SHAREHOLDERS' EQUITY AND SHARE-BASED COMPENSATION - Stock option activity (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Number of options
Outstanding at the beginning of the period (in shares)	1,440,566
Performance criteria achieved (in shares)	227,849	277,000	244,000
Exercised (in shares)	(21,052)
Forfeited (in shares)	(179,317)
Outstanding at the end of the period (in shares)	1,468,046	1,440,566
Exercisable at the end of the period (in shares)	926,174
Weighted average exercise price
Outstanding at the beginning of the period (in dollars per share)	$ 30.78
Performance criteria achieved (in dollars per share)	24.98	$ 25.15	$ 33.28
Exercised (in dollars per share)	18.79
Forfeited (in dollars per share)	37.85
Outstanding at the end of the period (in dollars per share)	29.19	$ 30.78
Exercisable at the end of the period (in dollars per share)	$ 26.46
Weighted average contractual term (in years)
Weighted average contractual term	4 years 6 months 35 days	5 years 13 days
Exercisable at the end of the period	3 years 11 days
Aggregate intrinsic value (in thousands)
Aggregate intrinsic value (in dollars)	$ 94	$ 945
Exercisable at the end of the period (in dollars)	$ 92