STOCK-BASED COMPENSATION - Stock Option Activity (Details) - $ / shares	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Options, Outstanding at January 1, 2017	3,500
Options, Granted	0	0	0
Options, Exercised	(2,250)
Options, Forfeited/ Expired	(750)
Options, Cancelled	0
Options, Outstanding at December 31, 2017	500	3,500
Options, Vested and expected to vest	500
Options, Exercisable at December 31, 2017	500
Weighted Average Exercise Price, Outstanding at January 1, 2017	$ 15.99
Weighted Average Exercise Price, Granted	0
Weighted Average Exercise Price, Exercised	16.89
Weighted Average Exercise Price, Forfeited/ Expired	17.24
Weighted Average Exercise Price, Cancelled	0
Weighted Average Exercise Price, Outstanding at December 31, 2017	10.04	$ 15.99
Weighted Average Exercise Price, Vested and expected to vest	10.04
Weighted Average Exercise Price, Exercisable at December 31, 2017	$ 10.04

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The number of shares into which fully or partially vested stock options outstanding as of the balance sheet date can be currently converted under the option plan.

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-Publisher FASB
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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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Number of options or other stock instruments for which the right to exercise has lapsed under the terms of the plan agreements.

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The number of shares under options that were cancelled during the reporting period as a result of occurrence of a terminating event specified in contractual agreements pertaining to the stock option plan.

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

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

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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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Number of fully vested and expected to vest options outstanding that can be converted into shares under option plan. 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 exercise price, at which grantee can acquire shares reserved for issuance, for fully vested and expected to vest options outstanding. 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 price at which grantees could have acquired the underlying shares with respect to stock options of the plan that expired.

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Weighted average price at which grantees could have acquired the underlying shares with respect to stock options that were terminated.

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

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