Document and Entity Information - shares	3 Months Ended
	Mar. 31, 2019	May 08, 2019
Document and Entity Information
Entity Registrant Name	SENIOR HOUSING PROPERTIES TRUST
Entity Central Index Key	0001075415
Document Type	10-Q
Document Period End Date	Mar. 31, 2019
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Entity Current Reporting Status	Yes
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding (in shares)		237,726,371
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	Q1
Entity Emerging Growth Company	false
Entity Smaller Reporting Company	false