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Document and Entity Information - USD ($)
$ in Thousands
12 Months Ended
Dec. 29, 2018
Feb. 15, 2019
Jun. 30, 2018
Document And Entity Information      
Entity Registrant Name GARMIN LTD    
Entity Central Index Key 0001121788    
Document Type 10-K    
Trading Symbol GRMN    
Document Period End Date Dec. 29, 2018    
Amendment Flag false    
Current Fiscal Year End Date --12-29    
Entity a Well-known Seasoned Issuer Yes    
Entity a Voluntary Filer No    
Entity's Reporting Status Current Yes    
Entity Small Business false    
Entity Filer Category Large Accelerated Filer    
Entity Emerging Growth Company false    
Entity Ex Transition Period false    
Entity Shell Company false    
Entity Public Float     $ 7,753,502,173
Entity Common Stock, Shares Outstanding   198,077,418  
Document Fiscal Period Focus FY    
Document Fiscal Year Focus 2018