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Shareholders' Equity - Narrative (Details) - USD ($) $ / shares in Units, $ in Thousands |  |  | 1 Months Ended | 12 Months Ended |
--- | --- | --- | --- | --- | ---
Jan. 14, 2021 | Jan. 01, 2020 | Mar. 31, 2018 | Dec. 31, 2020 | Dec. 31, 2019 | Dec. 31, 2018 | Dec. 31, 2017
Scheduled to vest unvested shares |  |  |  |  |  |  |
Share-based compensation expense |  |  |  | $ 1,568 | $ 1,388 | $ 2,224 |
Distributions to shareholders |  |  |  | $ 42,825 | $ 199,719 | $ 370,746 |
Five Star |  |  |  |  |  |  |
Scheduled to vest unvested shares |  |  |  |  |  |  |
Aggregate shares issued (shares) |  |  |  |  | 16,118,849 |  |
Subsequent Event |  |  |  |  |  |  |
Scheduled to vest unvested shares |  |  |  |  |  |  |
Common distributions declared (in dollars per share) | $ 0.01 |  |  |  |  |  |
Distributions to shareholders | $ 2,383 |  |  |  |  |  |
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) |  |  |  | 47,375 | 31,747 | 22,999 |
Five Star |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award |  |  |  |  |  |  |
Market value of shares awarded to each Trustee |  | $ 59,801 |  |  |  |  |
Share Award Plans |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award |  |  |  |  |  |  |
Remaining common shares available for issuance (in shares) |  |  |  | 1,843,617 |  |  |
Number of unvested shares (in shares) |  |  |  | 434,550 | 227,340 | 161,990 | 148,010
Scheduled to vest unvested shares |  |  |  |  |  |  |
2021 (in shares) |  |  |  | 158,330 |  |  |
2022 (in shares) |  |  |  | 111,920 |  |  |
2023 (in shares) |  |  |  | 97,900 |  |  |
2024 (in shares) |  |  |  | 66,400 |  |  |
Estimated future compensation for the unvested shares |  |  |  | $ 2,205 |  |  |
Weighted average period over which the compensation expense will be recorded |  |  |  | 1 year 10 months 24 days |  |  |
Officers and Employees | Share Award Plans | RMR LLC |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award |  |  |  |  |  |  |
Common shares awarded (in shares) |  |  |  | 360,000 | 187,500 | 105,800 |
Aggregate market value of shares awarded |  |  |  | $ 1,357 | $ 1,633 | $ 2,022 |
Award vesting period |  |  |  | 5 years |  |  |
Trustees | Share Award Plans |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award |  |  |  |  |  |  |
Common shares awarded (in shares) |  |  | 3,000 |  |  |  |
Aggregate market value of shares awarded |  |  | $ 47 |  |  |  |
Trustees | Share Award Plans | RMR LLC |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award |  |  |  |  |  |  |
Common shares awarded (in shares) |  |  |  | 10,000 | 3,000 | 3,000 |
Aggregate market value of shares awarded |  |  |  | $ 176 | $ 119 | $ 248 |
Market value of shares awarded to each Trustee |  |  |  | $ 29 | $ 24 | $ 50 |

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