Related Person Transactions	9 Months Ended
Related Person Transactions	Sep. 30, 2021
Related Party Transactions [Abstract]
Related Person Transactions	Related Person Transactions We have relationships and historical and continuing transactions with RMR LLC, The RMR Group Inc., or RMR Inc., Five Star and others related to them, including other companies to which RMR LLC or its subsidiaries provide management services and some of which have trustees, directors or officers who are also our Trustees or officers. RMR Inc. is the managing member of RMR LLC. The Chair of our Board and one of our Managing Trustees, Adam D. Portnoy, is the sole trustee, an officer and the controlling shareholder of ABP Trust, which is the controlling shareholder of RMR Inc., a managing director and the president and chief executive officer of RMR Inc., an officer and employee of RMR LLC and the chair of the board of directors and a managing director of Five Star. Jennifer F. Francis, our other Managing Trustee and our President and Chief Executive Officer is an executive vice president of RMR Inc. and she and our Chief Financial Officer and Treasurer are also employees and officers of RMR LLC. Jennifer B. Clark, our Secretary and former Managing Trustee, also serves as a managing director and the executive vice president, general counsel and secretary of RMR Inc., an officer and employee of RMR LLC, an officer of ABP Trust and a managing director and the secretary of Five Star. Certain of Five Star's officers are officers and employees of RMR LLC. Some of our Independent Trustees also serve as independent trustees or independent directors of other public companies to which RMR LLC or its subsidiaries provide management services. Adam Portnoy serves as the chair of the boards of trustees or boards of directors and as a managing trustee or managing director of those companies. Other officers of RMR LLC, including Ms. Clark and certain of our officers, serve as managing trustees, managing directors or officers of certain of these companies. In addition, officers of RMR LLC and RMR Inc. serve as our officers and officers of other companies to which RMR LLC or its subsidiaries provide management services. See Note 7 for information relating to the annual share awards we made in September 2021 to our officers and certain other employees of RMR LLC and common shares we purchased from our officers and certain current and former officers and employees of RMR LLC in satisfaction of tax withholding and payment obligations in connection with the vesting of awards of our common shares to them. We include amounts recognized as expense for share awards to RMR LLC employees in general and administrative expenses in our condensed consolidated statements of comprehensive income (loss). Five Star. We are currently Five Star's largest stockholder. As of September 30, 2021, we owned 10,691,658 Five Star common shares, or approximately 33.7% of Five Star's outstanding common shares. Five Star manages certain of the senior living communities we own. RMR LLC provides management services to both us and Five Star. See Note 9 for further information regarding our relationships, agreements and transactions with Five Star and Note 5 for further information regarding our investment in Five Star. As of September 30, 2021, ABP Acquisition LLC, a subsidiary of ABP Trust, the controlling shareholder of RMR Inc., together with ABP Trust, owned approximately 6.4% of Five Star's outstanding common shares. Our Manager, RMR LLC. We have two agreements with RMR LLC to provide management services to us. See Note 10 for further information regarding our management agreements with RMR LLC. For further information about these and other such relationships and certain other related person transactions, see our Annual Report.