SEGMENT INFORMATION (REVENUE GEOGRAPHY) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	$ 394,356	$ 375,249
United States [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	236,967	209,848
Philippines [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	93,179	89,205
Latin America [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	24,135	30,498
Europe Middle East Africa [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	16,041	15,971
Asia Pacific India[ Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	12,826	13,437
Canada [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	$ 11,208	$ 16,290