GOODWILL AND OTHER INTANGIBLE ASSETS - Schedule of Intangible Assets (Details) - USD ($) $ in Thousands		3 Months Ended	12 Months Ended
	May 09, 2016	Sep. 30, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Sep. 15, 2017
Acquired Finite-Lived Intangible Assets [Line Items]
Fully Amortized Intangible Assets			$ 77,400
Gain (Loss) on Disposition of Intangible Assets			0	$ 17,149	$ 0
Proceeds from sale of intangible assets			1,500	18,333	0
Gross Carrying Value			107,570	147,194
Accumulated Amortization			62,169	127,998
Net Carrying Value			45,401	19,196
Disposition of Intangible Assets, Gross Consideration Received	$ 16,000
Professional Fees			700		$ 1,600
Customer relationships
Acquired Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value			16,200	56,749
Accumulated Amortization			11,700	46,513
Net Carrying Value			4,500	10,236
Merchant relationships
Acquired Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value			21,554	11,598
Accumulated Amortization			4,105	9,853
Net Carrying Value			17,449	1,745
Trade names
Acquired Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value			9,476	12,077
Accumulated Amortization			6,799	10,469
Net Carrying Value			2,677	1,608
Developed technology
Acquired Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value			13,825	36,864
Accumulated Amortization			13,485	36,864
Net Carrying Value			340	0
Patents
Acquired Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value			20,508	19,031
Accumulated Amortization			16,451	15,204
Net Carrying Value			4,057	3,827
Other Intangible Assets
Acquired Finite-Lived Intangible Assets [Line Items]
Gross Carrying Value			26,007	10,875
Accumulated Amortization			9,629	9,095
Net Carrying Value			$ 16,378	$ 1,780
OrderUp Intangible [Member]
Acquired Finite-Lived Intangible Assets [Line Items]
Gain (Loss) on Disposition of Intangible Assets		$ 17,100
Proceeds from sale of intangible assets		19,800
Disposition of Intangible Assets, Gross Consideration Received		20,000
Professional Fees		$ 200
Other Intangible Assets, Net						$ 2,700
Minimum
Acquired Finite-Lived Intangible Assets [Line Items]
Intangible assets, useful life			1 year
Maximum
Acquired Finite-Lived Intangible Assets [Line Items]
Intangible assets, useful life			10 years