Basis of Presentation	6 Months Ended
Jun. 30, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Presentation	Basis of Presentation The accompanying condensed consolidated financial statements of Senior Housing Properties Trust and its subsidiaries, or we, us, or our, are unaudited. Certain information and disclosures required by U.S. generally accepted accounting principles, or GAAP, for complete financial statements have been condensed or omitted. We believe the disclosures made are adequate to make the information presented not misleading. However, the accompanying condensed consolidated financial statements should be read in conjunction with the consolidated financial statements and notes contained in our Annual Report on Form 10-K for the year ended December 31, 2017, or our Annual Report. In the opinion of management, all adjustments (consisting of normal recurring accruals) considered necessary for a fair statement of results for the interim period have been included. All intercompany transactions and balances with or among our consolidated subsidiaries have been eliminated. Operating results for interim periods are not necessarily indicative of the results that may be expected for the full year. The preparation of financial statements in conformity with GAAP requires us to make estimates and assumptions that affect reported amounts. Actual results could differ from those estimates. Significant estimates in our condensed consolidated financial statements include purchase price allocations, useful lives of fixed assets and impairment of real estate and intangible assets. In March 2017, we entered a joint venture with a sovereign investor for one of our properties leased to medical providers, medical related business, clinics and biotech laboratory tenants, or MOBs (two buildings), located in Boston, Massachusetts. We have determined that this joint venture is a variable interest entity, or VIE, as defined under the Consolidation Topic of the Financial Accounting Standards Board, or FASB, Accounting Standards Codification. We concluded that we must consolidate this VIE because we have the power to direct the activities that most significantly impact the VIE’s economic performance and we have the obligation to absorb losses of, and the right to receive benefits from, the VIE that could be significant to the VIE, and therefore are the primary beneficiary of the VIE. The assets of this VIE were $1,080,268 and $1,102,986 as of June 30, 2018 and December 31, 2017, respectively, and consist primarily of the net real estate owned by the joint venture. The liabilities of this VIE were $716,127 and $720,678 as of June 30, 2018 and December 31, 2017, respectively, and consist primarily of the debt securing the property. The sovereign investor's interest in this consolidated entity is reflected as noncontrolling interest in our condensed consolidated financial statements. See Note 6 for further information about this joint venture.

Basis of Presentation

The accompanying condensed consolidated financial statements of Senior Housing Properties Trust and its subsidiaries, or we, us, or our, are unaudited. Certain information and disclosures required by U.S. generally accepted accounting principles, or GAAP, for complete financial statements have been condensed or omitted. We believe the disclosures made are adequate to make the information presented not misleading. However, the accompanying condensed consolidated financial statements should be read in conjunction with the consolidated financial statements and notes contained in our Annual Report on Form 10-K for the year ended December 31, 2017, or our Annual Report.

In the opinion of management, all adjustments (consisting of normal recurring accruals) considered necessary for a fair statement of results for the interim period have been included. All intercompany transactions and balances with or among our consolidated subsidiaries have been eliminated. Operating results for interim periods are not necessarily indicative of the results that may be expected for the full year.

The preparation of financial statements in conformity with GAAP requires us to make estimates and assumptions that affect reported amounts. Actual results could differ from those estimates. Significant estimates in our condensed consolidated financial statements include purchase price allocations, useful lives of fixed assets and impairment of real estate and intangible assets.

In March 2017, we entered a joint venture with a sovereign investor for one of our properties leased to medical providers, medical related business, clinics and biotech laboratory tenants, or MOBs (two buildings), located in Boston, Massachusetts. We have determined that this joint venture is a variable interest entity, or VIE, as defined under the Consolidation Topic of the Financial Accounting Standards Board, or FASB, Accounting Standards Codification. We concluded that we must consolidate this VIE because we have the power to direct the activities that most significantly impact the VIE’s economic performance and we have the obligation to absorb losses of, and the right to receive benefits from, the VIE that could be significant to the VIE, and therefore are the primary beneficiary of the VIE. The assets of this VIE were $1,080,268 and $1,102,986 as of June 30, 2018 and December 31, 2017, respectively, and consist primarily of the net real estate owned by the joint venture. The liabilities of this VIE were $716,127 and $720,678 as of June 30, 2018 and December 31, 2017, respectively, and consist primarily of the debt securing the property. The sovereign investor's interest in this consolidated entity is reflected as noncontrolling interest in our condensed consolidated financial statements. See Note 6 for further information about this joint venture.