Quarterly report pursuant to Section 13 or 15(d)

Marketable Securities (Details)

v2.4.1.9
Marketable Securities (Details) (USD $)
3 Months Ended
Dec. 28, 2014
Dec. 29, 2013
Sep. 28, 2014
Schedule of Marketable Securities [Line Items]      
Restricted Cash and Cash Equivalents, Current $ 38,000,000us-gaap_RestrictedCashAndCashEquivalentsAtCarryingValue    
Foreign Currency Exchange Rate, Remeasurement 1.51571us-gaap_ForeignCurrencyExchangeRateRemeasurement1    
Total marketable securities - Current 11,463,000,000us-gaap_MarketableSecuritiesCurrent   9,658,000,000us-gaap_MarketableSecuritiesCurrent
Total marketable securities - Noncurrent 13,815,000,000us-gaap_MarketableSecuritiesNoncurrent   14,457,000,000us-gaap_MarketableSecuritiesNoncurrent
Trading Securities [Abstract]      
Trading - Current 509,000,000us-gaap_TradingSecurities   511,000,000us-gaap_TradingSecurities
Trading - Noncurrent 621,000,000qcom_TradingSecuritiesNoncurrent   642,000,000qcom_TradingSecuritiesNoncurrent
Net losses recognized on debt securities classified as trading held at the end of the period 12,000,000us-gaap_TradingSecuritiesUnrealizedHoldingGainLoss 0us-gaap_TradingSecuritiesUnrealizedHoldingGainLoss  
Available-for-sale Securities [Abstract]      
Available-for-sale - Current 10,954,000,000us-gaap_AvailableForSaleSecuritiesCurrent   9,147,000,000us-gaap_AvailableForSaleSecuritiesCurrent
Available-for-sale - Noncurrent 12,410,000,000us-gaap_AvailableForSaleSecuritiesNoncurrent   13,025,000,000us-gaap_AvailableForSaleSecuritiesNoncurrent
Fair Value Option [Abstract]      
Effective ownership interest in debt fund (fair value option) 26.00%qcom_EffectiveOwnershipInterestInDebtMutualFundFairValueOption    
Other than Temporary Impairment, Credit Losses Recognized in Earnings, Credit Losses on Debt Securities Held 0us-gaap_OtherThanTemporaryImpairmentCreditLossesRecognizedInEarningsCreditLossesOnDebtSecuritiesHeld   0us-gaap_OtherThanTemporaryImpairmentCreditLossesRecognizedInEarningsCreditLossesOnDebtSecuritiesHeld
U.S. Treasury securities and government-related securities [Member]      
Schedule of Marketable Securities [Line Items]      
Restricted Marketable Securities 146,000,000qcom_RestrictedMarketableSecurities
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_USTreasuryAndGovernmentMember
   
Trading Securities [Abstract]      
Trading - Current 314,000,000us-gaap_TradingSecurities
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_USTreasuryAndGovernmentMember
  320,000,000us-gaap_TradingSecurities
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_USTreasuryAndGovernmentMember
Trading - Noncurrent 30,000,000qcom_TradingSecuritiesNoncurrent
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_USTreasuryAndGovernmentMember
  38,000,000qcom_TradingSecuritiesNoncurrent
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_USTreasuryAndGovernmentMember
Available-for-sale Securities [Abstract]      
Available-for-sale - Current 500,000,000us-gaap_AvailableForSaleSecuritiesCurrent
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_USTreasuryAndGovernmentMember
  805,000,000us-gaap_AvailableForSaleSecuritiesCurrent
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_USTreasuryAndGovernmentMember
Available-for-sale - Noncurrent 660,000,000us-gaap_AvailableForSaleSecuritiesNoncurrent
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_USTreasuryAndGovernmentMember
  392,000,000us-gaap_AvailableForSaleSecuritiesNoncurrent
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_USTreasuryAndGovernmentMember
Corporate bonds and notes      
Schedule of Marketable Securities [Line Items]      
Restricted Marketable Securities 2,800,000,000qcom_RestrictedMarketableSecurities
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_CorporateDebtSecuritiesMember
   
Trading Securities [Abstract]      
Trading - Current 195,000,000us-gaap_TradingSecurities
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_CorporateDebtSecuritiesMember
  191,000,000us-gaap_TradingSecurities
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_CorporateDebtSecuritiesMember
Trading - Noncurrent 367,000,000qcom_TradingSecuritiesNoncurrent
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_CorporateDebtSecuritiesMember
  367,000,000qcom_TradingSecuritiesNoncurrent
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_CorporateDebtSecuritiesMember
Available-for-sale Securities [Abstract]      
Available-for-sale - Current 7,612,000,000us-gaap_AvailableForSaleSecuritiesCurrent
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_CorporateDebtSecuritiesMember
  6,274,000,000us-gaap_AvailableForSaleSecuritiesCurrent
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_CorporateDebtSecuritiesMember
Available-for-sale - Noncurrent 7,420,000,000us-gaap_AvailableForSaleSecuritiesNoncurrent
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_CorporateDebtSecuritiesMember
  7,649,000,000us-gaap_AvailableForSaleSecuritiesNoncurrent
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_CorporateDebtSecuritiesMember
Mortgage- and asset-backed securities      
Schedule of Marketable Securities [Line Items]      
Restricted Marketable Securities 777,000,000qcom_RestrictedMarketableSecurities
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_AssetBackedSecuritiesMember
   
Trading Securities [Abstract]      
Trading - Current 0us-gaap_TradingSecurities
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_AssetBackedSecuritiesMember
  0us-gaap_TradingSecurities
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_AssetBackedSecuritiesMember
Trading - Noncurrent 224,000,000qcom_TradingSecuritiesNoncurrent
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_AssetBackedSecuritiesMember
  237,000,000qcom_TradingSecuritiesNoncurrent
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_AssetBackedSecuritiesMember
Available-for-sale Securities [Abstract]      
Available-for-sale - Current 1,111,000,000us-gaap_AvailableForSaleSecuritiesCurrent
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_AssetBackedSecuritiesMember
  1,063,000,000us-gaap_AvailableForSaleSecuritiesCurrent
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_AssetBackedSecuritiesMember
Available-for-sale - Noncurrent 201,000,000us-gaap_AvailableForSaleSecuritiesNoncurrent
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_AssetBackedSecuritiesMember
  195,000,000us-gaap_AvailableForSaleSecuritiesNoncurrent
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_AssetBackedSecuritiesMember
Auction rate securities      
Available-for-sale Securities [Abstract]      
Available-for-sale - Current 0us-gaap_AvailableForSaleSecuritiesCurrent
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_AuctionRateSecuritiesMember
  0us-gaap_AvailableForSaleSecuritiesCurrent
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_AuctionRateSecuritiesMember
Available-for-sale - Noncurrent 47,000,000us-gaap_AvailableForSaleSecuritiesNoncurrent
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_AuctionRateSecuritiesMember
  83,000,000us-gaap_AvailableForSaleSecuritiesNoncurrent
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_AuctionRateSecuritiesMember
Common and preferred stock      
Available-for-sale Securities [Abstract]      
Available-for-sale - Current 1,008,000,000us-gaap_AvailableForSaleSecuritiesCurrent
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= qcom_CommonAndPreferredStockMember
  192,000,000us-gaap_AvailableForSaleSecuritiesCurrent
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= qcom_CommonAndPreferredStockMember
Available-for-sale - Noncurrent 805,000,000us-gaap_AvailableForSaleSecuritiesNoncurrent
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= qcom_CommonAndPreferredStockMember
  1,605,000,000us-gaap_AvailableForSaleSecuritiesNoncurrent
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= qcom_CommonAndPreferredStockMember
Equity funds      
Available-for-sale Securities [Abstract]      
Available-for-sale - Current 0us-gaap_AvailableForSaleSecuritiesCurrent
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_EquityFundsMember
  0us-gaap_AvailableForSaleSecuritiesCurrent
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_EquityFundsMember
Available-for-sale - Noncurrent 763,000,000us-gaap_AvailableForSaleSecuritiesNoncurrent
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_EquityFundsMember
  541,000,000us-gaap_AvailableForSaleSecuritiesNoncurrent
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_EquityFundsMember
Debt funds      
Available-for-sale Securities [Abstract]      
Available-for-sale - Current 723,000,000us-gaap_AvailableForSaleSecuritiesCurrent
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_OtherDebtSecuritiesMember
  813,000,000us-gaap_AvailableForSaleSecuritiesCurrent
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_OtherDebtSecuritiesMember
Available-for-sale - Noncurrent 2,514,000,000us-gaap_AvailableForSaleSecuritiesNoncurrent
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_OtherDebtSecuritiesMember
  2,560,000,000us-gaap_AvailableForSaleSecuritiesNoncurrent
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_OtherDebtSecuritiesMember
Fair Value Option [Abstract]      
Fair value option - Current 0us-gaap_OtherMarketableSecuritiesCurrent
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_OtherDebtSecuritiesMember
  0us-gaap_OtherMarketableSecuritiesCurrent
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_OtherDebtSecuritiesMember
Fair value option - Noncurrent 784,000,000us-gaap_OtherMarketableSecuritiesNoncurrent
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_OtherDebtSecuritiesMember
  790,000,000us-gaap_OtherMarketableSecuritiesNoncurrent
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_OtherDebtSecuritiesMember
(Decrease) increase in fair value recognized in investment income (6,000,000)us-gaap_FairValueOptionChangesInFairValueGainLoss1
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_OtherDebtSecuritiesMember
13,000,000us-gaap_FairValueOptionChangesInFairValueGainLoss1
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_OtherDebtSecuritiesMember
 
United Kingdom, Pounds      
Schedule of Marketable Securities [Line Items]      
Threshold To Set Aside Marketable Securities 1,900,000,000qcom_ThresholdToSetAsideMarketableSecurities
/ us-gaap_CurrencyAxis
= currency_GBP
   
United States of America, Dollars      
Schedule of Marketable Securities [Line Items]      
Threshold To Set Aside Marketable Securities $ 2,800,000,000qcom_ThresholdToSetAsideMarketableSecurities
/ us-gaap_CurrencyAxis
= currency_USD