STOCK-BASED COMPENSATION Restricted stock (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average service period	0 days	0 days
Restricted stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average service period	0 days	0 days
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Roll Forward]
Non-vested restricted stock (units) at January 1, weighted average grant date fair value	$ 0.00	$ 1.60	$ 3.00
Granted, weighted average grant date fair value	0.00	0.00	2.17
Vested, weighted average grant date fair value	0.00	2.45	2.90
Forfeitures, Weighted Average Grant Date Fair Value	0.00	0.85	3.14
Non-vested restricted stock (units) at December 31, weighted average grant date fair value	$ 0.00	$ 0.00	$ 1.60
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Unvested restricted stock (units) at January 1, number of shares of restricted stock (unit)	0	680,000	803,999
Granted, number of share of restricted stock (units)	0	0	1,270,500
Vested, number of share of restricted stock (units)	0	(330,000)	(1,204,798)
Forfeited, number of share of restricted stock (units)	0	(350,000)	(189,701)
Unvested restricted stock (units) at December 31, number of shares of restricted stock (unit)	0	0	680,000
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Total Fair Value	$ 0	$ 553	$ 2,675
Restricted stock units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average service period	1 year 6 months 18 days	1 year 6 months 18 days
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Roll Forward]
Non-vested restricted stock (units) at January 1, weighted average grant date fair value	$ 2.79	$ 0.00	$ 3.57
Granted, weighted average grant date fair value	1.09	2.56	2.47
Vested, weighted average grant date fair value	1.47	2.12	2.70
Forfeitures, Weighted Average Grant Date Fair Value	2.79	2.79	3.21
Non-vested restricted stock (units) at December 31, weighted average grant date fair value	$ 1.16	$ 2.79	$ 0.00
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Unvested restricted stock (units) at January 1, number of shares of restricted stock (unit)	480,000	0	119,940
Granted, number of share of restricted stock (units)	1,404,128	763,477	372,739
Vested, number of share of restricted stock (units)	(462,855)	(263,477)	(450,179)
Forfeited, number of share of restricted stock (units)	(332,340)	(20,000)	(42,500)
Unvested restricted stock (units) at December 31, number of shares of restricted stock (unit)	1,088,933	480,000	0
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Total Fair Value	$ 595	$ 558	$ 1,022

Weighted average period over which unrecognized compensation is expected to be recognized for equity-based compensation plans, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (i)
-URI http://asc.fasb.org/extlink&oid=96867065&loc=d3e5070-113901

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The number of equity-based payment instruments, excluding stock (or unit) options, that were forfeited during the reporting period.

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-Publisher FASB
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Weighted average fair value as of the grant date of equity-based award plans other than stock (unit) option plans that were not exercised or put into effect as a result of the occurrence of a terminating event.

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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).

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The weighted average fair value at grant date for nonvested equity-based awards issued 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).

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The number of non-vested equity-based payment instruments, excluding stock (or unit) options, that validly exist and are outstanding as of the balance sheet date.

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-Publisher FASB
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The weighted average fair value of nonvested awards on equity-based plans excluding option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, revenue or profit achievement stock award plan) for which the employer is contingently obligated to issue equity instruments or transfer assets to an employee who has not yet satisfied service or performance criteria necessary to gain title to proceeds from the sale of the award or underlying shares or units.

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The number of equity-based payment instruments, excluding stock (or unit) options, that vested during the reporting period.

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Fair value of share-based awards for which the grantee gained the right by satisfying service and performance requirements, to receive or retain shares or units, other instruments, or cash.

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The weighted average fair value as of grant date pertaining to an equity-based award plan other than a stock (or unit) option plan for which the grantee gained the right during the reporting period, by satisfying service and performance requirements, to receive or retain shares or units, other instruments, or cash in accordance with the terms of the arrangement.

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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.

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