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Contingencies - Additional Information (Detail) | 1 Months Ended
--- | ---
Jul. 31, 2010 Patents | Dec. 31, 2009 Respondent | Sep. 30, 2009 Respondent
Leases [Abstract] |  |  |
Number of respondents with whom a settlement was reached |  | 5 | 2
Number of the company's patents found invalid | 2 |  |

X
- Definition Number of company's patents found invalid. + References No definition available. + Details
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Namespace Prefix: | cgnx_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

X
- Definition Number of respondents with whom a settlement was reached. + References No definition available. + Details
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Namespace Prefix: | cgnx_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

X
- Details
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Namespace Prefix: | us-gaap_
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Balance Type: | na
Period Type: | duration