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Document and Entity Information - shares
shares in Thousands
9 Months Ended
Sep. 29, 2018
Oct. 29, 2018
Document And Entity Information    
Entity Registrant Name GARMIN LTD  
Entity Central Index Key 0001121788  
Document Type 10-Q  
Trading Symbol GRMN  
Document Period End Date Sep. 29, 2018  
Amendment Flag false  
Current Fiscal Year End Date --12-29  
Entity Small Business false  
Entity Emerging Growth Company false  
Entity Ex Transition Period false  
Entity's Reporting Status Current Yes  
Entity Filer Category Large Accelerated Filer  
Entity Common Stock, Shares Outstanding   198,077,418
Document Fiscal Period Focus Q3  
Document Fiscal Year Focus 2018