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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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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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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For presentations that combine terminations, 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 or that expired.

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

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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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STOCKHOLDERS' EQUITY - Stock Options (Details) - USD ($)	3 Months Ended			6 Months Ended		9 Months Ended	12 Months Ended
	Sep. 30, 2018	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Sep. 30, 2018	Dec. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Granted (in shares)	0	0	0	0	0	0
Options
Outstanding at period start (in shares)				176,959		176,959
Exercised (in shares)						(11,533)
Forfeited or expired (in shares)						(50,652)
Outstanding at period end (in shares)	114,774					114,774	176,959
Weighted-Average Exercise Price
Outstanding at period start, Weighted-Average Exercise Price (in dollars per share)				$ 29.42		$ 29.42
Exercised, Weighted-Average Exercise Price (in dollars per share)						29.29
Forfeited or expired, Weighted-Average Exercise Price (in dollars per share)						27.61
Outstanding at period end, Weighted-Average Exercise Price (in dollars per share)	$ 30.33					$ 30.33	$ 29.42
Contractual Terms (in years)						2 years 1 month 6 days	2 years
Stock Option
Weighted-Average Exercise Price
Vesting period (in years)						3 years
Stock-based compensation expense			$ 0	$ 0	$ 0