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

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

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Represents the percentage of option awards which vest annually on the anniversary date of the award.

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No definition available.

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

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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.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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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.

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Unrecognized cost of unvested share-based awards, other than options, awarded to employees as compensation.

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Unrecognized cost of unvested options awarded to employees as compensation.

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Period which an employee's right to exercise an award is no longer contingent on satisfaction of either a service condition, market condition or a performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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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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- Definition

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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No definition available.

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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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Number of additional shares authorized for issuance under an established share-based compensation plan.

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No definition available.

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The maximum number of shares (or other type of equity) originally approved (usually by shareholders and board of directors), net of any subsequent amendments and adjustments, for awards under the equity-based compensation plan. As stock or unit options and equity instruments other than options are awarded to participants, the shares or units remain authorized and become reserved for issuance under outstanding awards (not necessarily vested).

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The difference between the maximum number of shares (or other type of equity) authorized for issuance under the plan (including the effects of amendments and adjustments), and the sum of: 1) the number of shares (or other type of equity) already issued upon exercise of options or other equity-based awards under the plan; and 2) shares (or other type of equity) reserved for issuance on granting of outstanding awards, net of cancellations and forfeitures, if applicable.

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Gross number of share options (or share units) granted during the period.

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No definition available.

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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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- Definition

Weighted average per share amount at which grantees can acquire shares of common stock by exercise of options.

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No definition available.

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Period from grant date that an equity-based award expires, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Value of stock issued as a result of the exercise of stock options.

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STOCKHOLDERS' EQUITY - Options (Details) $ / shares in Units, shares in Millions, $ in Millions		3 Months Ended		6 Months Ended
	Apr. 06, 2017 shares	Jun. 30, 2018 USD ($) shares	Jun. 30, 2017 USD ($)	Jun. 30, 2018 USD ($) $ / shares shares	Jun. 30, 2017 USD ($) $ / shares shares	Dec. 31, 2017 shares	Sep. 09, 2016 shares
General and administrative
Stock-based compensation
Compensation expense recorded \| $		$ 4.2	$ 12.9	$ 7.8	$ 21.3
Stock options \| Employee
Stock-based compensation
Percentage of awards vesting on the annual anniversary date of the grant		33.33		33.33
Vesting period				3 years
Expiration term				10 years
2016 Incentive Plan \| Common Stock
Stock-based compensation
Aggregate number of shares available \| shares	19.0						10.0
Maximum number of shares that remained reserved for issuance under the Plan \| shares		4.9		4.9		7.7
Increase in shares available for issuance \| shares	9.0
Number of calculation days for which shares will be available for issuance.	20 days
2016 Incentive Plan \| Stock options
Stock-based compensation
Weighted average remaining vesting period				1 year	1 year 4 months 24 days
Exercise of stock options \| $				$ 0.3
Restricted stock
Unrecognized compensation expense stock option \| $		$ 9.9	23.1	$ 9.9	$ 23.1
2016 Incentive Plan \| Stock options \| Employee
Number of Shares
Granted (in shares) \| shares				1.2	1.8
Weighted Average Exercise Price Per Share
Granted (in dollars per share)				$ 5.65	$ 7.72
2016 Incentive Plan \| Stock options \| Employee \| Minimum
Weighted Average Exercise Price Per Share
Granted (in dollars per share)					6.55
2016 Incentive Plan \| Stock options \| Employee \| Maximum
Weighted Average Exercise Price Per Share
Granted (in dollars per share)					$ 7.75
2016 Incentive Plan \| Restricted Stock
Stock-based compensation
Weighted average remaining vesting period				1 year 6 months	9 months 18 days
Weighted average grant date price (in dollars per share)				$ 5.53	$ 7.07
Unrecognized compensation expense other than options \| $		$ 11.0	$ 13.9	$ 11.0	$ 13.9
2016 Incentive Plan \| Restricted Stock \| Minimum
Stock-based compensation
Grant date price (in dollars per share)				$ 4.00	$ 6.08
2016 Incentive Plan \| Restricted Stock \| Maximum
Stock-based compensation
Grant date price (in dollars per share)				$ 5.65	$ 7.75
2016 Incentive Plan \| Restricted Stock \| Employees and non-employee directors
Number of Shares
Granted (in shares) \| shares				2.2	2.0
2016 Incentive Plan \| Restricted Stock \| Employee
Stock-based compensation
Percentage of awards other than options vesting on the annual anniversary date of the grant				33.33%
Vesting period				3 years
2016 Incentive Plan \| Restricted Stock \| Non-employee director
Stock-based compensation
Vesting period				6 months