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Goodwill - Additional Information (Detail)	Oct. 04, 2012
MVSD [Member]
Goodwill [Line Items]
Fair value in excess to carrying value	208.00%
SISD [Member]
Goodwill [Line Items]
Fair value in excess to carrying value	119.00%

X

- Definition

Fair value in excess to carrying value.

+ References

No definition available.

+ Details

Name:	cgnx_FairValueInExcessToCarryingValue
Namespace Prefix:	cgnx_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

X

- Details

Name:	us-gaap_GoodwillLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration