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RESTRUCTURING AND INTEGRATION CHARGES AND IMPAIRMENT LOSSES (NARRATIVE) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020
Reduction in force					$ 443
Restructuring Reserve, Period Increase (Decrease)	$ 300
Facility exit charges	402				95
Restructuring reserve decrease
Restructuring Reserve, Period Increase (Decrease)	100
Leasehold Improvements
Restructuring impairment losses					700
TTEC Digital
Reduction in force					207
Facility exit charges	8
TTEC Engage
Reduction in force					236
Facility exit charges	394				$ 95
TTEC Engage \| Leasehold Improvements
Restructuring impairment losses	$ 2,400
Cost of Services
Restructuring Reserve, Period Increase (Decrease)		$ 300		$ 3,000
Cost of Services \| Restructuring reserve decrease
Restructuring Reserve, Period Increase (Decrease)			$ (1,600)