Intangible Assets - Additional Information (Detail) (USD $)	Dec. 31, 2012
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cost and related amortization finite lived intangible Assets	$ 8,535,000

Finite lived intangible assets cost and accumulated amortization removed.

No definition available.

Name:	cgnx_FiniteLivedIntangibleAssetsCostAndAccumulatedAmortizationRemoved
Namespace Prefix:	cgnx_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant