Quarterly report pursuant to Section 13 or 15(d)

Marketable Securities (Details)

v2.4.1.9
Marketable Securities (Details) (USD $)
3 Months Ended 6 Months Ended
Mar. 29, 2015
Mar. 30, 2014
Mar. 30, 2014
Sep. 28, 2014
Apr. 21, 2015
Schedule of Marketable Securities [Line Items]          
Restricted Cash and Cash Equivalents, Current $ 24,000,000us-gaap_RestrictedCashAndCashEquivalentsAtCarryingValue        
Total marketable securities - Current 10,063,000,000us-gaap_MarketableSecuritiesCurrent     9,658,000,000us-gaap_MarketableSecuritiesCurrent  
Total marketable securities - Noncurrent 14,055,000,000us-gaap_MarketableSecuritiesNoncurrent     14,457,000,000us-gaap_MarketableSecuritiesNoncurrent  
Trading Securities [Abstract]          
Trading - Current 515,000,000us-gaap_TradingSecurities     511,000,000us-gaap_TradingSecurities  
Trading - Noncurrent 608,000,000qcom_TradingSecuritiesNoncurrent     642,000,000qcom_TradingSecuritiesNoncurrent  
Available-for-sale Securities [Abstract]          
Available-for-sale - Current 9,548,000,000us-gaap_AvailableForSaleSecuritiesCurrent     9,147,000,000us-gaap_AvailableForSaleSecuritiesCurrent  
Available-for-sale - Noncurrent 12,659,000,000us-gaap_AvailableForSaleSecuritiesNoncurrent     13,025,000,000us-gaap_AvailableForSaleSecuritiesNoncurrent  
Fair Value Option [Abstract]          
Effective ownership interest in debt fund (fair value option) 27.00%qcom_EffectiveOwnershipInterestInDebtMutualFundFairValueOption        
(Decrease) increase in fair value recognized in investment income   12,000,000us-gaap_FairValueOptionChangesInFairValueGainLoss1 18,000,000us-gaap_FairValueOptionChangesInFairValueGainLoss1    
Net gains recognized on debt securities classified as trading held at the end of the period 14,000,000us-gaap_TradingSecuritiesUnrealizedHoldingGainLoss        
U.S. Treasury securities and government-related securities [Member]          
Schedule of Marketable Securities [Line Items]          
Restricted Marketable Securities 140,000,000qcom_RestrictedMarketableSecurities
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_USTreasuryAndGovernmentMember
       
Trading Securities [Abstract]          
Trading - Current 338,000,000us-gaap_TradingSecurities
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_USTreasuryAndGovernmentMember
    320,000,000us-gaap_TradingSecurities
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_USTreasuryAndGovernmentMember
 
Trading - Noncurrent 23,000,000qcom_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 385,000,000us-gaap_AvailableForSaleSecuritiesCurrent
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_USTreasuryAndGovernmentMember
    805,000,000us-gaap_AvailableForSaleSecuritiesCurrent
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_USTreasuryAndGovernmentMember
 
Available-for-sale - Noncurrent 715,000,000us-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 2,900,000,000qcom_RestrictedMarketableSecurities
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_CorporateDebtSecuritiesMember
       
Trading Securities [Abstract]          
Trading - Current 177,000,000us-gaap_TradingSecurities
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_CorporateDebtSecuritiesMember
    191,000,000us-gaap_TradingSecurities
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_CorporateDebtSecuritiesMember
 
Trading - Noncurrent 345,000,000qcom_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 7,250,000,000us-gaap_AvailableForSaleSecuritiesCurrent
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_CorporateDebtSecuritiesMember
    6,274,000,000us-gaap_AvailableForSaleSecuritiesCurrent
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_CorporateDebtSecuritiesMember
 
Available-for-sale - Noncurrent 7,668,000,000us-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 [Member]          
Schedule of Marketable Securities [Line Items]          
Restricted Marketable Securities 717,000,000qcom_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 240,000,000qcom_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 1,091,000,000us-gaap_AvailableForSaleSecuritiesCurrent
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_AssetBackedSecuritiesMember
    1,063,000,000us-gaap_AvailableForSaleSecuritiesCurrent
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_AssetBackedSecuritiesMember
 
Available-for-sale - Noncurrent 205,000,000us-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 572,000,000us-gaap_AvailableForSaleSecuritiesCurrent
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= qcom_CommonAndPreferredStockMember
    192,000,000us-gaap_AvailableForSaleSecuritiesCurrent
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= qcom_CommonAndPreferredStockMember
 
Available-for-sale - Noncurrent 819,000,000us-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 646,000,000us-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 250,000,000us-gaap_AvailableForSaleSecuritiesCurrent
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_OtherDebtSecuritiesMember
    813,000,000us-gaap_AvailableForSaleSecuritiesCurrent
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_OtherDebtSecuritiesMember
 
Available-for-sale - Noncurrent 2,559,000,000us-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 788,000,000us-gaap_OtherMarketableSecuritiesNoncurrent
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_OtherDebtSecuritiesMember
    790,000,000us-gaap_OtherMarketableSecuritiesNoncurrent
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_OtherDebtSecuritiesMember
 
Subsequent Event [Member]          
Schedule of Marketable Securities [Line Items]          
Foreign Currency Exchange Rate, Remeasurement         1.4929us-gaap_ForeignCurrencyExchangeRateRemeasurement1
/ us-gaap_SubsequentEventTypeAxis
= us-gaap_SubsequentEventMember
Subsequent Event [Member] | 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
/ us-gaap_SubsequentEventTypeAxis
= us-gaap_SubsequentEventMember
Subsequent Event [Member] | 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
/ us-gaap_SubsequentEventTypeAxis
= us-gaap_SubsequentEventMember