The aggregate market value of shares newly issued during the reporting period under the plan.

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The number of unvested shares, that will vest in four years.

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The number of unvested shares, that will vest in next fiscal year.

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The number of unvested shares, that will vest in three years.

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The number of unvested shares, that will vest in two years.

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Represents the market value of shares, newly issued during the reporting period under the plan, to each individual.

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Amount of expense for award under share-based payment arrangement. Excludes amount capitalized.

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Aggregate dividends declared during the period for each share of common stock outstanding.

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Amount of cost not yet recognized for nonvested award under share-based payment arrangement.

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Weighted-average period over which cost not yet recognized is expected to be recognized for award under share-based payment arrangement, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

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Amount of cash outflow in the form of ordinary dividends to common shareholders of the parent entity.

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Period over which grantee's right to exercise award under share-based payment arrangement is no longer contingent on satisfaction of service or performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days. Includes, but is not limited to, combination of market, performance or service condition.

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The number of non-vested equity-based payment instruments, excluding stock (or unit) options, that validly exist and are outstanding as of the balance sheet date.

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The difference between the maximum number of shares (or other type of equity) authorized for issuance under the plan (including the effects of amendments and adjustments), and the sum of: 1) the number of shares (or other type of equity) already issued upon exercise of options or other equity-based awards under the plan; and 2) shares (or other type of equity) reserved for issuance on granting of outstanding awards, net of cancellations and forfeitures, if applicable.

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Number of shares issued under share-based payment arrangement.

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Number of shares purchased for issuance under share-based payment arrangement.

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Shareholders' Equity - Narrative (Details) - USD ($) $ / shares in Units, $ in Thousands		1 Months Ended	3 Months Ended								12 Months Ended
	Jan. 16, 2020	Mar. 31, 2018	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	Dec. 31, 2016
Scheduled to vest unvested shares
Share-based compensation expense											$ 1,388	$ 2,224	$ 2,155
Common distributions declared (in dollars per share)			$ 0.15	$ 0.15	$ 0.15	$ 0.39	$ 0.39	$ 0.39	$ 0.39	$ 0.39
Distributions to shareholders											$ (199,719)	$ (370,746)	$ (370,608)
Certain Our Officers And Employees Of RMR LLC
Scheduled to vest unvested shares
Shares purchased from certain of our officers and other employees of RMR LLC (in shares)											31,747	22,999	17,170
Share Award Plans
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Remaining common shares available for issuance (in shares)			2,214,932								2,214,932
Number of unvested shares (in shares)			227,340				161,990				227,340	161,990	148,010	153,410
Scheduled to vest unvested shares
2019 (in shares)											73,080
2020 (in shares)											63,840
2021 (in shares)											53,520
2022 (in shares)											36,900
Estimated future compensation for the unvested shares			$ 2,423								$ 2,423
Weighted average period over which the compensation expense will be recorded											2 years
Share Award Plans \| Trustees
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common shares awarded (in shares)		3,000
Aggregate market value of shares awarded		$ 47
Share Award Plans \| RMR LLC \| Officers and Employees
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common shares awarded (in shares)											187,500	105,800	88,100
Aggregate market value of shares awarded											$ 1,633	$ 2,022	$ 1,743
Award vesting period											5 years
Share Award Plans \| RMR LLC \| Trustees
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common shares awarded (in shares)											3,000	3,000	3,000
Aggregate market value of shares awarded											$ 119	$ 248	$ 319
Market value of shares awarded to each Trustee											$ 24	$ 50	$ 64
Subsequent Event
Scheduled to vest unvested shares
Common distributions declared (in dollars per share)	$ 0.15
Distributions to shareholders	$ (35,684)