SHARE-BASED COMPENSATION - Summary of Activity of Non-Performance-Based & Performance-Based Options (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Stock Option Activity, Shares
Granted (in shares)	0	0	0
Non-Performance-Based
Stock Option Activity, Shares
Under option, beginning of year (in shares)	58,603	72,483	88,111
Granted (in shares)	0	0	0
Exercised (in shares)	(11,309)	(13,880)	(15,628)
Forfeited (in shares)	0	0	0
Under option, end of year (in shares)	47,294	58,603	72,483
Exercisable at end of year (in shares)	47,294	58,603	72,483
Stock Options Weighted Average Exercise Price
Under option, beginning of year, Weighted-Average Exercise Price (in dollars per share)	$ 14.76	$ 18.55	$ 18.00
Granted, Weighted-Average Exercise Price (in dollars per share)	0.00	0.00	0.00
Exercised, Weighted-Average Exercise Price (in dollars per share)	14.76	14.38	15.47
Forfeited, Weighted-Average Exercise Price (in dollars per share)	0.00	0.00	0.00
Under option, end of year, Weighted-Average Exercise Price (in dollars per share)	14.76	14.76	18.55
Exercisable at end of year, Weighted-Average Exercise Price (in dollars per share)	$ 14.76	$ 14.76	$ 18.55
Stock Option Activity, Additional Disclosures
Under option, end of year, Weighted Average Contractual Term	1 month 20 days	1 year 1 month 20 days	2 years 1 month 17 days
Exercisable at end of year, Weighted Average Contractual Term	1 month 20 days	1 year 1 month 20 days	2 years 1 month 17 days
Exercised, Aggregate Intrinsic Value	$ 167	$ 200	$ 242
Under option, end of year, Aggregate Intrinsic Value	1,519	1,620	1,331
Exercisable at end of year, Aggregate Intrinsic Value	$ 1,519	$ 1,620	$ 1,331
Performance-Based
Stock Option Activity, Shares
Under option, beginning of year (in shares)	142,910	224,132	359,331
Granted (in shares)	0	0	0
Exercised (in shares)	(102,309)	(40,714)	(59,507)
Forfeited (in shares)	(3,588)	(40,508)	(75,691)
Under option, end of year (in shares)	37,013	142,910	224,132
Exercisable at end of year (in shares)	37,013	142,910	189,587
Stock Options Weighted Average Exercise Price
Under option, beginning of year, Weighted-Average Exercise Price (in dollars per share)	$ 15.06	$ 16.92	$ 16.74
Granted, Weighted-Average Exercise Price (in dollars per share)	0.00	0.00	0.00
Exercised, Weighted-Average Exercise Price (in dollars per share)	17.62	14.68	15.39
Forfeited, Weighted-Average Exercise Price (in dollars per share)	21.35	19.67	17.37
Under option, end of year, Weighted-Average Exercise Price (in dollars per share)	7.36	15.06	16.92
Exercisable at end of year, Weighted-Average Exercise Price (in dollars per share)	$ 7.36	$ 15.06	$ 15.91
Stock Option Activity, Additional Disclosures
Under option, end of year, Weighted Average Contractual Term	1 year 25 days	1 year 2 months 19 days	1 year 9 months 18 days
Exercisable at end of year, Weighted Average Contractual Term	1 year 25 days	1 year 2 months 19 days	2 years 22 days
Exercised, Aggregate Intrinsic Value	$ 1,803	$ 765	$ 916
Under option, end of year, Aggregate Intrinsic Value	1,463	3,909	3,697
Exercisable at end of year, Aggregate Intrinsic Value	$ 1,463	$ 3,909	$ 3,252