STOCKHOLDERS' EQUITY AND SHARE-BASED COMPENSATION PLANS - Stock Option Activity (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Outstanding Stock Options
Balance (in shares)	575,924	528,647
Granted (in shares)	276,830	262,319
Exercised (in shares)	(220)	(104,445)
Forfeited (in shares)	(284,692)	(110,597)
Balance (in shares)	567,842	575,924	528,647
Exercisable at end of period (in shares)	271,356
Weighted-Average Exercise Price
Balance (usd per share)	$ 109.01	$ 123.51
Granted (usd per share)	26.12	68.79
Exercised (usd per share)	25.50	31.99
Forfeited (usd per share)	93.81	155.64
Balance (usd per share)	76.25	$ 109.01	$ 123.51
Exercisable at end of period (usd per share)	$ 109.26
Outstanding Stock Options, Other Disclosures
Weighted-average remaining contractual term, outstanding	7 years 9 months 26 days	8 years 1 month 2 days	7 years 4 months 6 days
Weighted-average remaining contractual term, exercisable	6 years 7 months 28 days
Aggregate intrinsic value, outstanding	$ 12	$ 87	$ 7,223
Aggregate intrinsic value, exercisable	$ 5

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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.

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Weighted average price of options that were either forfeited or expired.

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

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

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Number of options outstanding, including both vested and non-vested options.

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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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Weighted average price at which grantees can acquire the shares reserved for issuance under the stock option plan.

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Amount by which current fair value of underlying stock exceeds exercise price of fully vested and expected to vest exercisable or convertible options. Includes, but is not limited to, unvested options for which requisite service period has not been rendered but that are expected to vest based on achievement of performance condition, if forfeitures are recognized when they occur.

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Weighted average price at which option holders acquired shares when converting their stock options into shares.

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

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The number of shares reserved for issuance pertaining to the outstanding exercisable stock options as of the balance sheet date in the customized range of exercise prices for which the market and performance vesting condition has been satisfied.

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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.

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Number of non-vested options forfeited.

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Weighted average remaining contractual term for option awards outstanding, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Number of share options (or share units) exercised during the current period.

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