v3.26.1
Per Common Share Amounts - Schedule of Earnings Per Share (Details) - USD ($)
$ / shares in Units, shares in Thousands, $ in Thousands
 3 Months Ended 9 Months Ended
Jun. 30, 2026
Jun. 30, 2025
Jun. 30, 2026
Jun. 30, 2025
Numerators:        
Net income attributable to The RMR Group Inc. $ 3,197 $ 4,186 $ 16,394 $ 14,182
Less: income attributable to unvested participating securities (136) (101) (420) (310)
Net income used in calculating basic EPS 3,061 4,085 15,974 13,872
Add back: income attributable to unvested participating securities 0 0 0 310
Add back: net income attributable to noncontrolling interest in The RMR Group LLC 0 0 0 17,259
Add back: income tax expense 0 0 0 5,607
Less: income tax expense assuming redemption of noncontrolling interest’s Class A units for Class A common shares 0 0 0 (11,037)
Net income used in calculating diluted EPS $ 3,061 $ 4,085 $ 15,974 $ 26,011
Denominators:        
Common shares outstanding (in shares) 17,092 16,870 17,092 16,870
Less: unvested participating securities and incremental impact of weighted average (in shares) (301) (210) (330) (240)
Weighted average common shares outstanding - basic (in shares) 16,791 16,660 16,762 16,630
Add: assumed redemption of noncontrolling interest’s Class A Units for Class A common shares (in shares) 0 0 0 15,000
Add: Incremental unvested shares (in shares) 0 0 0 3
Weighted average common shares outstanding - diluted (in shares) 16,791 16,660 16,762 31,633
Net income attributable to The RMR Group Inc. per common share - basic (in usd per share) $ 0.18 $ 0.25 $ 0.95 $ 0.83
Net income attributable to The RMR Group Inc. per common share - diluted (in usd per share) $ 0.18 $ 0.25 $ 0.95 $ 0.82
Income tax expense, estimate tax rate (percent)       29.80%