Derivative Financial Instruments and Hedging Activities (Details 1) - USD ($) $ in Millions	Jul. 31, 2020	Apr. 30, 2020
Fair values of derivative instruments
Derivative Asset, Fair Value, Gross Asset	$ 32	$ 79
Derivative Liability, Fair Value, Gross Liability	14	3
Currency derivatives [Member] | Designated as Hedging Instrument [Member] | Cash Flow Hedging [Member] | Other Current Assets [Member]
Fair values of derivative instruments
Derivative Asset, Fair Value, Gross Asset	19	49
Derivative Liability, Fair Value, Gross Liability	(2)	(1)
Currency derivatives [Member] | Designated as Hedging Instrument [Member] | Cash Flow Hedging [Member] | Other Assets [Member]
Fair values of derivative instruments
Derivative Asset, Fair Value, Gross Asset	4	30
Derivative Liability, Fair Value, Gross Liability	(1)	0
Currency derivatives [Member] | Designated as Hedging Instrument [Member] | Cash Flow Hedging [Member] | Accrued Expenses [Member]
Fair values of derivative instruments
Derivative Asset, Fair Value, Gross Asset	2	0
Derivative Liability, Fair Value, Gross Liability	(3)	0
Currency derivatives [Member] | Designated as Hedging Instrument [Member] | Cash Flow Hedging [Member] | Other Liabilities [Member]
Fair values of derivative instruments
Derivative Asset, Fair Value, Gross Asset	3	0
Derivative Liability, Fair Value, Gross Liability	(8)	0
Currency derivatives [Member] | Not designated as hedges [Member] | Other Current Assets [Member]
Fair values of derivative instruments
Derivative Asset, Fair Value, Gross Asset	4	0
Derivative Liability, Fair Value, Gross Liability	0	0
Currency derivatives [Member] | Not designated as hedges [Member] | Other Assets [Member]
Fair values of derivative instruments
Derivative Asset, Fair Value, Gross Asset	0	0
Derivative Liability, Fair Value, Gross Liability	0	0
Currency derivatives [Member] | Not designated as hedges [Member] | Accrued Expenses [Member]
Fair values of derivative instruments
Derivative Asset, Fair Value, Gross Asset	0	0
Derivative Liability, Fair Value, Gross Liability	0	(2)
Currency derivatives [Member] | Not designated as hedges [Member] | Other Liabilities [Member]
Fair values of derivative instruments
Derivative Asset, Fair Value, Gross Asset	0	0
Derivative Liability, Fair Value, Gross Liability	$ 0	$ 0