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Senior Living Community Management Agreements - Narrative (Details) $ in Thousands			1 Months Ended	12 Months Ended
	Oct. 31, 2022 USD ($)	Jun. 09, 2021 USD ($) community unit	Dec. 31, 2023 USD ($) property unit	Dec. 31, 2023 USD ($) community property option unit	Dec. 31, 2022 USD ($) community	Dec. 31, 2021 USD ($) community unit
Concentration Risk
Number of properties owned (property) \| property			371	371
Senior Living Communities
Concentration Risk
Number of units in real estate property \| unit			27,271	27,271
Related Party \| Five Star
Concentration Risk
Management fees as a percentage of gross revenues			5.00%	5.00%
Percentage of annual incentive fee			15.00%	15.00%
Consumer price index annual estimated increase			2.00%	2.00%
Trigger basis for capital investment ratio (percent)			6.00%	6.00%
Business and property management agreement, number of agreements \| option				2
Renewal term (years)				5 years
Expenses from property management agreement transactions with related party				$ 40,119	$ 37,037	$ 47,479
Related party transaction capitalized amount				2,683	3,300	3,615
Related Party \| Five Star \| Property Operating Expense
Concentration Risk
Expenses from property management agreement transactions with related party				$ 37,436	$ 33,737	$ 43,864
Related Party \| Five Star \| Senior Living Communities
Concentration Risk
Number of properties owned (property) \| community		120
Number of real estate properties managed \| community		119
Related party transactions, termination percentage		10.00%
Percentage of EBITDA threshold for contract termination		80.00%
Number of communities managed \| community				119	119	120
Related Party \| Third Party Managers
Concentration Risk
Management fees payable to third parties				$ 21,863	$ 20,739	$ 6,239
Related Party \| Third Party Managers \| Senior Living Communities
Concentration Risk
Management agreement, extension term				2 years
Number of communities managed \| community				113	111	107
Termination fees paid			$ 1,000
Management agreement, term				5 years
Related Party \| Third Party Managers \| Senior Living Communities \| Minimum
Concentration Risk
Management fees as a percentage of gross revenues			5.00%	5.00%
Percentage of annual incentive fee			15.00%	15.00%
Construction supervision fee			3.00%	3.00%
Property management agreement, management fees			70.00%	70.00%
Related Party \| Third Party Managers \| Senior Living Communities \| Maximum
Concentration Risk
Management fees as a percentage of gross revenues			6.00%	6.00%
Percentage of annual incentive fee			25.00%	25.00%
Construction supervision fee			5.00%	5.00%
Property management agreement, management fees			80.00%	80.00%
Five Star Management \| Related Party
Concentration Risk
Termination fees paid	$ 350
Five Star Management \| Related Party \| Five Star
Concentration Risk
Management agreement, extension term		2 years
Rehabilitation Services \| Related Party \| Five Star \| Senior Living Communities
Concentration Risk
Amounts of transaction				$ 1,213	$ 6,289	$ 11,233
Disposal Group, Held-for-sale, Not Discontinued Operations \| Related Party \| Five Star \| Senior Living Communities
Concentration Risk
Number of properties owned (property) \| community		108				108
Number of units in real estate property \| unit		1,500
Amounts of transaction		$ 682,000
Disposal Group, Disposed of by Means Other than Sale, Not Discontinued Operations \| Related Party \| Five Star \| Senior Living Communities
Concentration Risk
Number of units in real estate property \| unit						7,340
Amounts of transaction				$ 0	$ 2,096	$ 17,363
Number of properties transitioned \| community						107
Scenario, Adjustment \| Disposal Group, Held-for-sale, Not Discontinued Operations \| Related Party \| Five Star \| Senior Living Communities
Concentration Risk
Number of units in real estate property \| unit		7,500