STOCK-BASED COMPENSATION - Vesting Conditions (Details)	3 Months Ended
Mar. 31, 2021 shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted, Number of share of restricted stock (shares)	152,171
Restricted stock units, type 1
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted, Number of share of restricted stock (shares)	66,220
Target, Regional adjusted EBITDA, percentage	70.00%
Target, Group adjusted EBITDA, percentage	30.00%
Restricted stock units, type 1 \| Performance Conditions, 2020
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Target, Group adjusted EBITDA, percentage	75.00%
Target, Corporate costs , percentage	25.00%
Restricted stock units, type 1 \| Performance Conditions, 2021
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Target, Group adjusted EBITDA, percentage	100.00%
Restricted stock units, type 1 \| First Anniversary
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted, Number of share of restricted stock (shares)	53,075
Vesting rights, percentage	33.00%
Restricted stock units, type 1 \| Second Anniversary
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting rights, percentage	33.00%
Restricted stock units, type 1 \| Third Anniversary
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting rights, percentage	34.00%
Restricted stock units, type 2
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted, Number of share of restricted stock (shares)	60,451
Restricted stock units, type 2 \| First Anniversary
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting rights, percentage	66.60%
Restricted stock units, type 2 \| Second Anniversary
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted, Number of share of restricted stock (shares)	73,596
Vesting rights, percentage	16.70%
Restricted stock units, type 2 \| Third Anniversary
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting rights, percentage	16.70%
Restricted stock units, time
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted, Number of share of restricted stock (shares)	25,500

Share-based Compensation Arrangement by Share-based Payment Award, Target, Corporate Costs

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- Definition

Share-based Compensation Arrangement by Share-based Payment Award, Target, Group Adjusted EBITDA

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- Definition

Share-based Compensation Arrangement by Share-based Payment Award, Target, Regional Adjusted EBITDA

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- Definition

The number of grants made during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

+ 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 (c)(2)(iii)(1)
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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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- Definition

Percentage of vesting of award under share-based payment arrangement.

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)(1)
-URI http://asc.fasb.org/extlink&oid=116856206&loc=d3e5070-113901

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