STOCK-BASED COMPENSATION - Stock Options and Stock Appreciation Rights Grants and Liability (Details) - shares	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Stock-based compensation
Granted (in shares)	33,157
2001 Stock Option Plan \| Stock Options and Stock Appreciation Rights
Stock-based compensation
Granted (in shares)	0	0	0

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