GOODWILL (GOODWILL ROLLFORWARD) (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019
Goodwill [Line Items]
Beginning balance, goodwill	$ 301,694	$ 204,633
Acquisitions / Adjustments Increase (Decrease)	59,087	96,993
Effect of Foreign Currency	2,721	68
Ending balance, goodwill	363,502	301,694
TTEC Digital
Goodwill [Line Items]
Beginning balance, goodwill	66,275	66,158
Acquisitions / Adjustments Increase (Decrease)	59,341	0
Effect of Foreign Currency	2,595	117
Ending balance, goodwill	128,211	66,275
TTEC Engage
Goodwill [Line Items]
Beginning balance, goodwill	235,419	138,475
Acquisitions / Adjustments Increase (Decrease)	(254)	96,993
Effect of Foreign Currency	126	(49)
Ending balance, goodwill	$ 235,291	$ 235,419

Amount after accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(10)(1))
-URI http://asc.fasb.org/extlink&oid=120398452&loc=d3e534808-122878

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 20
-Section 45
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Amount of foreign currency translation gain (loss) which increases (decreases) an asset representing future economic benefits from other assets acquired in a business combination that are not individually identified and separately recognized.

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Amount of increase (decrease), classified as other, of an asset representing the future economic benefits from other assets acquired in a business combination that are not individually identified and separately recognized.

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