Derivative Financial Instruments and Hedging Activities (Details) - USD ($) $ in Millions	3 Months Ended
Jul. 31, 2019	Jul. 31, 2018
Total amounts presented in the accompanying consolidated statements of operations for line items affected by the net gains (losses) shown above: [Abstract]
Sales	$ 978	$ 987
Other income (expense), net	6	7
Designated as Hedging Instrument [Member] \| Cash Flow Hedging [Member] \| Currency derivatives [Member]
Derivative Instruments [Abstract]
Net gain (loss) recognized in AOCI	15	27
Sales [Member] \| Designated as Hedging Instrument [Member] \| Cash Flow Hedging [Member] \| Currency derivatives [Member]
Derivative Instruments [Abstract]
Net gain (loss) reclassified from AOCI into earnings	4	(2)
Sales [Member] \| Not Designated as Hedging Instrument [Member] \| Currency derivatives [Member]
Derivative Instruments [Abstract]
Net gain (loss) recognized in earnings	0	3
Other Income [Member] \| Not Designated as Hedging Instrument [Member] \| Currency derivatives [Member]
Derivative Instruments [Abstract]
Net gain (loss) recognized in earnings	1	3
Foreign Currency Denominated Debt [Member] \| Designated as Hedging Instrument [Member] \| Net Investment Hedging [Member]
Non-Derivative Hedging Instruments [Abstract]
Net gain (loss) recognized in AOCI	$ 23	$ 28

Derivative Instruments [Abstract]

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Non-Derivative Hedging Instruments [Abstract]

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Nonderivative Instruments, Gain (Loss) Recognized in Other Comprehensive Income (Loss), Effective Portion, Net

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Total amounts presented in the accompanying consolidated statements of operations for line items affected by the net gains (losses) shown above: [Abstract]

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Amount of increase (decrease) in the fair value of derivatives recognized in the income statement.

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-Name Accounting Standards Codification
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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 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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The net amount of other operating income and expenses, the components of which are not separately disclosed on the income statement, from items that are associated with the entity's normal revenue producing operations.

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