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Investments, Investments Portfolio and AFS Continuous Unrealized Loss Position (Details) (USD $)
In Millions, unless otherwise specified
3 Months Ended 9 Months Ended
Jan. 23, 2015
Jan. 24, 2014
Jan. 23, 2015
Jan. 24, 2014
Apr. 25, 2014
Trading securities:          
Aggregate carrying amount of investments in equity and other securities that are accounted for using the cost or equity method $ 458mdt_CostAndEquityMethodInvestmentWithoutQuotedMarketPrice   $ 458mdt_CostAndEquityMethodInvestmentWithoutQuotedMarketPrice   $ 666mdt_CostAndEquityMethodInvestmentWithoutQuotedMarketPrice
Cost method, equity method, and other investments:          
Short-term and long-term investments, cost 14,554us-gaap_InvestmentOwnedAtCost   14,554us-gaap_InvestmentOwnedAtCost   13,659us-gaap_InvestmentOwnedAtCost
Short-term and long-term investments, unrealized gains 178us-gaap_InvestmentOwnedUnrecognizedUnrealizedAppreciation   178us-gaap_InvestmentOwnedUnrecognizedUnrealizedAppreciation   108us-gaap_InvestmentOwnedUnrecognizedUnrealizedAppreciation
Short-term and long-term investments, unrealized losses (200)us-gaap_InvestmentOwnedUnrecognizedUnrealizedDepreciation   (200)us-gaap_InvestmentOwnedUnrecognizedUnrealizedDepreciation   (108)us-gaap_InvestmentOwnedUnrecognizedUnrealizedDepreciation
Short-term and long-term investments, fair value 14,074us-gaap_Investments   14,074us-gaap_Investments   12,993us-gaap_Investments
AFS Continuous Unrealized Loss Position          
Less than 12 months, fair value 5,540us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThanTwelveMonthsFairValue   5,540us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThanTwelveMonthsFairValue   5,032us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThanTwelveMonthsFairValue
Available-For-Sale Securities, Continuous Unrealized Loss Position, Less Than 12 Months, Accumulated Loss (180)us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss   (180)us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss   (90)us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss
More than 12 months, fair value 853us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionTwelveMonthsOrLongerFairValue   853us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionTwelveMonthsOrLongerFairValue   221us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionTwelveMonthsOrLongerFairValue
Available-For-Sale Securities, Continuous Unrealized Loss Position, 12 Months Or Longer, Accumulated Loss (20)us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss   (20)us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss   (18)us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss
Available for Sale Securities          
Available-for-sale securities:          
Available-for-sale securities, cost 40us-gaap_AvailableForSaleSecuritiesAmortizedCost
/ us-gaap_InvestmentTypeAxis
= us-gaap_AvailableforsaleSecuritiesMember
  40us-gaap_AvailableForSaleSecuritiesAmortizedCost
/ us-gaap_InvestmentTypeAxis
= us-gaap_AvailableforsaleSecuritiesMember
  47us-gaap_AvailableForSaleSecuritiesAmortizedCost
/ us-gaap_InvestmentTypeAxis
= us-gaap_AvailableforsaleSecuritiesMember
Available-For-Sale Securities, Accumulated Gross Unrealized Gain, Before Tax 24us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedGainBeforeTax
/ us-gaap_InvestmentTypeAxis
= us-gaap_AvailableforsaleSecuritiesMember
  24us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedGainBeforeTax
/ us-gaap_InvestmentTypeAxis
= us-gaap_AvailableforsaleSecuritiesMember
  15us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedGainBeforeTax
/ us-gaap_InvestmentTypeAxis
= us-gaap_AvailableforsaleSecuritiesMember
Available-For-Sale Securities, Accumulated Gross Unrealized Loss, Before Tax (14)us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedLossBeforeTax
/ us-gaap_InvestmentTypeAxis
= us-gaap_AvailableforsaleSecuritiesMember
  (14)us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedLossBeforeTax
/ us-gaap_InvestmentTypeAxis
= us-gaap_AvailableforsaleSecuritiesMember
  (13)us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedLossBeforeTax
/ us-gaap_InvestmentTypeAxis
= us-gaap_AvailableforsaleSecuritiesMember
Available-for-sale securities, fair value 50us-gaap_AvailableForSaleSecurities
/ us-gaap_InvestmentTypeAxis
= us-gaap_AvailableforsaleSecuritiesMember
  50us-gaap_AvailableForSaleSecurities
/ us-gaap_InvestmentTypeAxis
= us-gaap_AvailableforsaleSecuritiesMember
  49us-gaap_AvailableForSaleSecurities
/ us-gaap_InvestmentTypeAxis
= us-gaap_AvailableforsaleSecuritiesMember
AFS Continuous Unrealized Loss Position          
Less than 12 months, fair value 9us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThanTwelveMonthsFairValue
/ us-gaap_InvestmentTypeAxis
= us-gaap_AvailableforsaleSecuritiesMember
  9us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThanTwelveMonthsFairValue
/ us-gaap_InvestmentTypeAxis
= us-gaap_AvailableforsaleSecuritiesMember
  25us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThanTwelveMonthsFairValue
/ us-gaap_InvestmentTypeAxis
= us-gaap_AvailableforsaleSecuritiesMember
Available-For-Sale Securities, Continuous Unrealized Loss Position, Less Than 12 Months, Accumulated Loss (14)us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss
/ us-gaap_InvestmentTypeAxis
= us-gaap_AvailableforsaleSecuritiesMember
  (14)us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss
/ us-gaap_InvestmentTypeAxis
= us-gaap_AvailableforsaleSecuritiesMember
  (13)us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss
/ us-gaap_InvestmentTypeAxis
= us-gaap_AvailableforsaleSecuritiesMember
More than 12 months, fair value 0us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionTwelveMonthsOrLongerFairValue
/ us-gaap_InvestmentTypeAxis
= us-gaap_AvailableforsaleSecuritiesMember
  0us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionTwelveMonthsOrLongerFairValue
/ us-gaap_InvestmentTypeAxis
= us-gaap_AvailableforsaleSecuritiesMember
  0us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionTwelveMonthsOrLongerFairValue
/ us-gaap_InvestmentTypeAxis
= us-gaap_AvailableforsaleSecuritiesMember
Available-For-Sale Securities, Continuous Unrealized Loss Position, 12 Months Or Longer, Accumulated Loss 0us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss
/ us-gaap_InvestmentTypeAxis
= us-gaap_AvailableforsaleSecuritiesMember
  0us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss
/ us-gaap_InvestmentTypeAxis
= us-gaap_AvailableforsaleSecuritiesMember
  0us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss
/ us-gaap_InvestmentTypeAxis
= us-gaap_AvailableforsaleSecuritiesMember
Corporate Debt Securities          
Available-for-sale securities:          
Available-for-sale securities, cost 5,880us-gaap_AvailableForSaleSecuritiesAmortizedCost
/ us-gaap_InvestmentTypeAxis
= us-gaap_CorporateDebtSecuritiesMember
  5,880us-gaap_AvailableForSaleSecuritiesAmortizedCost
/ us-gaap_InvestmentTypeAxis
= us-gaap_CorporateDebtSecuritiesMember
  5,504us-gaap_AvailableForSaleSecuritiesAmortizedCost
/ us-gaap_InvestmentTypeAxis
= us-gaap_CorporateDebtSecuritiesMember
Available-For-Sale Securities, Accumulated Gross Unrealized Gain, Before Tax 88us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedGainBeforeTax
/ us-gaap_InvestmentTypeAxis
= us-gaap_CorporateDebtSecuritiesMember
  88us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedGainBeforeTax
/ us-gaap_InvestmentTypeAxis
= us-gaap_CorporateDebtSecuritiesMember
  55us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedGainBeforeTax
/ us-gaap_InvestmentTypeAxis
= us-gaap_CorporateDebtSecuritiesMember
Available-For-Sale Securities, Accumulated Gross Unrealized Loss, Before Tax (20)us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedLossBeforeTax
/ us-gaap_InvestmentTypeAxis
= us-gaap_CorporateDebtSecuritiesMember
  (20)us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedLossBeforeTax
/ us-gaap_InvestmentTypeAxis
= us-gaap_CorporateDebtSecuritiesMember
  (17)us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedLossBeforeTax
/ us-gaap_InvestmentTypeAxis
= us-gaap_CorporateDebtSecuritiesMember
Available-for-sale securities, fair value 5,948us-gaap_AvailableForSaleSecurities
/ us-gaap_InvestmentTypeAxis
= us-gaap_CorporateDebtSecuritiesMember
  5,948us-gaap_AvailableForSaleSecurities
/ us-gaap_InvestmentTypeAxis
= us-gaap_CorporateDebtSecuritiesMember
  5,542us-gaap_AvailableForSaleSecurities
/ us-gaap_InvestmentTypeAxis
= us-gaap_CorporateDebtSecuritiesMember
AFS Continuous Unrealized Loss Position          
Less than 12 months, fair value 2,026us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThanTwelveMonthsFairValue
/ us-gaap_InvestmentTypeAxis
= us-gaap_CorporateDebtSecuritiesMember
  2,026us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThanTwelveMonthsFairValue
/ us-gaap_InvestmentTypeAxis
= us-gaap_CorporateDebtSecuritiesMember
  1,601us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThanTwelveMonthsFairValue
/ us-gaap_InvestmentTypeAxis
= us-gaap_CorporateDebtSecuritiesMember
Available-For-Sale Securities, Continuous Unrealized Loss Position, Less Than 12 Months, Accumulated Loss (18)us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss
/ us-gaap_InvestmentTypeAxis
= us-gaap_CorporateDebtSecuritiesMember
  (18)us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss
/ us-gaap_InvestmentTypeAxis
= us-gaap_CorporateDebtSecuritiesMember
  (14)us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss
/ us-gaap_InvestmentTypeAxis
= us-gaap_CorporateDebtSecuritiesMember
More than 12 months, fair value 34us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionTwelveMonthsOrLongerFairValue
/ us-gaap_InvestmentTypeAxis
= us-gaap_CorporateDebtSecuritiesMember
  34us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionTwelveMonthsOrLongerFairValue
/ us-gaap_InvestmentTypeAxis
= us-gaap_CorporateDebtSecuritiesMember
  50us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionTwelveMonthsOrLongerFairValue
/ us-gaap_InvestmentTypeAxis
= us-gaap_CorporateDebtSecuritiesMember
Available-For-Sale Securities, Continuous Unrealized Loss Position, 12 Months Or Longer, Accumulated Loss (2)us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss
/ us-gaap_InvestmentTypeAxis
= us-gaap_CorporateDebtSecuritiesMember
  (2)us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss
/ us-gaap_InvestmentTypeAxis
= us-gaap_CorporateDebtSecuritiesMember
  (3)us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss
/ us-gaap_InvestmentTypeAxis
= us-gaap_CorporateDebtSecuritiesMember
Auction Rate Securities          
Available-for-sale securities:          
Available-for-sale securities, cost 109us-gaap_AvailableForSaleSecuritiesAmortizedCost
/ us-gaap_InvestmentTypeAxis
= us-gaap_AuctionRateSecuritiesMember
  109us-gaap_AvailableForSaleSecuritiesAmortizedCost
/ us-gaap_InvestmentTypeAxis
= us-gaap_AuctionRateSecuritiesMember
  109us-gaap_AvailableForSaleSecuritiesAmortizedCost
/ us-gaap_InvestmentTypeAxis
= us-gaap_AuctionRateSecuritiesMember
Available-For-Sale Securities, Accumulated Gross Unrealized Gain, Before Tax 0us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedGainBeforeTax
/ us-gaap_InvestmentTypeAxis
= us-gaap_AuctionRateSecuritiesMember
  0us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedGainBeforeTax
/ us-gaap_InvestmentTypeAxis
= us-gaap_AuctionRateSecuritiesMember
  0us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedGainBeforeTax
/ us-gaap_InvestmentTypeAxis
= us-gaap_AuctionRateSecuritiesMember
Available-For-Sale Securities, Accumulated Gross Unrealized Loss, Before Tax (10)us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedLossBeforeTax
/ us-gaap_InvestmentTypeAxis
= us-gaap_AuctionRateSecuritiesMember
  (10)us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedLossBeforeTax
/ us-gaap_InvestmentTypeAxis
= us-gaap_AuctionRateSecuritiesMember
  (12)us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedLossBeforeTax
/ us-gaap_InvestmentTypeAxis
= us-gaap_AuctionRateSecuritiesMember
Available-for-sale securities, fair value 99us-gaap_AvailableForSaleSecurities
/ us-gaap_InvestmentTypeAxis
= us-gaap_AuctionRateSecuritiesMember
  99us-gaap_AvailableForSaleSecurities
/ us-gaap_InvestmentTypeAxis
= us-gaap_AuctionRateSecuritiesMember
  97us-gaap_AvailableForSaleSecurities
/ us-gaap_InvestmentTypeAxis
= us-gaap_AuctionRateSecuritiesMember
AFS Continuous Unrealized Loss Position          
Less than 12 months, fair value 0us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThanTwelveMonthsFairValue
/ us-gaap_InvestmentTypeAxis
= us-gaap_AuctionRateSecuritiesMember
  0us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThanTwelveMonthsFairValue
/ us-gaap_InvestmentTypeAxis
= us-gaap_AuctionRateSecuritiesMember
  0us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThanTwelveMonthsFairValue
/ us-gaap_InvestmentTypeAxis
= us-gaap_AuctionRateSecuritiesMember
Available-For-Sale Securities, Continuous Unrealized Loss Position, Less Than 12 Months, Accumulated Loss 0us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss
/ us-gaap_InvestmentTypeAxis
= us-gaap_AuctionRateSecuritiesMember
  0us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss
/ us-gaap_InvestmentTypeAxis
= us-gaap_AuctionRateSecuritiesMember
  0us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss
/ us-gaap_InvestmentTypeAxis
= us-gaap_AuctionRateSecuritiesMember
More than 12 months, fair value 99us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionTwelveMonthsOrLongerFairValue
/ us-gaap_InvestmentTypeAxis
= us-gaap_AuctionRateSecuritiesMember
  99us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionTwelveMonthsOrLongerFairValue
/ us-gaap_InvestmentTypeAxis
= us-gaap_AuctionRateSecuritiesMember
  97us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionTwelveMonthsOrLongerFairValue
/ us-gaap_InvestmentTypeAxis
= us-gaap_AuctionRateSecuritiesMember
Available-For-Sale Securities, Continuous Unrealized Loss Position, 12 Months Or Longer, Accumulated Loss (10)us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss
/ us-gaap_InvestmentTypeAxis
= us-gaap_AuctionRateSecuritiesMember
  (10)us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss
/ us-gaap_InvestmentTypeAxis
= us-gaap_AuctionRateSecuritiesMember
  (12)us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss
/ us-gaap_InvestmentTypeAxis
= us-gaap_AuctionRateSecuritiesMember
Mortgage Backed Securities          
Available-for-sale securities:          
Available-for-sale securities, cost 1,360us-gaap_AvailableForSaleSecuritiesAmortizedCost
/ us-gaap_InvestmentTypeAxis
= us-gaap_MortgageBackedSecuritiesMember
  1,360us-gaap_AvailableForSaleSecuritiesAmortizedCost
/ us-gaap_InvestmentTypeAxis
= us-gaap_MortgageBackedSecuritiesMember
  1,337us-gaap_AvailableForSaleSecuritiesAmortizedCost
/ us-gaap_InvestmentTypeAxis
= us-gaap_MortgageBackedSecuritiesMember
Available-For-Sale Securities, Accumulated Gross Unrealized Gain, Before Tax 20us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedGainBeforeTax
/ us-gaap_InvestmentTypeAxis
= us-gaap_MortgageBackedSecuritiesMember
  20us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedGainBeforeTax
/ us-gaap_InvestmentTypeAxis
= us-gaap_MortgageBackedSecuritiesMember
  7us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedGainBeforeTax
/ us-gaap_InvestmentTypeAxis
= us-gaap_MortgageBackedSecuritiesMember
Available-For-Sale Securities, Accumulated Gross Unrealized Loss, Before Tax (5)us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedLossBeforeTax
/ us-gaap_InvestmentTypeAxis
= us-gaap_MortgageBackedSecuritiesMember
  (5)us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedLossBeforeTax
/ us-gaap_InvestmentTypeAxis
= us-gaap_MortgageBackedSecuritiesMember
  (8)us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedLossBeforeTax
/ us-gaap_InvestmentTypeAxis
= us-gaap_MortgageBackedSecuritiesMember
Available-for-sale securities, fair value 1,375us-gaap_AvailableForSaleSecurities
/ us-gaap_InvestmentTypeAxis
= us-gaap_MortgageBackedSecuritiesMember
  1,375us-gaap_AvailableForSaleSecurities
/ us-gaap_InvestmentTypeAxis
= us-gaap_MortgageBackedSecuritiesMember
  1,336us-gaap_AvailableForSaleSecurities
/ us-gaap_InvestmentTypeAxis
= us-gaap_MortgageBackedSecuritiesMember
AFS Continuous Unrealized Loss Position          
Less than 12 months, fair value 308us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThanTwelveMonthsFairValue
/ us-gaap_InvestmentTypeAxis
= us-gaap_MortgageBackedSecuritiesMember
  308us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThanTwelveMonthsFairValue
/ us-gaap_InvestmentTypeAxis
= us-gaap_MortgageBackedSecuritiesMember
  682us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThanTwelveMonthsFairValue
/ us-gaap_InvestmentTypeAxis
= us-gaap_MortgageBackedSecuritiesMember
Available-For-Sale Securities, Continuous Unrealized Loss Position, Less Than 12 Months, Accumulated Loss (2)us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss
/ us-gaap_InvestmentTypeAxis
= us-gaap_MortgageBackedSecuritiesMember
  (2)us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss
/ us-gaap_InvestmentTypeAxis
= us-gaap_MortgageBackedSecuritiesMember
  (7)us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss
/ us-gaap_InvestmentTypeAxis
= us-gaap_MortgageBackedSecuritiesMember
More than 12 months, fair value 234us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionTwelveMonthsOrLongerFairValue
/ us-gaap_InvestmentTypeAxis
= us-gaap_MortgageBackedSecuritiesMember
  234us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionTwelveMonthsOrLongerFairValue
/ us-gaap_InvestmentTypeAxis
= us-gaap_MortgageBackedSecuritiesMember
  28us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionTwelveMonthsOrLongerFairValue
/ us-gaap_InvestmentTypeAxis
= us-gaap_MortgageBackedSecuritiesMember
Available-For-Sale Securities, Continuous Unrealized Loss Position, 12 Months Or Longer, Accumulated Loss (3)us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss
/ us-gaap_InvestmentTypeAxis
= us-gaap_MortgageBackedSecuritiesMember
  (3)us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss
/ us-gaap_InvestmentTypeAxis
= us-gaap_MortgageBackedSecuritiesMember
  (1)us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss
/ us-gaap_InvestmentTypeAxis
= us-gaap_MortgageBackedSecuritiesMember
US Government and Agency Securities          
Available-for-sale securities:          
Available-for-sale securities, cost 3,077us-gaap_AvailableForSaleSecuritiesAmortizedCost
/ us-gaap_InvestmentTypeAxis
= us-gaap_USGovernmentAgenciesDebtSecuritiesMember
  3,077us-gaap_AvailableForSaleSecuritiesAmortizedCost
/ us-gaap_InvestmentTypeAxis
= us-gaap_USGovernmentAgenciesDebtSecuritiesMember
  3,138us-gaap_AvailableForSaleSecuritiesAmortizedCost
/ us-gaap_InvestmentTypeAxis
= us-gaap_USGovernmentAgenciesDebtSecuritiesMember
Available-For-Sale Securities, Accumulated Gross Unrealized Gain, Before Tax 22us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedGainBeforeTax
/ us-gaap_InvestmentTypeAxis
= us-gaap_USGovernmentAgenciesDebtSecuritiesMember
  22us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedGainBeforeTax
/ us-gaap_InvestmentTypeAxis
= us-gaap_USGovernmentAgenciesDebtSecuritiesMember
  7us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedGainBeforeTax
/ us-gaap_InvestmentTypeAxis
= us-gaap_USGovernmentAgenciesDebtSecuritiesMember
Available-For-Sale Securities, Accumulated Gross Unrealized Loss, Before Tax (7)us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedLossBeforeTax
/ us-gaap_InvestmentTypeAxis
= us-gaap_USGovernmentAgenciesDebtSecuritiesMember
  (7)us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedLossBeforeTax
/ us-gaap_InvestmentTypeAxis
= us-gaap_USGovernmentAgenciesDebtSecuritiesMember
  (29)us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedLossBeforeTax
/ us-gaap_InvestmentTypeAxis
= us-gaap_USGovernmentAgenciesDebtSecuritiesMember
Available-for-sale securities, fair value 3,092us-gaap_AvailableForSaleSecurities
/ us-gaap_InvestmentTypeAxis
= us-gaap_USGovernmentAgenciesDebtSecuritiesMember
  3,092us-gaap_AvailableForSaleSecurities
/ us-gaap_InvestmentTypeAxis
= us-gaap_USGovernmentAgenciesDebtSecuritiesMember
  3,116us-gaap_AvailableForSaleSecurities
/ us-gaap_InvestmentTypeAxis
= us-gaap_USGovernmentAgenciesDebtSecuritiesMember
AFS Continuous Unrealized Loss Position          
Less than 12 months, fair value 381us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThanTwelveMonthsFairValue
/ us-gaap_InvestmentTypeAxis
= us-gaap_USGovernmentAgenciesDebtSecuritiesMember
  381us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThanTwelveMonthsFairValue
/ us-gaap_InvestmentTypeAxis
= us-gaap_USGovernmentAgenciesDebtSecuritiesMember
  1,500us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThanTwelveMonthsFairValue
/ us-gaap_InvestmentTypeAxis
= us-gaap_USGovernmentAgenciesDebtSecuritiesMember
Available-For-Sale Securities, Continuous Unrealized Loss Position, Less Than 12 Months, Accumulated Loss (2)us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss
/ us-gaap_InvestmentTypeAxis
= us-gaap_USGovernmentAgenciesDebtSecuritiesMember
  (2)us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss
/ us-gaap_InvestmentTypeAxis
= us-gaap_USGovernmentAgenciesDebtSecuritiesMember
  (27)us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss
/ us-gaap_InvestmentTypeAxis
= us-gaap_USGovernmentAgenciesDebtSecuritiesMember
More than 12 months, fair value 486us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionTwelveMonthsOrLongerFairValue
/ us-gaap_InvestmentTypeAxis
= us-gaap_USGovernmentAgenciesDebtSecuritiesMember
  486us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionTwelveMonthsOrLongerFairValue
/ us-gaap_InvestmentTypeAxis
= us-gaap_USGovernmentAgenciesDebtSecuritiesMember
  46us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionTwelveMonthsOrLongerFairValue
/ us-gaap_InvestmentTypeAxis
= us-gaap_USGovernmentAgenciesDebtSecuritiesMember
Available-For-Sale Securities, Continuous Unrealized Loss Position, 12 Months Or Longer, Accumulated Loss (5)us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss
/ us-gaap_InvestmentTypeAxis
= us-gaap_USGovernmentAgenciesDebtSecuritiesMember
  (5)us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss
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  (2)us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss
/ us-gaap_InvestmentTypeAxis
= us-gaap_USGovernmentAgenciesDebtSecuritiesMember
Foreign Government and Agency Securities          
Available-for-sale securities:          
Available-for-sale securities, cost 79us-gaap_AvailableForSaleSecuritiesAmortizedCost
/ us-gaap_InvestmentTypeAxis
= us-gaap_ForeignGovernmentDebtSecuritiesMember
  79us-gaap_AvailableForSaleSecuritiesAmortizedCost
/ us-gaap_InvestmentTypeAxis
= us-gaap_ForeignGovernmentDebtSecuritiesMember
  67us-gaap_AvailableForSaleSecuritiesAmortizedCost
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/ us-gaap_InvestmentTypeAxis
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  67us-gaap_AvailableForSaleSecurities
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= us-gaap_ForeignGovernmentDebtSecuritiesMember
Certificates of Deposit          
Available-for-sale securities:          
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Available-for-sale securities:          
Available-for-sale securities, cost 497us-gaap_AvailableForSaleSecuritiesAmortizedCost
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/ us-gaap_InvestmentTypeAxis
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/ us-gaap_InvestmentTypeAxis
= us-gaap_AssetBackedSecuritiesMember
Available-For-Sale Securities, Accumulated Gross Unrealized Loss, Before Tax 0us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedLossBeforeTax
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/ us-gaap_InvestmentTypeAxis
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/ us-gaap_InvestmentTypeAxis
= us-gaap_AssetBackedSecuritiesMember
Available-for-sale securities, fair value 499us-gaap_AvailableForSaleSecurities
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= us-gaap_AssetBackedSecuritiesMember
  499us-gaap_AvailableForSaleSecurities
/ us-gaap_InvestmentTypeAxis
= us-gaap_AssetBackedSecuritiesMember
  542us-gaap_AvailableForSaleSecurities
/ us-gaap_InvestmentTypeAxis
= us-gaap_AssetBackedSecuritiesMember
Debt Funds [Member]          
Available-for-sale securities:          
Available-for-sale securities, cost 2,954us-gaap_AvailableForSaleSecuritiesAmortizedCost
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= mdt_DebtFundsMember
  2,954us-gaap_AvailableForSaleSecuritiesAmortizedCost
/ us-gaap_InvestmentTypeAxis
= mdt_DebtFundsMember
  2,143us-gaap_AvailableForSaleSecuritiesAmortizedCost
/ us-gaap_InvestmentTypeAxis
= mdt_DebtFundsMember
Available-For-Sale Securities, Accumulated Gross Unrealized Gain, Before Tax 6us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedGainBeforeTax
/ us-gaap_InvestmentTypeAxis
= mdt_DebtFundsMember
  6us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedGainBeforeTax
/ us-gaap_InvestmentTypeAxis
= mdt_DebtFundsMember
  9us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedGainBeforeTax
/ us-gaap_InvestmentTypeAxis
= mdt_DebtFundsMember
Available-For-Sale Securities, Accumulated Gross Unrealized Loss, Before Tax (144)us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedLossBeforeTax
/ us-gaap_InvestmentTypeAxis
= mdt_DebtFundsMember
  (144)us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedLossBeforeTax
/ us-gaap_InvestmentTypeAxis
= mdt_DebtFundsMember
  (29)us-gaap_AvailableForSaleSecuritiesAccumulatedGrossUnrealizedLossBeforeTax
/ us-gaap_InvestmentTypeAxis
= mdt_DebtFundsMember
Available-for-sale securities, fair value 2,816us-gaap_AvailableForSaleSecurities
/ us-gaap_InvestmentTypeAxis
= mdt_DebtFundsMember
  2,816us-gaap_AvailableForSaleSecurities
/ us-gaap_InvestmentTypeAxis
= mdt_DebtFundsMember
  2,123us-gaap_AvailableForSaleSecurities
/ us-gaap_InvestmentTypeAxis
= mdt_DebtFundsMember
AFS Continuous Unrealized Loss Position          
Less than 12 months, fair value 2,816us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThanTwelveMonthsFairValue
/ us-gaap_InvestmentTypeAxis
= mdt_DebtFundsMember
  2,816us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThanTwelveMonthsFairValue
/ us-gaap_InvestmentTypeAxis
= mdt_DebtFundsMember
  1,224us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThanTwelveMonthsFairValue
/ us-gaap_InvestmentTypeAxis
= mdt_DebtFundsMember
Available-For-Sale Securities, Continuous Unrealized Loss Position, Less Than 12 Months, Accumulated Loss (144)us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss
/ us-gaap_InvestmentTypeAxis
= mdt_DebtFundsMember
  (144)us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss
/ us-gaap_InvestmentTypeAxis
= mdt_DebtFundsMember
  (29)us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss
/ us-gaap_InvestmentTypeAxis
= mdt_DebtFundsMember
More than 12 months, fair value 0us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionTwelveMonthsOrLongerFairValue
/ us-gaap_InvestmentTypeAxis
= mdt_DebtFundsMember
  0us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionTwelveMonthsOrLongerFairValue
/ us-gaap_InvestmentTypeAxis
= mdt_DebtFundsMember
  0us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionTwelveMonthsOrLongerFairValue
/ us-gaap_InvestmentTypeAxis
= mdt_DebtFundsMember
Available-For-Sale Securities, Continuous Unrealized Loss Position, 12 Months Or Longer, Accumulated Loss 0us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss
/ us-gaap_InvestmentTypeAxis
= mdt_DebtFundsMember
  0us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss
/ us-gaap_InvestmentTypeAxis
= mdt_DebtFundsMember
  0us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss
/ us-gaap_InvestmentTypeAxis
= mdt_DebtFundsMember
Exchange Traded Funds          
Trading securities:          
Trading securities, cost 58us-gaap_TradingSecuritiesCost
/ us-gaap_InvestmentTypeAxis
= us-gaap_ExchangeTradedFundsMember
  58us-gaap_TradingSecuritiesCost
/ us-gaap_InvestmentTypeAxis
= us-gaap_ExchangeTradedFundsMember
  54us-gaap_TradingSecuritiesCost
/ us-gaap_InvestmentTypeAxis
= us-gaap_ExchangeTradedFundsMember
Trading securities, unrealized gains 16mdt_TradingSecuritiesUnrealizedHoldingGains
/ us-gaap_InvestmentTypeAxis
= us-gaap_ExchangeTradedFundsMember
  16mdt_TradingSecuritiesUnrealizedHoldingGains
/ us-gaap_InvestmentTypeAxis
= us-gaap_ExchangeTradedFundsMember
  13mdt_TradingSecuritiesUnrealizedHoldingGains
/ us-gaap_InvestmentTypeAxis
= us-gaap_ExchangeTradedFundsMember
Trading securities, unrealized losses 0mdt_TradingSecuritiesUnrealizedHoldingLosses
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= us-gaap_ExchangeTradedFundsMember
  0mdt_TradingSecuritiesUnrealizedHoldingLosses
/ us-gaap_InvestmentTypeAxis
= us-gaap_ExchangeTradedFundsMember
  0mdt_TradingSecuritiesUnrealizedHoldingLosses
/ us-gaap_InvestmentTypeAxis
= us-gaap_ExchangeTradedFundsMember
Trading securities, fair value 74us-gaap_TradingSecurities
/ us-gaap_InvestmentTypeAxis
= us-gaap_ExchangeTradedFundsMember
  74us-gaap_TradingSecurities
/ us-gaap_InvestmentTypeAxis
= us-gaap_ExchangeTradedFundsMember
  67us-gaap_TradingSecurities
/ us-gaap_InvestmentTypeAxis
= us-gaap_ExchangeTradedFundsMember
Debt Securities          
AFS Gross Realized Gain (Loss)          
Proceeds from sales 1,478us-gaap_AvailableForSaleSecuritiesGrossRealizedGainsLossesSaleProceeds
/ us-gaap_InvestmentTypeAxis
= us-gaap_DebtSecuritiesMember
1,280us-gaap_AvailableForSaleSecuritiesGrossRealizedGainsLossesSaleProceeds
/ us-gaap_InvestmentTypeAxis
= us-gaap_DebtSecuritiesMember
4,114us-gaap_AvailableForSaleSecuritiesGrossRealizedGainsLossesSaleProceeds
/ us-gaap_InvestmentTypeAxis
= us-gaap_DebtSecuritiesMember
5,515us-gaap_AvailableForSaleSecuritiesGrossRealizedGainsLossesSaleProceeds
/ us-gaap_InvestmentTypeAxis
= us-gaap_DebtSecuritiesMember
 
Gross realized gains 10us-gaap_AvailableForSaleSecuritiesGrossRealizedGains
/ us-gaap_InvestmentTypeAxis
= us-gaap_DebtSecuritiesMember
0us-gaap_AvailableForSaleSecuritiesGrossRealizedGains
/ us-gaap_InvestmentTypeAxis
= us-gaap_DebtSecuritiesMember
26us-gaap_AvailableForSaleSecuritiesGrossRealizedGains
/ us-gaap_InvestmentTypeAxis
= us-gaap_DebtSecuritiesMember
6us-gaap_AvailableForSaleSecuritiesGrossRealizedGains
/ us-gaap_InvestmentTypeAxis
= us-gaap_DebtSecuritiesMember
 
Gross realized losses (4)us-gaap_AvailableForSaleSecuritiesGrossRealizedLosses
/ us-gaap_InvestmentTypeAxis
= us-gaap_DebtSecuritiesMember
(3)us-gaap_AvailableForSaleSecuritiesGrossRealizedLosses
/ us-gaap_InvestmentTypeAxis
= us-gaap_DebtSecuritiesMember
(9)us-gaap_AvailableForSaleSecuritiesGrossRealizedLosses
/ us-gaap_InvestmentTypeAxis
= us-gaap_DebtSecuritiesMember
(9)us-gaap_AvailableForSaleSecuritiesGrossRealizedLosses
/ us-gaap_InvestmentTypeAxis
= us-gaap_DebtSecuritiesMember
 
Impairment losses recognized 0us-gaap_ImpairmentOfInvestments
/ us-gaap_InvestmentTypeAxis
= us-gaap_DebtSecuritiesMember
0us-gaap_ImpairmentOfInvestments
/ us-gaap_InvestmentTypeAxis
= us-gaap_DebtSecuritiesMember
0us-gaap_ImpairmentOfInvestments
/ us-gaap_InvestmentTypeAxis
= us-gaap_DebtSecuritiesMember
0us-gaap_ImpairmentOfInvestments
/ us-gaap_InvestmentTypeAxis
= us-gaap_DebtSecuritiesMember
 
Equity Securities          
AFS Gross Realized Gain (Loss)          
Proceeds from sales 208us-gaap_AvailableForSaleSecuritiesGrossRealizedGainsLossesSaleProceeds
/ us-gaap_InvestmentTypeAxis
= us-gaap_EquitySecuritiesMember
35us-gaap_AvailableForSaleSecuritiesGrossRealizedGainsLossesSaleProceeds
/ us-gaap_InvestmentTypeAxis
= us-gaap_EquitySecuritiesMember
237us-gaap_AvailableForSaleSecuritiesGrossRealizedGainsLossesSaleProceeds
/ us-gaap_InvestmentTypeAxis
= us-gaap_EquitySecuritiesMember
91us-gaap_AvailableForSaleSecuritiesGrossRealizedGainsLossesSaleProceeds
/ us-gaap_InvestmentTypeAxis
= us-gaap_EquitySecuritiesMember
 
Gross realized gains 99us-gaap_AvailableForSaleSecuritiesGrossRealizedGains
/ us-gaap_InvestmentTypeAxis
= us-gaap_EquitySecuritiesMember
26us-gaap_AvailableForSaleSecuritiesGrossRealizedGains
/ us-gaap_InvestmentTypeAxis
= us-gaap_EquitySecuritiesMember
157us-gaap_AvailableForSaleSecuritiesGrossRealizedGains
/ us-gaap_InvestmentTypeAxis
= us-gaap_EquitySecuritiesMember
59us-gaap_AvailableForSaleSecuritiesGrossRealizedGains
/ us-gaap_InvestmentTypeAxis
= us-gaap_EquitySecuritiesMember
 
Gross realized losses 0us-gaap_AvailableForSaleSecuritiesGrossRealizedLosses
/ us-gaap_InvestmentTypeAxis
= us-gaap_EquitySecuritiesMember
0us-gaap_AvailableForSaleSecuritiesGrossRealizedLosses
/ us-gaap_InvestmentTypeAxis
= us-gaap_EquitySecuritiesMember
0us-gaap_AvailableForSaleSecuritiesGrossRealizedLosses
/ us-gaap_InvestmentTypeAxis
= us-gaap_EquitySecuritiesMember
0us-gaap_AvailableForSaleSecuritiesGrossRealizedLosses
/ us-gaap_InvestmentTypeAxis
= us-gaap_EquitySecuritiesMember
 
Impairment losses recognized (1)us-gaap_ImpairmentOfInvestments
/ us-gaap_InvestmentTypeAxis
= us-gaap_EquitySecuritiesMember
0us-gaap_ImpairmentOfInvestments
/ us-gaap_InvestmentTypeAxis
= us-gaap_EquitySecuritiesMember
(22)us-gaap_ImpairmentOfInvestments
/ us-gaap_InvestmentTypeAxis
= us-gaap_EquitySecuritiesMember
0us-gaap_ImpairmentOfInvestments
/ us-gaap_InvestmentTypeAxis
= us-gaap_EquitySecuritiesMember
 
Nonrecurring          
Trading securities:          
Aggregate carrying amount of investments in equity and other securities that are accounted for using the cost or equity method $ 458mdt_CostAndEquityMethodInvestmentWithoutQuotedMarketPrice
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsNonrecurringMember
  $ 458mdt_CostAndEquityMethodInvestmentWithoutQuotedMarketPrice
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsNonrecurringMember
  $ 666mdt_CostAndEquityMethodInvestmentWithoutQuotedMarketPrice
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsNonrecurringMember