SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES , STOCK BASED COMPENSATION EXPENSE (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2019	Mar. 31, 2018
Stock-Based Compensation Expense [Abstract]
Compensation expense	$ 12,029	$ 10,412
Cost of Revenues [Member]
Stock-Based Compensation Expense [Abstract]
Compensation expense	2,058	1,431
Selling and Marketing (excluding customer base amortization) [Member]
Stock-Based Compensation Expense [Abstract]
Compensation expense	1,638	1,835
Software Development [Member]
Stock-Based Compensation Expense [Abstract]
Compensation expense	2,056	1,729
General and Administrative [Member]
Stock-Based Compensation Expense [Abstract]
Compensation expense	$ 6,277	$ 5,417

Represents the expense recognized during the period arising from equity-based compensation arrangements (for example, shares of stock, unit, stock options or other equity instruments) with employees, directors and certain consultants qualifying for treatment as employees.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=109197908&loc=d3e5047-113901

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SAB Topic 14.F)
-URI http://asc.fasb.org/extlink&oid=115993241&loc=d3e301413-122809

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (h)(1)(i)
-URI http://asc.fasb.org/extlink&oid=109197908&loc=d3e5070-113901

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration