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RESTRUCTURING AND INTEGRATION CHARGES AND IMPAIRMENT LOSSES (NARRATIVE) (Details) - USD ($) $ in Thousands	3 Months Ended			9 Months Ended
	Sep. 30, 2020	Jun. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Reduction in force	$ 347		$ 90	$ 907	$ 860
Facility exit charges	886		93	1,657	712
Leasehold Improvements
Restructuring impairment losses			0		2,600
TTEC Digital
Reduction in force	347		90	668	90
Facility exit charges	90		8	90	8
TTEC Engage
Reduction in force				239	770
Facility exit charges	796		$ 85	1,567	$ 704
TTEC Engage \| Leasehold Improvements
Restructuring impairment losses	900			$ 1,600
Cost of Services
Restructuring Reserve, Period Increase (Decrease)	100	$ 2,900
Cost of Services \| Restructuring reserve decrease
Restructuring Reserve, Period Increase (Decrease)	$ (500)