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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-Publisher FASB
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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=6879938&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://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 4
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-URI http://asc.fasb.org/extlink&oid=109196051&loc=SL49130543-203045

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-Publisher FASB
-Name Accounting Standards Codification
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-URI http://asc.fasb.org/extlink&oid=109196051&loc=SL49130539-203045

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
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-URI http://asc.fasb.org/extlink&oid=109196051&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, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Concentration Risk [Line Items]
Carrying Value of Investment	$ 7,876,300				$ 7,824,763				$ 7,876,300	$ 7,824,763
Total revenues	285,222	$ 278,969	$ 277,202	$ 275,770	278,543	$ 266,673	$ 264,992	$ 264,521	1,117,164	1,074,729	$ 1,058,022
Real Estate Investment Property At Cost \| Rents from significant lessee
Concentration Risk [Line Items]
Carrying Value of Investment	8,428,644				8,474,950				$ 8,428,644	$ 8,474,950
Concentration of credit risk (as a percent)									100.00%	100.00%
Sales Revenue, Services, Net \| Rents from significant lessee
Concentration Risk [Line Items]
Concentration of credit risk (as a percent)									100.00%	100.00%
Total revenues									$ 1,117,164	$ 1,074,819
Five Star \| Real Estate Investment Property At Cost \| Rents from significant lessee
Concentration Risk [Line Items]
Carrying Value of Investment	2,253,853				2,330,630				$ 2,253,853	$ 2,330,630
Concentration of credit risk (as a percent)									26.70%	27.50%
Five Star \| Sales Revenue, Services, Net \| Rents from significant lessee
Concentration Risk [Line Items]
Concentration of credit risk (as a percent)									19.00%	19.60%
Total revenues									$ 212,622	$ 210,539
All others \| Real Estate Investment Property At Cost \| Rents from significant lessee
Concentration Risk [Line Items]
Carrying Value of Investment	$ 6,174,791				$ 6,144,320				$ 6,174,791	$ 6,144,320
Concentration of credit risk (as a percent)									73.30%	72.50%
All others \| Sales Revenue, Services, Net \| Rents from significant lessee
Concentration Risk [Line Items]
Concentration of credit risk (as a percent)									81.00%	80.40%
Total revenues									$ 904,542	$ 864,280