Represent the amounts due from related person, owed to us from SIR related to working capital activity for MOBs.

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Represents the amount of premium payable for combined directors' and officers' liability insurance policy.

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Represents the percentage of economic interest held in RMR Inc.

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This element represents the amount of annual premiums including taxes and fees for property insurance pursuant to an insurance program arranged by the equity method investee.

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Represents the number of shares held as a percentage of the total shares outstanding at the end of the period.

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Represents the minimum percentage of common stock held in the investee above which the entity would have the option to cancel all its rights.

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Amount of non cash loss, which represents difference between our carrying value and the fair value of the RMR Inc. shares on the distribution date

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Number of shares distributed to the shareholders.

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Related Person Transactions - Narrative (Details) $ / shares in Units, $ in Thousands						1 Months Ended					3 Months Ended	12 Months Ended
	Nov. 09, 2017 USD ($) property	Nov. 10, 2016 $ / shares shares	Dec. 14, 2015 shares	Jun. 05, 2015 USD ($) shares	Jan. 29, 2015 USD ($) property	Mar. 31, 2017 building	Sep. 30, 2015 USD ($)	May 31, 2015 USD ($)	Apr. 30, 2015 USD ($) property	Jan. 31, 2015 USD ($) living_unit	Dec. 31, 2015 USD ($) community	Dec. 31, 2017 USD ($) community building property party lease_agreement trustee agreement shares	Dec. 31, 2016 USD ($) community property shares	Dec. 31, 2015 USD ($) community property shares	Dec. 31, 2001
Related Party Transaction [Line Items]
Loss on distribution to common shareholders of The RMR Group Inc. common stock												$ 0	$ 0	$ 38,437
Number Of Independent Trustees \| trustee												1
Fair value adjustment, liabilities												$ 1,906
Equity in earnings of an investee												608	137	20
Other comprehensive income (loss) attributable to equity method investee, net of tax												$ (462)	(152)	20
Number of buildings included in joint venture agreement \| building						2
The RMR Group Inc
Related Party Transaction [Line Items]
Investment in common shares \| shares												2,637,408
Economic interest percent												51.90%
Voting power percent												91.40%
Number Of Unrelated Parties \| party												4
Related party transaction, rate												3.00%
RMR Inc. \| Class A common shares
Related Party Transaction [Line Items]
Loss on distribution to common shareholders of The RMR Group Inc. common stock											$ 38,437
RMR Inc. \| Up C Transaction
Related Party Transaction [Line Items]
Cash purchase price				$ 13,967
RMR Inc. \| Up C Transaction \| Common Shares
Related Party Transaction [Line Items]
Shares issued in connection with acquisition \| shares				2,345,000
RMR LLC
Related Party Transaction [Line Items]
Rental revenue from related party												$ 331	$ 242	$ 204
RMR Inc. \| Class A common shares
Related Party Transaction [Line Items]
Shares distributed to stockholders \| shares			2,635,379
RMR Inc. \| Up C Transaction \| Managing Trustees Barry And Adam Portnoy
Related Party Transaction [Line Items]
Number of shares under lock up and registration agreement \| shares				2,345,000
Period over which shares remain under lock up and registration agreement				10 years
RMR Inc. \| RMR Inc. \| Up C Transaction \| Class B2 common shares
Related Party Transaction [Line Items]
Shares issued in connection with acquisition \| shares				5,272,787
Senior Living Communities \| Acquisitions
Related Party Transaction [Line Items]
Number of properties acquired or agreed to be acquired \| property													10	39
Purchase price excluding closing costs and working capital adjustments							$ 18,250	$ 9,750
MOBs
Related Party Transaction [Line Items]
Standalone Insurance Policy Coverage Period												1 year
Number of buildings included in joint venture agreement \| building												2
MOBs \| Acquisitions
Related Party Transaction [Line Items]
Number of properties acquired or agreed to be acquired										23		6	3	23
Purchase price excluding closing costs and working capital adjustments										$ 539,000
MOBs \| SIR \| Acquisitions
Related Party Transaction [Line Items]
Debt disposed of from properties sold					$ 29,995
Amount from SIR related to working capital activity									$ 1,316
Five Star
Related Party Transaction [Line Items]
Percentage of total shares outstanding												8.40%			100.00%
Investment in common shares \| shares												4,235,000
Maximum percentage of any class of equity shares that can be acquired without approval												9.80%
Minimum percentage of ownership of lessee's voting stock above which the entity has the option to cancel all its rights												9.80%
Number of real estate properties leased \| community											177	185	185	177
Property subject to or available for operating lease, number of leases \| lease_agreement												5
Related party transactions, shares authorized to purchase \| shares		18,000,000
Related party transaction, percent of shares issued and outstanding		38.00%
Related party transaction, shares purchased \| shares		17,999,999
Share price (in dollars per share) \| $ / shares		$ 3.00
Five Star \| RMR LLC
Related Party Transaction [Line Items]
Percentage of total shares outstanding												36.40%
Investment in common shares \| shares												18,382,121
Five Star \| Senior Living Communities
Related Party Transaction [Line Items]
Number of communities managed \| community												70	68	60
Five Star \| Senior Living Communities \| Acquisitions
Related Party Transaction [Line Items]
Number of communities managed \| community												5
Number of properties acquired or agreed to be acquired \| property	6
Purchase price excluding closing costs and working capital adjustments	$ 104,000
RMR LLC
Related Party Transaction [Line Items]
Number of management agreements with related party \| agreement												2
Shares issued in connection with acquisition \| shares														81,557
Premium payable for combined directors' and officers' liability insurance policy											$ 472	$ 255	$ 142	$ 472
RMR LLC \| Restricted shares
Related Party Transaction [Line Items]
Number of shares granted under the award plan \| shares												88,100	79,650	84,000
Aggregate value of awards granted during the period												$ 1,743	$ 1,724	$ 1,321
SIR \| MOBs \| Acquisitions
Related Party Transaction [Line Items]
Number of properties acquired or agreed to be acquired \| property					23				23
Purchase price excluding closing costs and working capital adjustments					$ 532,000
Fair value adjustment, liabilities					$ 7,677
AIC
Related Party Transaction [Line Items]
Total premiums including taxes and fees												2,433	3,607	$ 2,785
Equity method investments, carrying value												$ 8,185	$ 7,116
Year one \| RMR LLC \| RMR Inc.
Related Party Transaction [Line Items]
Award vesting rights, percentage												20.00%
Year two \| RMR LLC \| RMR Inc.
Related Party Transaction [Line Items]
Award vesting rights, percentage												20.00%
Year three \| RMR LLC \| RMR Inc.
Related Party Transaction [Line Items]
Award vesting rights, percentage												20.00%
Year four \| RMR LLC \| RMR Inc.
Related Party Transaction [Line Items]
Award vesting rights, percentage												20.00%
Year five \| RMR LLC \| RMR Inc.
Related Party Transaction [Line Items]
Award vesting rights, percentage												20.00%