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STOCK-BASED COMPENSATION (Narrative) (Details) - USD ($)	1 Months Ended	12 Months Ended			132 Months Ended
	May 31, 2014	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2019	Dec. 31, 2008	Dec. 31, 2004
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Allocated share-based compensation expense		$ 6,152,000	$ 5,249,000	$ 4,808,000
Stock-based compensation expense		5,008,000			$ 5,008,000
Intrinsic value of options exercised		$ 2,055,000	$ 5,850,000	3,159,000
Employee Stock Award Plan-2008
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of authorized shares available for future issuance (in shares)		834,910	890,857		834,910	1,900,000
Additional shares authorized (in shares)	1,500,000	0			1,500,000
Award expiration term		10 years
Employee Stock Award Plan-2008 \| Tranche one
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of option awards vest and exercisable in installments		20.00%
Employee Stock Award Plan-2008 \| Tranche two
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Percentage of option awards vest and exercisable in installments		33.30%
Director Plan - 2005
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of authorized shares available for future issuance (in shares)		34,863	49,163		34,863		300,000
Restricted Stock Awards \| Employee Stock Award Plan-2008 \| Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period of restricted stock awards		3 years
Restricted Stock Awards \| Employee Stock Award Plan-2008 \| Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period of restricted stock awards		5 years
Restricted Stock Awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Allocated share-based compensation expense		$ 4,659,000	$ 3,877,000	$ 2,987,000
Total compensation expense that has yet to be recognized		3,512			$ 3,512
Intrinsic value of the unvested restricted stock awards outstanding		$ 10,165,000	$ 15,746,000		$ 10,165,000