SEGMENT INFORMATION (REVENUE GEOGRAPHY) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020	Dec. 31, 2020
Revenues from External Customers and Long-Lived Assets [Line Items]
Sales Revenue Services Net	$ 554,794	$ 453,081	$ 1,094,013	$ 885,294
Other long-term assets	74,048		74,048		$ 69,438
United States [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Sales Revenue Services Net	372,851	312,310	731,180	589,988
Philippines [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Sales Revenue Services Net	102,472	79,269	204,724	170,373
Latin America [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Sales Revenue Services Net	27,354	23,352	56,791	48,450
Europe Middle East Africa [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Sales Revenue Services Net	27,640	17,361	53,557	34,304
Asia Pacific India[ Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Sales Revenue Services Net	16,404	13,725	32,571	28,893
Canada [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Sales Revenue Services Net	$ 8,073	$ 7,064	$ 15,190	$ 13,286