Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

No definition available.

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- Definition

For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 275
-SubTopic 10
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- Definition

Amount of real estate investment property which may include the following: (1) land available-for-sale; (2) land available-for-development; (3) investments in building and building improvements; (4) tenant allowances; (5) developments in-process; (6) rental properties; and (7) other real estate investments.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03.1(d))
-URI http://asc.fasb.org/extlink&oid=119400593&loc=d3e572229-122910

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- Definition

Amount, excluding tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value added and excise.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 4
-Subparagraph (a)
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-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=118956577&loc=SL49130545-203045

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Leases and Management Agreements with Five Star - Schedule of Assets Leased and Revenues Earned (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Concentration Risk [Line Items]
Gross Book Value of Real Estate Assets	$ 7,461,586				$ 7,876,300				$ 7,461,586	$ 7,876,300
Total revenues	256,039	$ 255,827	$ 262,003	$ 266,286	285,222	$ 278,969	$ 277,202	$ 275,770	1,040,155	1,117,164	$ 1,074,729
Rents from significant lessee
Concentration Risk [Line Items]
Total revenues									1,040,155	1,117,164
Real Estate Investment Property At Cost \| Rents from significant lessee
Concentration Risk [Line Items]
Gross Book Value of Real Estate Assets	8,420,623				8,428,644				$ 8,420,623	$ 8,428,644
Concentration of credit risk (as a percent)									100.00%	100.00%
Real Estate Investment Property At Cost \| Rents from significant lessee \| Senior Living Communities
Concentration Risk [Line Items]
Gross Book Value of Real Estate Assets					1,920,070					$ 1,920,070
Revenue
Concentration Risk [Line Items]
Concentration of credit risk (as a percent)									100.00%	100.00%
Revenue \| Senior Living Communities
Concentration Risk [Line Items]
Total revenues									$ 433,597	$ 416,523
Five Star \| Rents from significant lessee
Concentration Risk [Line Items]
Total revenues									137,898	212,622
Five Star \| Real Estate Investment Property At Cost \| Rents from significant lessee
Concentration Risk [Line Items]
Gross Book Value of Real Estate Assets	2,286,951				2,253,853				$ 2,286,951	$ 2,253,853
Concentration of credit risk (as a percent)									27.20%	26.70%
Five Star \| Real Estate Investment Property At Cost \| Rents from significant lessee \| Discontinued Operations, Held-for-sale
Concentration Risk [Line Items]
Gross Book Value of Real Estate Assets	50,951								$ 50,951
Five Star \| Revenue
Concentration Risk [Line Items]
Concentration of credit risk (as a percent)									13.30%	19.00%
All others \| Real Estate Investment Property At Cost \| Rents from significant lessee
Concentration Risk [Line Items]
Gross Book Value of Real Estate Assets	6,133,672				6,174,791				$ 6,133,672	$ 6,174,791
Concentration of credit risk (as a percent)									72.80%	73.30%
All others \| Real Estate Investment Property At Cost \| Rents from significant lessee \| Discontinued Operations, Held-for-sale
Concentration Risk [Line Items]
Gross Book Value of Real Estate Assets	$ 213,416				$ 3,752				$ 213,416	$ 3,752
All others \| Revenue
Concentration Risk [Line Items]
Concentration of credit risk (as a percent)									86.70%	81.00%
Total revenues									$ 902,257	$ 904,542