Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

No definition available.

+ Details

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Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of increase (decrease) in the value of a contingent consideration liability, including, but not limited to, differences arising upon settlement.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 30
-Section 50
-Paragraph 4
-Subparagraph (a)(1)
-URI http://asc.fasb.org/extlink&oid=35744584&loc=d3e7008-128479

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Interest rate used to find the present value of an amount to be paid or received in the future as an input to measure fair value. For example, but not limited to, weighted average cost of capital (WACC), cost of capital, cost of equity and cost of debt.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (bbb)
-URI http://asc.fasb.org/extlink&oid=66048111&loc=d3e19207-110258

+ Details

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Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

The effective interest rate during the reporting period.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.19(b),22(b))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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Balance Type:	na
Period Type:	duration

- Details

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Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_BusinessAcquisitionAxis=ttec_SoficaMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_BusinessAcquisitionAxis=ttec_RogensiMember
Namespace Prefix:
Data Type:	na
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FAIR VALUE (NARRATIVE) (DETAILS) - USD ($) $ in Millions	3 Months Ended					12 Months Ended
FAIR VALUE (NARRATIVE) (DETAILS) - USD ($) $ in Millions	Dec. 31, 2017	Sep. 30, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Dec. 31, 2017	Dec. 31, 2016
Business acquisitions, Contingent Consideration [Line Items]
Average interest rate on annual borrowings						2.20%	1.50%
Iknowtion
Business acquisitions, Contingent Consideration [Line Items]
Discount rate						21.00%
Sofica [Member]
Business acquisitions, Contingent Consideration [Line Items]
Discount rate						5.00%
Increase (decrease) in contingent consideration payable					$ 0.5
rogenSi
Business acquisitions, Contingent Consideration [Line Items]
Discount rate						4.60%
Increase (decrease) in contingent consideration payable		$ 4.3	$ 0.3	$ 0.8
Atelka [Member]
Business acquisitions, Contingent Consideration [Line Items]
Discount rate						0.00%
Increase (decrease) in contingent consideration payable	$ 0.6