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RESTRUCTURING AND INTEGRATION CHARGES AND IMPAIRMENT LOSSES (NARRATIVE) (Details) - USD ($)	3 Months Ended			6 Months Ended
	Jun. 30, 2021	Dec. 31, 2020	Jun. 30, 2020	Jun. 30, 2021	Dec. 31, 2020	Jun. 30, 2020
Reduction in force	$ 800,000		$ 117,000	$ 800,000		$ 560,000
Restructuring Reserve, Period Increase (Decrease)				400,000
Facility exit charges	925,000		676,000	1,327,000		771,000
Restructuring reserve decrease
Restructuring Reserve, Period Increase (Decrease)				600,000
Leasehold Improvements
Restructuring impairment losses			0	700,000		700,000
TTEC Digital
Reduction in force	858,000		114,000	858,000		321,000
Facility exit charges				8,000
TTEC Engage
Reduction in force	(58,000)		3,000	(58,000)		239,000
Facility exit charges	925,000		676,000	$ 1,319,000		$ 771,000
TTEC Engage \| Leasehold Improvements
Restructuring impairment losses	$ 200,000
Cost of Services
Restructuring Reserve, Period Increase (Decrease)		$ 300,000	$ 3,000,000.0
Cost of Services \| Restructuring reserve decrease
Restructuring Reserve, Period Increase (Decrease)					$ (1,600,000)