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 entities to whom related party provides management services.

+ References

No definition available.

+ Details

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Namespace Prefix:	opi_
Data Type:	xbrli:integerItemType
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- Definition

This element represents the aggregate cost of investments accounted for under the equity method of accounting.

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- Definition

Amount of income (loss) for proportionate share of equity method investee's income (loss).

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Balance Type:	credit
Period Type:	duration

- Definition

The cash inflow from the issuance of common stock, preferred stock, treasury stock, stock options, and other types of equity.

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Balance Type:	debit
Period Type:	duration

- 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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- Definition

Amount of revenue, fees and commissions earned from transactions between (a) a parent company and its subsidiaries; (b) subsidiaries of a common parent; (c) an entity and trusts for the benefit of employees, for example, but not limited to, pension and profit-sharing trusts that are managed by or under the trusteeship of the entity's management; (d) an entity and its principal, owners, management, or members of their immediate families; and (e) affiliates.

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- Definition

Per share amount received by subsidiary or equity investee for each share of common stock issued or sold in the stock transaction.

+ References

No definition available.

+ Details

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Balance Type:	na
Period Type:	instant

- Definition

Cumulative number of shares issued or sold by the subsidiary or equity method investee on all stock transactions.

+ References

No definition available.

+ Details

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Related Person Transactions (Details) $ / shares in Units, $ in Thousands		3 Months Ended		9 Months Ended
	Jul. 01, 2019 USD ($) $ / shares	Sep. 30, 2019 USD ($) company	Sep. 30, 2018 USD ($)	Sep. 30, 2019 USD ($) company agreement shares	Sep. 30, 2018 USD ($)	Dec. 31, 2018 USD ($)
Related Party Transaction [Line Items]
Proceeds from sale of RMR Inc. common shares, net				$ 104,674	$ 0
Equity in net income (loss) of investees		$ (196)	$ 94	$ (573)	(1,112)
RMR LLC
Related Party Transaction [Line Items]
Number of agreements \| agreement				2
Revenue from related party		$ 288	263	$ 854	763
AIC
Related Party Transaction [Line Items]
Number of entities to whom services are provided \| company		5		5
Carrying value of equity method investments		$ 9,459		$ 9,459		$ 8,751
Equity in net income (loss) of investees		$ 83	$ 831	$ 617	$ 882
Underwritten public offering
Related Party Transaction [Line Items]
Price per share (in dollars per share) \| $ / shares	$ 40.00
Proceeds from sale of RMR Inc. common shares, net	$ 104,674
Underwritten public offering \| Class A common shares
Related Party Transaction [Line Items]
Shares holding (in shares) \| shares				2,801,060