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Related Person Transactions (Details) $ in Thousands	1 Months Ended	3 Months Ended		9 Months Ended
	Jun. 30, 2020 USD ($)	Sep. 30, 2020 USD ($) agreement shares	Sep. 30, 2019 USD ($)	Sep. 30, 2020 USD ($) agreement shares	Sep. 30, 2019 USD ($)	Dec. 31, 2019 USD ($)
Related person transactions
Proceeds from sale of equity method investments				$ 287	$ 0
Equity in earnings of an investee		$ 0	$ 83	$ 0	$ 617
Five Star
Related person transactions
Equity securities investment (in shares) | shares		10,691,658		10,691,658
Investment owned, percentage of total shares outstanding		33.90%		33.90%
RMR LLC
Related person transactions
Number of management agreements | agreement		2		2
AIC
Related person transactions
Equity method investments		$ 11		$ 11		$ 298
Proceeds from sale of equity method investments	$ 287
Equity in earnings of an investee		$ 83		617
Five Star
Related person transactions
Property insurance program costs				$ 500
RMR LLC | Five Star
Related person transactions
Investment owned, percentage of total shares outstanding		6.40%		6.40%

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