BUSINESS COMBINATIONS - Allocation of purchase price and summary of estimated useful lives for Omnilink (Details) - USD ($)
$ in Thousands
May 05, 2014
Dec. 31, 2016
Dec. 31, 2015
Dec. 31, 2014
Business Acquisition [Line Items]        
Goodwill   $ 33,554 $ 43,424  
Trade names        
Business Acquisition [Line Items]        
Goodwill   $ 918 $ 2,972 $ 3,632
Omnilink Systems, Inc.        
Business Acquisition [Line Items]        
Cash $ 195      
Accounts receivable 2,677      
Inventory 873      
Prepaid and other assets 377      
Property and equipment 1,613      
Deferred tax asset 2,600      
Goodwill 17,318      
Total identifiable assets acquired 40,339      
Accounts payable (1,756)      
Accrued expenses (1,037)      
Deferred revenue (64)      
Total liabilities assumed (2,857)      
Net assets acquired $ 37,482      
Property and equipment, lives in years [1] 4 years      
Goodwill, lives in years Indefinite      
Omnilink Systems, Inc. | Customer Relationships        
Business Acquisition [Line Items]        
Software, trademarks, customer relationships and intangible assets $ 6,056      
Useful lives of intangible assets 11 years      
Omnilink Systems, Inc. | Technology        
Business Acquisition [Line Items]        
Software, trademarks, customer relationships and intangible assets $ 4,998      
Useful lives of intangible assets 14 years      
Omnilink Systems, Inc. | Trade names        
Business Acquisition [Line Items]        
Software, trademarks, customer relationships and intangible assets $ 3,632      
Estimated useful lives of acquired indefinite lived intangible assets Indefinite      
[1] The weighted average remaining useful life for all property and equipment is approximately four years.