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Shareholders' Equity - Narrative (Details) - USD ($) $ / shares in Units, $ in Thousands |  | 1 Months Ended | 12 Months Ended |  |
--- | --- | --- | --- | --- | ---
Feb. 22, 2018 | Jan. 31, 2018 | May 31, 2017 | May 31, 2016 | Dec. 31, 2015 | Sep. 30, 2015 | May 31, 2015 | Dec. 31, 2017 | Dec. 31, 2016 | Dec. 31, 2015 | Jan. 19, 2018 | Dec. 31, 2014
Scheduled to vest unvested shares |  |  |  |  |  |  |  |  |  |  |  |
Share-based compensation expense |  |  |  |  |  |  |  | $ 2,155 | $ 2,195 | $ 1,373 |  |
Distribution to common shareholders (in dollars per share) |  |  |  |  |  |  |  | $ 1.56 | $ 1.56 | $ 1.56 |  |
Distribution to common shareholders |  |  |  |  |  |  |  | $ 370,608 | $ 370,489 | $ 356,390 |  |
Dividends paid in kind per share |  |  |  |  | $ 0.1320 |  |  |  |  |  |  |
Common stock dividends, ordinary income distribution percentage |  |  |  |  |  |  |  | 88.44% | 58.77% | 51.48% |  |
Common stock dividends, capital distribution percentage |  |  |  |  |  |  |  | 0.00% | 40.67% | 47.80% |  |
Common stock dividends, qualified distribution percentage |  |  |  |  |  |  |  | 0.71% | 0.56% | 0.72% |  |
Common stock dividends, capital gain distribution percentage |  |  |  |  |  |  |  | 10.85% | 0.00% | 0.00% |  |
RMR LLC |  |  |  |  |  |  |  |  |  |  |  |
Scheduled to vest unvested shares |  |  |  |  |  |  |  |  |  |  |  |
Shares issued in connection with acquisition |  |  |  |  |  |  |  |  |  | 81,557 |  |
Distribution to common shareholders |  |  |  |  | $ 2,635 |  |  |  |  |  |  |
Distribution ratio, RMR Inc shares per common shares |  |  |  |  | 0.0111 |  |  |  |  |  |  |
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 |  |  |  |  |  |  |  | 17,170 | 19,230 |  |  |
Share Award Plans |  |  |  |  |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Remaining common shares available for issuance |  |  |  |  |  |  |  | 2,481,686 |  |  |  |
Number of unvested shares |  |  |  |  | 158,874 |  |  | 148,010 | 153,410 | 158,874 |  | 153,478
Scheduled to vest unvested shares |  |  |  |  |  |  |  |  |  |  |  |
2018 |  |  |  |  |  |  |  | 57,250 |  |  |  |
2019 |  |  |  |  |  |  |  | 44,230 |  |  |  |
2020 |  |  |  |  |  |  |  | 30,410 |  |  |  |
2021 |  |  |  |  |  |  |  | 16,120 |  |  |  |
Estimated future compensation for the unvested shares |  |  |  |  |  |  |  | $ 2,834 |  |  |  |
Closing share price (in dollars per share) |  |  |  |  |  |  |  | $ 19.15 |  |  |  |
Weighted average period over which the compensation expense will be recorded |  |  |  |  |  |  |  | 1 year 8 months 12 days |  |  |  |
Share Award Plans | Trustees |  |  |  |  |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Common shares awarded |  |  | 3,000 | 2,500 |  | 2,500 | 2,500 |  |  |  |  |
Aggregate market value of shares awarded |  |  |  |  |  | $ 41 |  |  |  |  |  |
Share Award Plans | RMR LLC | Officers and Employees |  |  |  |  |  |  |  |  |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |  |  |  |  |  |  |  |  |
Aggregate market value of shares awarded |  |  | $ 319 | $ 228 |  |  | $ 252 |  |  |  |  |
Market value of shares awarded to each Trustee |  |  | $ 64 | $ 46 |  |  | $ 50 |  |  |  |  |
Award vesting period |  |  |  |  |  |  |  | 5 years |  |  |  |
Subsequent Event |  |  |  |  |  |  |  |  |  |  |  |
Scheduled to vest unvested shares |  |  |  |  |  |  |  |  |  |  |  |
Repurchase of common shares (in shares) |  | 4,628 |  |  |  |  |  |  |  |  |  |
Share price (in dollars per share) |  | $ 19.15 |  |  |  |  |  |  |  |  |  |
Distribution to common shareholders (in dollars per share) | $ 0.39 |  |  |  |  |  |  |  |  |  |  |
Distribution declared to common shareholders (in dollars per share) |  |  |  |  |  |  |  |  |  |  | $ 0.39 |
Distribution declared to common shareholders |  |  |  |  |  |  |  |  |  |  | $ 92,676 |
Dividends | $ 92,642 |  |  |  |  |  |  |  |  |  |  |

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