Marketable Securities (Available for Sale Securities Measured at Estimated Fair Value on Recurring Basis) (Details) (USD $) In Thousands, unless otherwise specified
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Mar. 28, 2015
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Dec. 27, 2014
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Schedule of Available-for-sale Securities [Line Items] |
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Available-for-sale Securities, Total |
$ 1,529,314us-gaap_AvailableForSaleSecurities |
$ 1,575,333us-gaap_AvailableForSaleSecurities |
[1] |
U.S. Treasury securities |
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Schedule of Available-for-sale Securities [Line Items] |
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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 |
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Schedule of Available-for-sale Securities [Line Items] |
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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 |
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Schedule of Available-for-sale Securities [Line Items] |
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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 |
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Schedule of Available-for-sale Securities [Line Items] |
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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 |
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Schedule of Available-for-sale Securities [Line Items] |
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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 |
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Schedule of Available-for-sale Securities [Line Items] |
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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 |
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Schedule of Available-for-sale Securities [Line Items] |
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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 |
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Schedule of Available-for-sale Securities [Line Items] |
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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 |
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Schedule of Available-for-sale Securities [Line Items] |
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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 |
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Schedule of Available-for-sale Securities [Line Items] |
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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 |
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Schedule of Available-for-sale Securities [Line Items] |
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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 |
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Schedule of Available-for-sale Securities [Line Items] |
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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 |
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Schedule of Available-for-sale Securities [Line Items] |
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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 |
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Schedule of Available-for-sale Securities [Line Items] |
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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 |
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Schedule of Available-for-sale Securities [Line Items] |
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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 |
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Schedule of Available-for-sale Securities [Line Items] |
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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 |
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Schedule of Available-for-sale Securities [Line Items] |
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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 |
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Schedule of Available-for-sale Securities [Line Items] |
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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 |
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Schedule of Available-for-sale Securities [Line Items] |
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|
|
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 |
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Schedule of Available-for-sale Securities [Line Items] |
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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 |
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Schedule of Available-for-sale Securities [Line Items] |
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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 |
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Schedule of Available-for-sale Securities [Line Items] |
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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 |
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Schedule of Available-for-sale Securities [Line Items] |
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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 |
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Schedule of Available-for-sale Securities [Line Items] |
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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 |
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Schedule of Available-for-sale Securities [Line Items] |
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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 |
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Schedule of Available-for-sale Securities [Line Items] |
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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 |
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Schedule of Available-for-sale Securities [Line Items] |
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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] |
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