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Document and Entity Information - shares
shares in Thousands
6 Months Ended
Jun. 30, 2018
Jul. 30, 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 Jun. 30, 2018  
Amendment Flag false  
Current Fiscal Year End Date --12-29  
Entity a Well-known Seasoned Issuer No  
Entity a Voluntary Filer No  
Entity's Reporting Status Current Yes  
Entity Filer Category Large Accelerated Filer  
Entity Common Stock, Shares Outstanding   198,077,418
Document Fiscal Period Focus Q2  
Document Fiscal Year Focus 2018