Derivative Financial Instruments and Hedging Activities (Details 1) - USD ($) $ in Millions	3 Months Ended
Jul. 31, 2019	Apr. 30, 2019
Fair values of derivative instruments
Derivative Asset, Fair Value, Gross Asset	$ 57	$ 43
Derivative Liability, Fair Value, Gross Liability	$ 10	9
Document Period End Date	Jul. 31, 2019
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		21
Derivative Liability, Fair Value, Gross Liability		(2)
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		22
Derivative Liability, Fair Value, Gross Liability		(1)
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		0
Derivative Liability, Fair Value, Gross Liability		(5)
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		0
Derivative Liability, Fair Value, Gross Liability		$ (1)
Fair value of derivatives in a gain position [Member] \| 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	$ 30
Fair value of derivatives in a gain position [Member] \| 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	27
Fair value of derivatives in a gain position [Member] \| 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	0
Fair value of derivatives in a gain position [Member] \| 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	0
Fair value of derivatives in a loss position [Member] \| Currency derivatives [Member] \| Designated as Hedging Instrument [Member] \| Cash Flow Hedging [Member] \| Other Current Assets [Member]
Fair values of derivative instruments
Derivative Liability, Fair Value, Gross Liability	(2)
Fair value of derivatives in a loss position [Member] \| Currency derivatives [Member] \| Designated as Hedging Instrument [Member] \| Cash Flow Hedging [Member] \| Other Assets [Member]
Fair values of derivative instruments
Derivative Liability, Fair Value, Gross Liability	0
Fair value of derivatives in a loss position [Member] \| Currency derivatives [Member] \| Designated as Hedging Instrument [Member] \| Cash Flow Hedging [Member] \| Accrued Expenses [Member]
Fair values of derivative instruments
Derivative Liability, Fair Value, Gross Liability	(6)
Fair value of derivatives in a loss position [Member] \| Currency derivatives [Member] \| Designated as Hedging Instrument [Member] \| Cash Flow Hedging [Member] \| Other Liabilities [Member]
Fair values of derivative instruments
Derivative Liability, Fair Value, Gross Liability	$ (2)

Fair value of derivatives in a gain position [Member] | Currency derivatives [Member] | Designated as Hedging Instrument [Member] | Cash Flow Hedging [Member] | Other Current Assets [Member]

Fair value of derivatives in a gain position [Member] | Currency derivatives [Member] | Designated as Hedging Instrument [Member] | Cash Flow Hedging [Member] | Other Assets [Member]

Fair value of derivatives in a gain position [Member] | Currency derivatives [Member] | Designated as Hedging Instrument [Member] | Cash Flow Hedging [Member] | Accrued Expenses [Member]

Fair value of derivatives in a gain position [Member] | Currency derivatives [Member] | Designated as Hedging Instrument [Member] | Cash Flow Hedging [Member] | Other Liabilities [Member]

Fair value of derivatives in a loss position [Member] | Currency derivatives [Member] | Designated as Hedging Instrument [Member] | Cash Flow Hedging [Member] | Other Current Assets [Member]

Fair value of derivatives in a loss position [Member] | Currency derivatives [Member] | Designated as Hedging Instrument [Member] | Cash Flow Hedging [Member] | Other Assets [Member]

Fair value of derivatives in a loss position [Member] | Currency derivatives [Member] | Designated as Hedging Instrument [Member] | Cash Flow Hedging [Member] | Accrued Expenses [Member]

Fair value of derivatives in a loss position [Member] | Currency derivatives [Member] | Designated as Hedging Instrument [Member] | Cash Flow Hedging [Member] | Other Liabilities [Member]