Summary of Significant Accounting Policies	6 Months Ended
Summary of Significant Accounting Policies	Jul. 03, 2011
Summary of Significant Accounting Policies [Abstract]
Summary of Significant Accounting Policies	NOTE 1: Summary of Significant Accounting Policies As permitted by the rules of the Securities and Exchange Commission applicable to Quarterly Reports on Form 10-Q, these notes are condensed and do not contain all disclosures required by generally accepted accounting principles (GAAP). Reference should be made to the consolidated financial statements and related notes included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2010. In the opinion of the management of Cognex Corporation (the “Company”), the accompanying consolidated unaudited financial statements contain all adjustments, consisting of normal, recurring adjustments necessary to present fairly the Company’s financial position as of July 3, 2011, and the results of its operations for the three-month and six-month periods ended July 3, 2011 and July 4, 2010, and changes in shareholders’ equity and cash flows for the periods presented. The results disclosed in the Consolidated Statements of Operations for the three-month and six-month periods ended July 3, 2011 are not necessarily indicative of the results to be expected for the full year.

The entire disclosure for all significant accounting policies of the reporting entity.