GOODWILL (NARRATIVE) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Dec. 31, 2017
ValuationAllowanceForImpairmentOfRecognizedServicingAssetsLineItems
Goodwill	$ 205,632	$ 206,694
Impairment losses	1,120
Customer Management Services [Member]
ValuationAllowanceForImpairmentOfRecognizedServicingAssetsLineItems
Goodwill	118,336	119,497
Customer Strategy Services [Member]
ValuationAllowanceForImpairmentOfRecognizedServicingAssetsLineItems
Goodwill	22,018	21,919
Customer Growth Services [Member]
ValuationAllowanceForImpairmentOfRecognizedServicingAssetsLineItems
Goodwill	24,439	24,439
Customer Technology Services [Member]
ValuationAllowanceForImpairmentOfRecognizedServicingAssetsLineItems
Goodwill	$ 40,839	$ 40,839