Employee Savings Plan	12 Months Ended
	Dec. 31, 2021
Retirement Benefits [Abstract]
Employee Savings Plan	Employee Savings PlanUnder the Company's Employee Savings Plan, a defined contribution plan, all U.S. employees who have attained age 21 may contribute up to 100% of their pay on a pre-tax basis under the Company's Employee Savings Plan, subject to the annual dollar limitations established by the Internal Revenue Service ("IRS"). The Company matches 50% of the first 6% of pay an employee contributes. Company contributions vest 25%, 50%, 75%, and 100% after one, two, three, and four years of continuous employment with the Company, respectively. Company contributions totaled $2,898,000 in 2021, $2,636,000 in 2020, and $2,729,000 in 2019. Cognex stock is not an investment alternative and Company contributions are not made in the form of Cognex stock.