GOODWILL (NARRATIVE) (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2018	Dec. 31, 2017
ValuationAllowanceForImpairmentOfRecognizedServicingAssetsLineItems
Goodwill	$ 203,518	$ 206,694
Impairment losses	1,120
Customer Management Services [Member]
ValuationAllowanceForImpairmentOfRecognizedServicingAssetsLineItems
Goodwill	115,523	119,497
Customer Strategy Services [Member]
ValuationAllowanceForImpairmentOfRecognizedServicingAssetsLineItems
Goodwill	21,544	21,919
Customer Growth Services [Member]
ValuationAllowanceForImpairmentOfRecognizedServicingAssetsLineItems
Goodwill	24,439	24,439
Customer Technology Services [Member]
ValuationAllowanceForImpairmentOfRecognizedServicingAssetsLineItems
Goodwill	$ 42,012	$ 40,839