SEGMENT INFORMATION (REVENUE GEOGRAPHY) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Revenues from External Customers and Long-Lived Assets [Line Items]
Sales Revenue Services Net	$ 2,273,062	$ 1,949,248	$ 1,643,704
Property, plant and equipment, gross	860,616	838,306	801,183
Other long-term assets	77,273	69,438	68,969
United States [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Sales Revenue Services Net	1,524,654	1,338,267	1,002,524
Property, plant and equipment, gross	605,582	576,803	559,326
Other long-term assets	67,291	55,548	57,417
Philippines [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Sales Revenue Services Net	409,360	347,575	370,395
Property, plant and equipment, gross	158,098	162,391	144,213
Other long-term assets	6,187	8,756	7,892
Latin America [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Sales Revenue Services Net	114,967	98,633	100,117
Property, plant and equipment, gross	47,540	46,307	45,743
Other long-term assets	864	912	993
Europe Middle East Africa [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Sales Revenue Services Net	110,909	78,478	70,613
Property, plant and equipment, gross	19,594	23,043	14,823
Other long-term assets	1,735	2,328	993
Asia Pacific[ Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Sales Revenue Services Net	67,035	59,750	55,554
Property, plant and equipment, gross	14,977	15,918	21,562
Other long-term assets	435	1,726	1,422
Canada [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Sales Revenue Services Net	46,137	26,545	44,501
Property, plant and equipment, gross	14,825	13,844	15,516
Other long-term assets	$ 761	$ 168	$ 252