Subsequent Events	3 Months Ended
Subsequent Events	Mar. 31, 2023
Subsequent Events [Abstract]
Subsequent Events	Subsequent Events Pending Merger with Diversified Healthcare Trust On April 11, 2023, we and Diversified Healthcare Trust, or DHC, entered into an Agreement and Plan of Merger, or the Merger Agreement, pursuant to which, on the terms and subject to the satisfaction or waiver of the conditions thereof, DHC will be merged with and into us, with us continuing as the surviving entity in the merger, or the Merger. Pursuant to the terms and subject to the conditions and limitations set forth in the Merger Agreement, at the date and time the Merger becomes effective, or the Effective Time, each common share of beneficial interest, $0.01 par value per share, of DHC, or the DHC Common Shares, issued and outstanding as of immediately prior to the Effective Time will be automatically converted into the right to receive 0.147 (such ratio, the Exchange Ratio) of our common shares, subject to adjustment for certain reclassifications, distributions, recapitalizations or similar transactions and other exceptional distributions as described in the Merger Agreement, with cash paid in lieu of fractional shares. Other than as provided in the Merger Agreement, the Exchange Ratio is fixed and will not be adjusted to reflect changes in the market price of our common shares or the DHC Common Shares prior to the Effective Time. Our common shares issued and outstanding immediately prior to the Effective Time will remain issued and outstanding common shares of beneficial ownership of the surviving entity following the Merger. We expect to change our name from “Office Properties Income Trust” to “Diversified Properties Trust” at the Effective Time. The transactions contemplated by the Merger Agreement and the terms thereof were evaluated, negotiated and recommended to our Board of Trustees, or our Board, by a special committee of our Board, or the OPI Special Committee, and to DHC’s board of trustees, or the DHC Board, by a special committee of DHC’s Board, or the DHC Special Committee, each consisting of disinterested, independent trustees of us and DHC, respectively. Following the recommendations of the OPI Special Committee and the DHC Special Committee, our Board and the DHC Board each approved the Merger Agreement and the transactions contemplated thereby and resolved to recommend that the OPI and DHC shareholders, respectively, vote in favor of approval of the Merger and the transactions contemplated thereby. Our shareholders will be asked to vote on the approval of the Merger and related matters, including the issuance of our common shares in the Merger, at a special meeting of our shareholders. The consummation of the Merger is subject to the satisfaction or waiver of certain closing conditions, including, among others: (1) the approval of the Merger by the affirmative vote of at least a majority of all the votes entitled to be cast by holders of outstanding DHC Common Shares at the meeting held for that purpose; (2) the approval of the Merger by the affirmative vote of at least a majority of all the votes entitled to be cast by holders of our outstanding common shares at the meeting held for that purpose; (3) the approval of the issuance of our common shares to be issued in the Merger, or the Share Issuance, by the affirmative vote of at least a majority of all votes cast by holders of our outstanding common shares at the meeting held for that purpose; (4) the absence of any statute, rule or regulation by any governmental entity of competent jurisdiction or any temporary, preliminary or permanent judgment, order or decree by any court of competent jurisdiction which would prohibit or make illegal or prevent the consummation of the Merger or any of the transactions contemplated by the Merger Agreement; (5) the effectiveness of the registration statement on Form S-4, or the Form S-4, to be filed by us with the Securities and Exchange Commission, or the SEC, in connection with the Share Issuance; (6) the approval (subject to notice of issuance) of Nasdaq of the listing of our common shares to be issued in the Merger; (7) the extension or replacement of our existing revolving credit agreement, on terms that, among other things, would not be reasonably likely to be materially adverse to the business, operations or financial condition of us after giving effect to the Merger and would not delay or prevent the consummation of the Merger; (8) the receipt of certain tax opinions by us and DHC; and (9) the other party’s representations and warranties being accurate (subject to certain customary materiality exceptions) and the other party having performed or complied in all material respects with its agreements and covenants in the Merger Agreement. The Merger Agreement contains certain customary representations, warranties and covenants, including covenants providing that we and DHC will use reasonable best efforts to conduct our and its respective businesses in all material respects in the ordinary course during the period between the execution of the Merger Agreement and the earlier of the Effective Time or the termination of the Merger Agreement, and to refrain from taking certain types of actions without the other party’s consent during the period between the execution of the Merger Agreement and the earlier of the Effective Time or the termination of the Merger Agreement, subject in each case to specified exceptions. In connection with the execution of the Merger Agreement, we entered into a commitment letter, dated as of April 11, 2023, with JPMorgan Chase Bank, N.A., or JPM, pursuant to which JPM has committed to provide, subject to the terms and conditions of the commitment letter, a senior secured bridge facility to us in an aggregate principal amount of $368,000. Third Amended and Restated Property Management Agreement and Letter Agreement RMR serves as our and DHC’s manager and will continue to manage the surviving entity following the Merger. Contemporaneously with the execution of the Merger Agreement, on April 11, 2023, we and RMR entered into a Third Amended and Restated Property Management Agreement, or the Amended Property Management Agreement. The effectiveness of the Amended Property Management Agreement is conditioned upon and will be concurrent with the consummation of the Merger. If the Merger is not consummated, the Amended Property Management Agreement will not become effective and the Second Amended and Restated Property Management Agreement, or the Current Property Management Agreement, will remain in effect. Pursuant to the Amended Property Management Agreement, at the Effective Time properties currently owned by DHC that are subject to its existing property management agreement, including its medical office and life science properties, will become subject to the terms and conditions of the Amended Property Management Agreement. Also pursuant to the Amended Property Management Agreement, RMR will be entitled to a renovation and repositioning fee equal to 3% of the cost of any major capital projects and repositionings at senior living communities currently owned by DHC that the surviving entity may request RMR to oversee from time to time, consistent with DHC’s existing property management agreement with RMR. The terms of the Amended Property Management Agreement are otherwise consistent with the terms of the Current Property Management Agreement. In addition, contemporaneously with the execution of the Merger Agreement, we, DHC and RMR entered into a letter agreement, or the RMR Letter Agreement, pursuant to which, on the terms and subject to conditions contained therein, DHC and RMR have acknowledged and agreed that, effective upon consummation of the Merger, DHC shall have terminated its business and property management agreements with RMR for convenience, and RMR shall have waived its right to receive payment of the termination fee pursuant to each such agreement upon such termination. The foregoing terminations and waivers apply only in respect of the Merger and do not apply to any other transaction or arrangement.