property	Dec. 31, 2019 USD ($) ft² property
Real Estate Properties [Line Items]
Number of properties (in properties) \| property		178
Area of properties (in square feet) \| ft²		926	163
Real estate aggregate undepreciated carrying value		$ 3,911,086	$ 3,522,143
Number of joint ventures \| joint_venture		2
Number of leases entered \| lease		85
Rentable square feet (in sqft) \| ft²		2,484
Weighted average lease term		9 years 6 months
Expenditures committed on leases		$ 142,318
Operating leases committed expenditures on leases executed in period committed but unspent tenant related obligations		$ 121,754
Continuing Operations
Real Estate Properties [Line Items]
Area of properties (in square feet) \| ft²		23,271
Real estate aggregate undepreciated carrying value		$ 3,938,876
Unconsolidated Joint Ventures
Real Estate Properties [Line Items]
Number of properties (in properties) \| property		3
Area of properties (in square feet) \| ft²		444
Number of joint ventures \| joint_venture		2
Joint Venture Property 1
Real Estate Properties [Line Items]
Percentage of ownership interest		51.00%
Joint Venture Property 2
Real Estate Properties [Line Items]
Percentage of ownership interest		50.00%
Disposal Group, Held-for-sale, Not Discontinued Operations
Real Estate Properties [Line Items]
Number of properties (in properties) \| property		4
Area of properties (in square feet) \| ft²		330
Gross Sales Price, excluding closing costs		$ 29,545
Disposal Group, Held-for-sale, Not Discontinued Operations \| Subsequent Event
Real Estate Properties [Line Items]
Number of properties (in properties) \| property	1
Area of properties (in square feet) \| ft²	29
Gross Sales Price, excluding closing costs	$ 3,850
Disposal Group, Held-for-sale, Not Discontinued Operations \| Continuing Operations
Real Estate Properties [Line Items]
Carrying value		$ 27,790
Disposal Group, Disposed of by Sale
Real Estate Properties [Line Items]
Number of real estate properties sold (in properties) \| property			10	58
Number of properties (in properties) \| property			10	58
Area of properties (in square feet) \| ft²			906	6,179
Gross Sales Price, excluding closing costs			$ 110,463	$ 848,853
Disposal Group, Disposed of by Sale \| Kansas City, MO
Real Estate Properties [Line Items]
Number of real estate properties sold (in properties) \| property		6