EQUITY-BASED COMPENSATION - Stock options (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended
Mar. 31, 2019	Mar. 31, 2018
Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of exercisable shares (in shares)	235,000
Weighted average exercise price, exercisable (in dollars per share)	$ 9.75
Weighted average remaining contractual terms, exercisable	1 year 10 months 24 days
Aggregate intrinsic value, outstanding	$ 0.4
Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock options term	5 years
Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock options term	10 years
Chief Financial Officer
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share based compensation expense		$ 1.0

Share-based Compensation Arrangement by Share-based Payment Award, Options, Term

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- Definition

Represents the expense recognized during the period arising from equity-based compensation arrangements (for example, shares of stock, unit, stock options or other equity instruments) with employees, directors and certain consultants qualifying for treatment as employees.

+ References

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (b)
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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.

+ References

No definition available.

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- Definition

The number of shares into which fully or partially vested stock options outstanding as of the balance sheet date can be currently converted under the option 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
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- Definition

The weighted-average price as of the balance sheet date at which grantees can acquire the shares reserved for issuance on vested portions of options outstanding and currently exercisable under the stock option plan.

+ References

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- Definition

Amount by which the current fair value of the underlying stock exceeds the exercise price of options outstanding.

+ References

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-Publisher FASB
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- Definition

Weighted average remaining contractual term for vested portions of options outstanding and currently exercisable or convertible, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

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