STOCK-BASED COMPENSATION PLANS - Summary of total unrecognized compensation costs related to unvested stock-based compensation (Details 4) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation	$ 9,679
Weighted-average remaining recognition period (in years)	2 years 4 months 24 days
Stock Option
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation	6,113
Weighted-average remaining recognition period (in years)	2 years 7 months 6 days
Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation	$ 3,566
Weighted-average remaining recognition period (in years)	2 years