EQUITY- BASED COMPENSATION - RSUs (Details) $ / shares in Units, shares in Thousands, $ in Thousands	6 Months Ended
Jun. 30, 2020 USD ($) $ / shares shares
RSUs, Number of shares
Nonvested, Number, Beginning Balance \| shares	951
RSUs granted, number \| shares	2,696
RSUs vested, number \| shares	(491)
RSUs forfeited, number \| shares	(214)
Nonvested, Number, Ending Balance \| shares	2,942
RSUs, Weighted average grant-date fair value
Nonvested, Weighted Average Grant Date Fair Value, Beginning Balance \| $ / shares	$ 2.15
RSUs granted, grant-date fair value \| $ / shares	0.70
RSUs vested, grant-date fair value \| $ / shares	2.36
RSUs forfeited, grant-date fair value \| $ / shares	1.11
Nonvested, Weighted Average Grant Date Fair Value, Ending Balance \| $ / shares	$ 0.87
Fair value of RSUs that vested during the period \| $	$ 362
Unrecognized compensation, RSUs \| $	$ 2,059
Restricted stock units
RSUs, Weighted average grant-date fair value
Unrecognized compensation, period for recognition	1 year 11 months 8 days

Weighted-average period over which cost not yet recognized is expected to be recognized for award under share-based payment arrangement, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

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Amount of cost to be recognized for nonvested award under share-based payment arrangement. Excludes share and unit options.

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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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- Definition

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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A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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Per share or unit weighted-average fair value of nonvested award under share-based payment arrangement. Excludes share and unit options.

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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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