Derivatives and Currency Exchange Risk Management - Gains (Losses) on Derivatives and Amounts Reclassified into Income (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Oct. 26, 2018	Oct. 27, 2017	Oct. 26, 2018	Oct. 27, 2017
Derivative Instruments, Gain (Loss) [Line Items]
Currency exchange rate contracts	$ 60	$ (33)	$ 201	$ (122)
Currency exchange rate contracts \| Cash flow hedging
Derivative Instruments, Gain (Loss) [Line Items]
Recognized in AOCI	174	30	444	(220)
Other operating expense, net \| Currency exchange rate contracts
Derivative Instruments, Gain (Loss) [Line Items]
Currency exchange rate contracts	71	(42)	201	(137)
Other operating expense, net \| Currency exchange rate contracts \| Cash flow hedging
Derivative Instruments, Gain (Loss) [Line Items]
Recognized in Income	11	(10)	8	12
Other operating expense, net \| Total return swap
Derivative Instruments, Gain (Loss) [Line Items]
Currency exchange rate contracts	$ (11)	$ 9	$ 0	$ 15

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The effective portion of net gain (loss) reclassified from accumulated other comprehensive income into income on derivative instruments designated and qualifying as hedging instruments.

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Amount of gain (loss) recognized in earnings in the period from the increase (decrease) in fair value of foreign currency derivatives not designated as hedging instruments.

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Amount before tax of increase (decrease) in accumulated gain (loss) from derivative instruments designated and qualifying as the effective portion of cash flow hedges and an entity's share of an equity investee's increase (decrease) in deferred hedging gain (loss).

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