STOCK-BASED COMPENSATION PLANS - Summary of activity of stock options (Details) - Stock Options - $ / shares shares in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Shares Under Option
Outstanding at Beginning of Period	37	38	72
Granted	0	0	0
Exercised	(26)	(1)	(34)
Forfeited and cancelled	0	0	0
Outstanding at End of Period	11	37	38
Options exercisable at year end	11	37	38
Weighted Average Exercise Price
Outstanding at Beginning of Period	$ 5.49	$ 5.49	$ 5.49
Granted	0.00	0.00	0.00
Exercised	5.49	5.49	5.49
Forfeited and cancelled	0.00	0.00	0.00
Outstanding at End of Period	5.49	5.49	5.49
Options exercisable at year end	$ 5.49	$ 5.49	$ 5.49