Revenue - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018
Deferred Revenue And Customer Advances	$ 65.6	$ 69.9
Short-term Contract with Customer [Member]
Revenue, Remaining Performance Obligation, Percentage	70.00%
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction Period	12 months
Long-term Contract with Customer [Member]
Revenue, Remaining Performance Obligation, Percentage	26.00%
Long-term Contract with Customer [Member] \| Maximum [Member]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction Period	3 years
Long-term Contract with Customer [Member] \| Minimum [Member]
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction Period	1 year

Period in which remaining performance obligation is expected to be recognized as revenue, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

No definition available.

+ Details

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Namespace Prefix:	ter_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of revenue recognized that was previously included in balance of obligation to transfer good or service to customer for which consideration from customer has been received or is due.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 8
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=118956577&loc=SL49130549-203045

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Percentage of remaining performance obligation to total remaining performance obligation not recognized as revenue.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 13
-Subparagraph (b)(1)
-URI http://asc.fasb.org/extlink&oid=118956577&loc=SL49130556-203045

+ Details

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- Details

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- Details

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- Details

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- Details

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