GOODWILL AND OTHER INTANGIBLE ASSETS - Schedule of Intangible Assets (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Acquired Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value	$ 149,039	$ 147,194
Accumulated Amortization	132,114	127,998
Net Carrying Value	16,925	19,196
Customer relationships
Acquired Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value	57,573	56,749
Accumulated Amortization	48,845	46,513
Net Carrying Value	8,728	10,236
Merchant relationships
Acquired Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value	11,755	11,598
Accumulated Amortization	10,302	9,853
Net Carrying Value	1,453	1,745
Trade names
Acquired Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value	12,212	12,077
Accumulated Amortization	10,891	10,469
Net Carrying Value	1,321	1,608
Developed technology
Acquired Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value	37,045	36,864
Accumulated Amortization	37,045	36,864
Net Carrying Value	0	0
Patents
Acquired Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value	19,697	19,031
Accumulated Amortization	15,563	15,204
Net Carrying Value	4,134	3,827
Other intangible assets
Acquired Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value	10,757	10,875
Accumulated Amortization	9,468	9,095
Net Carrying Value	$ 1,289	$ 1,780