INTANGIBLE ASSETS - Summary of intangible assets other than goodwill (Details) (USD $)
In Thousands, unless otherwise specified
3 Months Ended
Mar. 31, 2014
Dec. 31, 2013
Finite-Lived Intangible Assets [Line Items]    
Gross Carrying Amount $ 29,804 $ 28,893
Accumulated Amortization (17,936) (16,895)
Net Book Value 11,868 11,998
Purchased and developed software
   
Finite-Lived Intangible Assets [Line Items]    
Weighted Remaining Average Useful Lives 2 years  
Gross Carrying Amount 9,361 8,836
Accumulated Amortization (4,362) (3,706)
Net Book Value 4,999 5,130
Patents and trademarks
   
Finite-Lived Intangible Assets [Line Items]    
Weighted Remaining Average Useful Lives 4 years 9 months 18 days  
Gross Carrying Amount 3,260 3,260
Accumulated Amortization (1,295) (1,172)
Net Book Value 1,965 2,088
Customer relationships
   
Finite-Lived Intangible Assets [Line Items]    
Weighted Remaining Average Useful Lives 4 years 4 months 24 days  
Gross Carrying Amount 2,231 2,231
Accumulated Amortization (699) (602)
Net Book Value 1,532 1,629
Licenses and other intangible assets
   
Finite-Lived Intangible Assets [Line Items]    
Weighted Remaining Average Useful Lives 1 year 4 months 24 days  
Gross Carrying Amount 12,728 12,646
Accumulated Amortization (11,580) (11,415)
Net Book Value 1,148 1,231
Software and other intangible assets in development and not in service
   
Finite-Lived Intangible Assets [Line Items]    
Gross Carrying Amount 2,224 1,920
Accumulated Amortization      
Net Book Value $ 2,224 $ 1,920