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Cash, Cash Equivalents, and Investments - Summary of Available-for-Sale Investments (Detail) (USD $) In Thousands, unless otherwise specified | Apr. 05, 2015
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Schedule of Available-for-sale Securities [Line Items] |
Amortized Cost | $ 509,924 us-gaap_AvailableForSaleDebtSecuritiesAmortizedCostBasis
Gross Unrealized Gains | 1,027 us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax
Gross Unrealized Losses | (131)us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax
Fair Value | 510,820 us-gaap_AvailableForSaleSecurities
Corporate Bonds |
Schedule of Available-for-sale Securities [Line Items] |
Gross Unrealized Losses | (110)us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_CorporateBondSecuritiesMember
Corporate Bonds | Short-Term Investments |
Schedule of Available-for-sale Securities [Line Items] |
Amortized Cost | 37,356 us-gaap_AvailableForSaleDebtSecuritiesAmortizedCostBasis / us-gaap_InvestmentTypeAxis = us-gaap_ShortTermInvestmentsMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_CorporateBondSecuritiesMember
Gross Unrealized Gains | 58 us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax / us-gaap_InvestmentTypeAxis = us-gaap_ShortTermInvestmentsMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_CorporateBondSecuritiesMember
Gross Unrealized Losses | (1)us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax / us-gaap_InvestmentTypeAxis = us-gaap_ShortTermInvestmentsMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_CorporateBondSecuritiesMember
Fair Value | 37,413 us-gaap_AvailableForSaleSecurities / us-gaap_InvestmentTypeAxis = us-gaap_ShortTermInvestmentsMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_CorporateBondSecuritiesMember
Corporate Bonds | Long-Term Investments |
Schedule of Available-for-sale Securities [Line Items] |
Amortized Cost | 203,712 us-gaap_AvailableForSaleDebtSecuritiesAmortizedCostBasis / us-gaap_InvestmentTypeAxis = cgnx_LongTermInvestmentsMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_CorporateBondSecuritiesMember
Gross Unrealized Gains | 618 us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax / us-gaap_InvestmentTypeAxis = cgnx_LongTermInvestmentsMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_CorporateBondSecuritiesMember
Gross Unrealized Losses | (109)us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax / us-gaap_InvestmentTypeAxis = cgnx_LongTermInvestmentsMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_CorporateBondSecuritiesMember
Fair Value | 204,221 us-gaap_AvailableForSaleSecurities / us-gaap_InvestmentTypeAxis = cgnx_LongTermInvestmentsMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_CorporateBondSecuritiesMember
Supranational bonds | Short-Term Investments |
Schedule of Available-for-sale Securities [Line Items] |
Amortized Cost | 1,900 us-gaap_AvailableForSaleDebtSecuritiesAmortizedCostBasis / us-gaap_InvestmentTypeAxis = us-gaap_ShortTermInvestmentsMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = cgnx_SupranationalbondsMember
Gross Unrealized Gains | 2 us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax / us-gaap_InvestmentTypeAxis = us-gaap_ShortTermInvestmentsMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = cgnx_SupranationalbondsMember
Gross Unrealized Losses | 0 us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax / us-gaap_InvestmentTypeAxis = us-gaap_ShortTermInvestmentsMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = cgnx_SupranationalbondsMember
Fair Value | 1,902 us-gaap_AvailableForSaleSecurities / us-gaap_InvestmentTypeAxis = us-gaap_ShortTermInvestmentsMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = cgnx_SupranationalbondsMember
Euro liquidity fund | Short-Term Investments |
Schedule of Available-for-sale Securities [Line Items] |
Amortized Cost | 61,866 us-gaap_AvailableForSaleDebtSecuritiesAmortizedCostBasis / us-gaap_InvestmentTypeAxis = us-gaap_ShortTermInvestmentsMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = cgnx_EuroliquidityfundMember
Gross Unrealized Gains | 179 us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax / us-gaap_InvestmentTypeAxis = us-gaap_ShortTermInvestmentsMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = cgnx_EuroliquidityfundMember
Gross Unrealized Losses | 0 us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax / us-gaap_InvestmentTypeAxis = us-gaap_ShortTermInvestmentsMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = cgnx_EuroliquidityfundMember
Fair Value | 62,045 us-gaap_AvailableForSaleSecurities / us-gaap_InvestmentTypeAxis = us-gaap_ShortTermInvestmentsMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = cgnx_EuroliquidityfundMember
Municipal Bonds | Short-Term Investments |
Schedule of Available-for-sale Securities [Line Items] |
Amortized Cost | 1,814 us-gaap_AvailableForSaleDebtSecuritiesAmortizedCostBasis / us-gaap_InvestmentTypeAxis = us-gaap_ShortTermInvestmentsMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_MunicipalBondsMember
Gross Unrealized Gains | 5 us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax / us-gaap_InvestmentTypeAxis = us-gaap_ShortTermInvestmentsMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_MunicipalBondsMember
Gross Unrealized Losses | 0 us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax / us-gaap_InvestmentTypeAxis = us-gaap_ShortTermInvestmentsMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_MunicipalBondsMember
Fair Value | 1,819 us-gaap_AvailableForSaleSecurities / us-gaap_InvestmentTypeAxis = us-gaap_ShortTermInvestmentsMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_MunicipalBondsMember
Municipal Bonds | Long-Term Investments |
Schedule of Available-for-sale Securities [Line Items] |
Amortized Cost | 4,855 us-gaap_AvailableForSaleDebtSecuritiesAmortizedCostBasis / us-gaap_InvestmentTypeAxis = cgnx_LongTermInvestmentsMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_MunicipalBondsMember
Gross Unrealized Gains | 25 us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax / us-gaap_InvestmentTypeAxis = cgnx_LongTermInvestmentsMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_MunicipalBondsMember
Gross Unrealized Losses | 0 us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax / us-gaap_InvestmentTypeAxis = cgnx_LongTermInvestmentsMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_MunicipalBondsMember
Fair Value | 4,880 us-gaap_AvailableForSaleSecurities / us-gaap_InvestmentTypeAxis = cgnx_LongTermInvestmentsMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_MunicipalBondsMember
Sovereign Bonds | Short-Term Investments |
Schedule of Available-for-sale Securities [Line Items] |
Amortized Cost | 5,594 us-gaap_AvailableForSaleDebtSecuritiesAmortizedCostBasis / us-gaap_InvestmentTypeAxis = us-gaap_ShortTermInvestmentsMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_SovereignDebtSecuritiesMember
Gross Unrealized Gains | 11 us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax / us-gaap_InvestmentTypeAxis = us-gaap_ShortTermInvestmentsMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_SovereignDebtSecuritiesMember
Gross Unrealized Losses | 0 us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax / us-gaap_InvestmentTypeAxis = us-gaap_ShortTermInvestmentsMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_SovereignDebtSecuritiesMember
Fair Value | 5,605 us-gaap_AvailableForSaleSecurities / us-gaap_InvestmentTypeAxis = us-gaap_ShortTermInvestmentsMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_SovereignDebtSecuritiesMember
Sovereign Bonds | Long-Term Investments |
Schedule of Available-for-sale Securities [Line Items] |
Amortized Cost | 6,033 us-gaap_AvailableForSaleDebtSecuritiesAmortizedCostBasis / us-gaap_InvestmentTypeAxis = cgnx_LongTermInvestmentsMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_SovereignDebtSecuritiesMember
Gross Unrealized Gains | 7 us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax / us-gaap_InvestmentTypeAxis = cgnx_LongTermInvestmentsMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_SovereignDebtSecuritiesMember
Gross Unrealized Losses | 0 us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax / us-gaap_InvestmentTypeAxis = cgnx_LongTermInvestmentsMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_SovereignDebtSecuritiesMember
Fair Value | 6,040 us-gaap_AvailableForSaleSecurities / us-gaap_InvestmentTypeAxis = cgnx_LongTermInvestmentsMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_SovereignDebtSecuritiesMember
Asset-Backed Securities |
Schedule of Available-for-sale Securities [Line Items] |
Gross Unrealized Losses | (12)us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_AssetBackedSecuritiesMember
Asset-Backed Securities | Short-Term Investments |
Schedule of Available-for-sale Securities [Line Items] |
Amortized Cost | 392 us-gaap_AvailableForSaleDebtSecuritiesAmortizedCostBasis / us-gaap_InvestmentTypeAxis = us-gaap_ShortTermInvestmentsMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_AssetBackedSecuritiesMember
Gross Unrealized Gains | 0 us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax / us-gaap_InvestmentTypeAxis = us-gaap_ShortTermInvestmentsMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_AssetBackedSecuritiesMember
Gross Unrealized Losses | 0 us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax / us-gaap_InvestmentTypeAxis = us-gaap_ShortTermInvestmentsMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_AssetBackedSecuritiesMember
Fair Value | 392 us-gaap_AvailableForSaleSecurities / us-gaap_InvestmentTypeAxis = us-gaap_ShortTermInvestmentsMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_AssetBackedSecuritiesMember
Asset-Backed Securities | Long-Term Investments |
Schedule of Available-for-sale Securities [Line Items] |
Amortized Cost | 77,417 us-gaap_AvailableForSaleDebtSecuritiesAmortizedCostBasis / us-gaap_InvestmentTypeAxis = cgnx_LongTermInvestmentsMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_AssetBackedSecuritiesMember
Gross Unrealized Gains | 43 us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax / us-gaap_InvestmentTypeAxis = cgnx_LongTermInvestmentsMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_AssetBackedSecuritiesMember
Gross Unrealized Losses | (12)us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax / us-gaap_InvestmentTypeAxis = cgnx_LongTermInvestmentsMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_AssetBackedSecuritiesMember
Fair Value | 77,448 us-gaap_AvailableForSaleSecurities / us-gaap_InvestmentTypeAxis = cgnx_LongTermInvestmentsMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_AssetBackedSecuritiesMember
Treasury Bills |
Schedule of Available-for-sale Securities [Line Items] |
Gross Unrealized Losses | (9)us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_USTreasurySecuritiesMember
Treasury Bills | Short-Term Investments |
Schedule of Available-for-sale Securities [Line Items] |
Amortized Cost | 31,652 us-gaap_AvailableForSaleDebtSecuritiesAmortizedCostBasis / us-gaap_InvestmentTypeAxis = us-gaap_ShortTermInvestmentsMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_USTreasurySecuritiesMember
Gross Unrealized Gains | 0 us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax / us-gaap_InvestmentTypeAxis = us-gaap_ShortTermInvestmentsMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_USTreasurySecuritiesMember
Gross Unrealized Losses | (8)us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax / us-gaap_InvestmentTypeAxis = us-gaap_ShortTermInvestmentsMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_USTreasurySecuritiesMember
Fair Value | 31,644 us-gaap_AvailableForSaleSecurities / us-gaap_InvestmentTypeAxis = us-gaap_ShortTermInvestmentsMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_USTreasurySecuritiesMember
Treasury Bills | Long-Term Investments |
Schedule of Available-for-sale Securities [Line Items] |
Amortized Cost | 64,468 us-gaap_AvailableForSaleDebtSecuritiesAmortizedCostBasis / us-gaap_InvestmentTypeAxis = cgnx_LongTermInvestmentsMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_USTreasurySecuritiesMember
Gross Unrealized Gains | 57 us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax / us-gaap_InvestmentTypeAxis = cgnx_LongTermInvestmentsMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_USTreasurySecuritiesMember
Gross Unrealized Losses | (1)us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax / us-gaap_InvestmentTypeAxis = cgnx_LongTermInvestmentsMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_USTreasurySecuritiesMember
Fair Value | 64,524 us-gaap_AvailableForSaleSecurities / us-gaap_InvestmentTypeAxis = cgnx_LongTermInvestmentsMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_USTreasurySecuritiesMember
Agency Bonds | Short-Term Investments |
Schedule of Available-for-sale Securities [Line Items] |
Amortized Cost | 1,521 us-gaap_AvailableForSaleDebtSecuritiesAmortizedCostBasis / us-gaap_InvestmentTypeAxis = us-gaap_ShortTermInvestmentsMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = cgnx_AgencyBondsMember
Gross Unrealized Gains | 2 us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax / us-gaap_InvestmentTypeAxis = us-gaap_ShortTermInvestmentsMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = cgnx_AgencyBondsMember
Gross Unrealized Losses | 0 us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax / us-gaap_InvestmentTypeAxis = us-gaap_ShortTermInvestmentsMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = cgnx_AgencyBondsMember
Fair Value | 1,523 us-gaap_AvailableForSaleSecurities / us-gaap_InvestmentTypeAxis = us-gaap_ShortTermInvestmentsMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = cgnx_AgencyBondsMember
Agency Bonds | Long-Term Investments |
Schedule of Available-for-sale Securities [Line Items] |
Amortized Cost | 11,344 us-gaap_AvailableForSaleDebtSecuritiesAmortizedCostBasis / us-gaap_InvestmentTypeAxis = cgnx_LongTermInvestmentsMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = cgnx_AgencyBondsMember
Gross Unrealized Gains | 20 us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax / us-gaap_InvestmentTypeAxis = cgnx_LongTermInvestmentsMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = cgnx_AgencyBondsMember
Gross Unrealized Losses | 0 us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax / us-gaap_InvestmentTypeAxis = cgnx_LongTermInvestmentsMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = cgnx_AgencyBondsMember
Fair Value | $ 11,364 us-gaap_AvailableForSaleSecurities / us-gaap_InvestmentTypeAxis = cgnx_LongTermInvestmentsMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = cgnx_AgencyBondsMember

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- Definition Amount before tax of unrealized gain in accumulated other comprehensive income (AOCI) on investments in debt securities classified as available-for-sale. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27161-111563 + Details
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