STOCKHOLDERS' EQUITY - Restricted Stock (Details) - 2016 Incentive Plan - Restricted Stock - USD ($) $ / shares in Units, shares in Millions, $ in Millions	6 Months Ended
Jun. 30, 2019	Jun. 30, 2018
Stock-based compensation
Weighted average grant date price (in dollars per share)	$ 1.29	$ 5.53
Unrecognized compensation expense other than options	$ 6.5	$ 11.0
Weighted average remaining vesting period	1 year 7 months 6 days	1 year 6 months
Minimum
Stock-based compensation
Grant date price (in dollars per share)	$ 1.29	$ 4.00
Maximum
Stock-based compensation
Grant date price (in dollars per share)	$ 1.40	$ 5.65
Employee
Stock-based compensation
Vesting period	3 years
Percentage of awards other than options vesting on the annual anniversary date of the grant	33.33%
Employees and non-employee directors
Stock-based compensation
Number of shares granted	4.2	2.2
Non-employee director
Stock-based compensation
Vesting period	6 months

Represents the market price of equity instruments, other than options, on date of grant.

No definition available.

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- Definition

Represents the weighted average market price of equity instruments, other than options, on date of grant.

+ References

No definition available.

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- Definition

Represents the percentage of awards other than options which vest annually on the anniversary date of the award.

+ References

No definition available.

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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.

+ References

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (i)
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- Definition

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

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- Definition

Period over which grantee's right to exercise award under share-based payment arrangement is no longer contingent on satisfaction of service or performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days. Includes, but is not limited to, combination of market, performance or service condition.

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-Topic 718
-SubTopic 10
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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

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

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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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