Derivative Financial Instruments and Hedging Activities (Gain (Loss) on Derivatives Recognized in Consolidated Statement of Operations) (Details) - USD ($) $ in Millions	12 Months Ended
	Apr. 30, 2021	Apr. 30, 2020	Apr. 30, 2019
Total amounts presented in the accompanying condensed consolidated statements of operations for line items affected by the net gains (losses) shown above: [Abstract]
Sales	$ 4,526	$ 4,306	$ 4,276
Other income (expense), net	15	(11)	15
Foreign Currency Denominated Debt [Member]
Foreign currency-denominated debt designated as net investment hedge: [Abstract]
Net gain (loss) recognized in AOCI	(73)	22	45
Currency derivatives [Member]
Currency derivatives designated as cash flow hedges: [Abstract]
Net gain (loss) recognized in AOCI	(78)	61	69
Currency derivatives [Member] | Sales [Member]
Currency derivatives designated as cash flow hedges: [Abstract]
Net gain (loss) reclassified from AOCI into earnings	21	23	6
Currency derivatives not designated as hedging instruments: [Abstract]
Net gain (loss) recognized in earnings	(13)	4	6
Currency derivatives [Member] | Other Income (Expense), Net [Member]
Currency derivatives not designated as hedging instruments: [Abstract]
Net gain (loss) recognized in earnings	$ 17	$ (14)	$ 6