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SHARE-BASED COMPENSATION - Additional Information (Details) - USD ($) $ / shares in Units, $ in Millions |  | 1 Months Ended | 9 Months Ended
--- | --- | --- | ---
Jan. 01, 2021 | May 31, 2021 | Sep. 30, 2021 | Sep. 30, 2020
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |
Stock-based compensation expense |  |  | $ 2.1 | $ 1.5
2015 Incentive Plan |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |
Number of shares (in shares) |  |  | 775,000 |
Term of award |  |  | 10 years |
2021 LTIP Awards |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |
Term of award |  |  | 3 years |
2021 LTIP Awards | Performance Shares |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |
Performance RSUs eligible to be earned (in shares) | 38,448 |  |  |
Percentage of performance RSUs eligible to be earned over granted shares | 2 |  |  |
Expected volatility |  |  | 20.63% |
Risk-free rate |  |  | 0.17% |
Expected term |  |  | 3 years |
Exercise price (in dollars per share) | $ 70.64 |  |  |
2021 LTIP Awards | Stock Options |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |
Expected volatility |  |  | 21.08% |
Risk-free rate |  |  | 0.65% |
Expected term |  |  | 6 years 3 months |
Exercise price (in dollars per share) |  |  | $ 70.64 |
2021 LTIP Awards | Tranche One | Stock Options |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |
Restricted shares vesting percentage | 25.00% |  |  |
2021 LTIP Awards | Tranche Two | Stock Options |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |
Restricted shares vesting percentage | 25.00% |  |  |
2021 LTIP Awards | Tranche Three | Stock Options |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |
Restricted shares vesting percentage | 25.00% |  |  |
2021 LTIP Awards | Tranche Four | Stock Options |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |
Restricted shares vesting percentage | 25.00% |  |  |
2021 LTIP Awards | Employees |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |
Options granted (in shares) | 43,629 |  |  |
Fair value of stock options (in dollars per share) | $ 7.383 |  |  |
2021 LTIP Awards | Employees | Performance Shares |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |
Awards granted (in shares) | 19,224 |  |  |
2021 LTIP Awards | Employees | Restricted Stock Units (RSUs) |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |
Awards granted (in shares) | 6,410 |  |  |
2021 LTIP Awards | Trustee | Restricted Stock Units (RSUs) |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award [Line Items] |  |  |  |
Awards granted (in shares) |  | 6,948 |  |
Vesting period |  | 1 year |  |

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- Definition The estimated measure of the percentage by which a share price is expected to fluctuate during a period. Volatility also may be defined as a probability-weighted measure of the dispersion of returns about the mean. The volatility of a share price is the standard deviation of the continuously compounded rates of return on the share over a specified period. That is the same as the standard deviation of the differences in the natural logarithms of the stock prices plus dividends, if any, over the period. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (f)(2)(ii) -URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901 + Details
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