v2.4.1.9
Marketable Securities (Available for Sale Securities Measured at Estimated Fair Value on Recurring Basis) (Details) (USD $)
In Thousands, unless otherwise specified
Mar. 28, 2015
Dec. 27, 2014
Schedule of Available-for-sale Securities [Line Items]    
Available-for-sale Securities, Total $ 1,529,314us-gaap_AvailableForSaleSecurities $ 1,575,333us-gaap_AvailableForSaleSecurities [1]
U.S. Treasury securities    
Schedule of Available-for-sale Securities [Line Items]    
Available-for-sale Securities, Total 27,369us-gaap_AvailableForSaleSecurities
/ us-gaap_InvestmentTypeAxis
= us-gaap_USTreasurySecuritiesMember
30,144us-gaap_AvailableForSaleSecurities
/ us-gaap_InvestmentTypeAxis
= us-gaap_USTreasurySecuritiesMember
[1]
Agency Securities    
Schedule of Available-for-sale Securities [Line Items]    
Available-for-sale Securities, Total 327,160us-gaap_AvailableForSaleSecurities
/ us-gaap_InvestmentTypeAxis
= us-gaap_AgencySecuritiesMember
428,320us-gaap_AvailableForSaleSecurities
/ us-gaap_InvestmentTypeAxis
= us-gaap_AgencySecuritiesMember
[1]
Mortgage-backed securities    
Schedule of Available-for-sale Securities [Line Items]    
Available-for-sale Securities, Total 380,535us-gaap_AvailableForSaleSecurities
/ us-gaap_InvestmentTypeAxis
= us-gaap_MortgageBackedSecuritiesMember
324,307us-gaap_AvailableForSaleSecurities
/ us-gaap_InvestmentTypeAxis
= us-gaap_MortgageBackedSecuritiesMember
[1]
Corporate securities    
Schedule of Available-for-sale Securities [Line Items]    
Available-for-sale Securities, Total 572,211us-gaap_AvailableForSaleSecurities
/ us-gaap_InvestmentTypeAxis
= us-gaap_CorporateBondSecuritiesMember
594,402us-gaap_AvailableForSaleSecurities
/ us-gaap_InvestmentTypeAxis
= us-gaap_CorporateBondSecuritiesMember
[1]
Municipal securities    
Schedule of Available-for-sale Securities [Line Items]    
Available-for-sale Securities, Total 153,617us-gaap_AvailableForSaleSecurities
/ us-gaap_InvestmentTypeAxis
= us-gaap_MunicipalNotesMember
125,410us-gaap_AvailableForSaleSecurities
/ us-gaap_InvestmentTypeAxis
= us-gaap_MunicipalNotesMember
[1]
Other    
Schedule of Available-for-sale Securities [Line Items]    
Available-for-sale Securities, Total 68,422us-gaap_AvailableForSaleSecurities
/ us-gaap_InvestmentTypeAxis
= grmn_OtherSecurityMember
72,750us-gaap_AvailableForSaleSecurities
/ us-gaap_InvestmentTypeAxis
= grmn_OtherSecurityMember
[1]
Level 1    
Schedule of Available-for-sale Securities [Line Items]    
Available-for-sale Securities, Total 0us-gaap_AvailableForSaleSecurities
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel1Member
0us-gaap_AvailableForSaleSecurities
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel1Member
[1]
Level 1 | U.S. Treasury securities    
Schedule of Available-for-sale Securities [Line Items]    
Available-for-sale Securities, Total 0us-gaap_AvailableForSaleSecurities
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel1Member
/ us-gaap_InvestmentTypeAxis
= us-gaap_USTreasurySecuritiesMember
0us-gaap_AvailableForSaleSecurities
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel1Member
/ us-gaap_InvestmentTypeAxis
= us-gaap_USTreasurySecuritiesMember
[1]
Level 1 | Agency Securities    
Schedule of Available-for-sale Securities [Line Items]    
Available-for-sale Securities, Total 0us-gaap_AvailableForSaleSecurities
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel1Member
/ us-gaap_InvestmentTypeAxis
= us-gaap_AgencySecuritiesMember
0us-gaap_AvailableForSaleSecurities
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel1Member
/ us-gaap_InvestmentTypeAxis
= us-gaap_AgencySecuritiesMember
[1]
Level 1 | Mortgage-backed securities    
Schedule of Available-for-sale Securities [Line Items]    
Available-for-sale Securities, Total 0us-gaap_AvailableForSaleSecurities
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel1Member
/ us-gaap_InvestmentTypeAxis
= us-gaap_MortgageBackedSecuritiesMember
0us-gaap_AvailableForSaleSecurities
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel1Member
/ us-gaap_InvestmentTypeAxis
= us-gaap_MortgageBackedSecuritiesMember
[1]
Level 1 | Corporate securities    
Schedule of Available-for-sale Securities [Line Items]    
Available-for-sale Securities, Total 0us-gaap_AvailableForSaleSecurities
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel1Member
/ us-gaap_InvestmentTypeAxis
= us-gaap_CorporateBondSecuritiesMember
0us-gaap_AvailableForSaleSecurities
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel1Member
/ us-gaap_InvestmentTypeAxis
= us-gaap_CorporateBondSecuritiesMember
[1]
Level 1 | Municipal securities    
Schedule of Available-for-sale Securities [Line Items]    
Available-for-sale Securities, Total 0us-gaap_AvailableForSaleSecurities
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel1Member
/ us-gaap_InvestmentTypeAxis
= us-gaap_MunicipalNotesMember
0us-gaap_AvailableForSaleSecurities
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel1Member
/ us-gaap_InvestmentTypeAxis
= us-gaap_MunicipalNotesMember
[1]
Level 1 | Other    
Schedule of Available-for-sale Securities [Line Items]    
Available-for-sale Securities, Total 0us-gaap_AvailableForSaleSecurities
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel1Member
/ us-gaap_InvestmentTypeAxis
= grmn_OtherSecurityMember
0us-gaap_AvailableForSaleSecurities
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel1Member
/ us-gaap_InvestmentTypeAxis
= grmn_OtherSecurityMember
[1]
Level 2    
Schedule of Available-for-sale Securities [Line Items]    
Available-for-sale Securities, Total 1,529,314us-gaap_AvailableForSaleSecurities
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel2Member
1,575,333us-gaap_AvailableForSaleSecurities
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel2Member
[1]
Level 2 | U.S. Treasury securities    
Schedule of Available-for-sale Securities [Line Items]    
Available-for-sale Securities, Total 27,369us-gaap_AvailableForSaleSecurities
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel2Member
/ us-gaap_InvestmentTypeAxis
= us-gaap_USTreasurySecuritiesMember
30,144us-gaap_AvailableForSaleSecurities
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel2Member
/ us-gaap_InvestmentTypeAxis
= us-gaap_USTreasurySecuritiesMember
[1]
Level 2 | Agency Securities    
Schedule of Available-for-sale Securities [Line Items]    
Available-for-sale Securities, Total 327,160us-gaap_AvailableForSaleSecurities
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel2Member
/ us-gaap_InvestmentTypeAxis
= us-gaap_AgencySecuritiesMember
428,320us-gaap_AvailableForSaleSecurities
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel2Member
/ us-gaap_InvestmentTypeAxis
= us-gaap_AgencySecuritiesMember
[1]
Level 2 | Mortgage-backed securities    
Schedule of Available-for-sale Securities [Line Items]    
Available-for-sale Securities, Total 380,535us-gaap_AvailableForSaleSecurities
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel2Member
/ us-gaap_InvestmentTypeAxis
= us-gaap_MortgageBackedSecuritiesMember
324,307us-gaap_AvailableForSaleSecurities
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel2Member
/ us-gaap_InvestmentTypeAxis
= us-gaap_MortgageBackedSecuritiesMember
[1]
Level 2 | Corporate securities    
Schedule of Available-for-sale Securities [Line Items]    
Available-for-sale Securities, Total 572,211us-gaap_AvailableForSaleSecurities
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel2Member
/ us-gaap_InvestmentTypeAxis
= us-gaap_CorporateBondSecuritiesMember
594,402us-gaap_AvailableForSaleSecurities
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel2Member
/ us-gaap_InvestmentTypeAxis
= us-gaap_CorporateBondSecuritiesMember
[1]
Level 2 | Municipal securities    
Schedule of Available-for-sale Securities [Line Items]    
Available-for-sale Securities, Total 153,617us-gaap_AvailableForSaleSecurities
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel2Member
/ us-gaap_InvestmentTypeAxis
= us-gaap_MunicipalNotesMember
125,410us-gaap_AvailableForSaleSecurities
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel2Member
/ us-gaap_InvestmentTypeAxis
= us-gaap_MunicipalNotesMember
[1]
Level 2 | Other    
Schedule of Available-for-sale Securities [Line Items]    
Available-for-sale Securities, Total 68,422us-gaap_AvailableForSaleSecurities
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel2Member
/ us-gaap_InvestmentTypeAxis
= grmn_OtherSecurityMember
72,750us-gaap_AvailableForSaleSecurities
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel2Member
/ us-gaap_InvestmentTypeAxis
= grmn_OtherSecurityMember
[1]
Level 3    
Schedule of Available-for-sale Securities [Line Items]    
Available-for-sale Securities, Total 0us-gaap_AvailableForSaleSecurities
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
0us-gaap_AvailableForSaleSecurities
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
[1]
Level 3 | U.S. Treasury securities    
Schedule of Available-for-sale Securities [Line Items]    
Available-for-sale Securities, Total 0us-gaap_AvailableForSaleSecurities
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
/ us-gaap_InvestmentTypeAxis
= us-gaap_USTreasurySecuritiesMember
0us-gaap_AvailableForSaleSecurities
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
/ us-gaap_InvestmentTypeAxis
= us-gaap_USTreasurySecuritiesMember
[1]
Level 3 | Agency Securities    
Schedule of Available-for-sale Securities [Line Items]    
Available-for-sale Securities, Total 0us-gaap_AvailableForSaleSecurities
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
/ us-gaap_InvestmentTypeAxis
= us-gaap_AgencySecuritiesMember
0us-gaap_AvailableForSaleSecurities
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
/ us-gaap_InvestmentTypeAxis
= us-gaap_AgencySecuritiesMember
[1]
Level 3 | Mortgage-backed securities    
Schedule of Available-for-sale Securities [Line Items]    
Available-for-sale Securities, Total 0us-gaap_AvailableForSaleSecurities
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
/ us-gaap_InvestmentTypeAxis
= us-gaap_MortgageBackedSecuritiesMember
0us-gaap_AvailableForSaleSecurities
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
/ us-gaap_InvestmentTypeAxis
= us-gaap_MortgageBackedSecuritiesMember
[1]
Level 3 | Corporate securities    
Schedule of Available-for-sale Securities [Line Items]    
Available-for-sale Securities, Total 0us-gaap_AvailableForSaleSecurities
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
/ us-gaap_InvestmentTypeAxis
= us-gaap_CorporateBondSecuritiesMember
0us-gaap_AvailableForSaleSecurities
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
/ us-gaap_InvestmentTypeAxis
= us-gaap_CorporateBondSecuritiesMember
[1]
Level 3 | Municipal securities    
Schedule of Available-for-sale Securities [Line Items]    
Available-for-sale Securities, Total 0us-gaap_AvailableForSaleSecurities
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
/ us-gaap_InvestmentTypeAxis
= us-gaap_MunicipalNotesMember
0us-gaap_AvailableForSaleSecurities
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
/ us-gaap_InvestmentTypeAxis
= us-gaap_MunicipalNotesMember
[1]
Level 3 | Other    
Schedule of Available-for-sale Securities [Line Items]    
Available-for-sale Securities, Total $ 0us-gaap_AvailableForSaleSecurities
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
/ us-gaap_InvestmentTypeAxis
= grmn_OtherSecurityMember
$ 0us-gaap_AvailableForSaleSecurities
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
/ us-gaap_InvestmentTypeAxis
= grmn_OtherSecurityMember
[1]
[1] Certain available-for-sale securities held as of December 27, 2014 have been reclassified among major security types to conform to the current year presentation. These reclassifications had no effect on fair value measurement.