Fair Value Measurements (Details) (USD $) In Millions, unless otherwise specified	Oct. 31, 2014	Apr. 30, 2014
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Short-term borrowings	$ 124	$ 8
Long-term debt	975	963
Currency derivatives [Member]
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Currency derivatives	0	7
Fair Value, Measurements, Recurring [Member]
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Short-term borrowings	124	8
Long-term debt	975	963
Fair Value, Measurements, Recurring [Member] | Currency derivatives [Member]
Financial Instruments, Financial Assets, Balance Sheet Groupings [Abstract]
Currency derivatives	51	7
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Currency derivatives		7
Fair Value, Measurements, Recurring [Member] | Level 1 [Member]
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Short-term borrowings	0	0
Long-term debt	0	0
Fair Value, Measurements, Recurring [Member] | Level 1 [Member] | Currency derivatives [Member]
Financial Instruments, Financial Assets, Balance Sheet Groupings [Abstract]
Currency derivatives	0	0
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Currency derivatives		0
Fair Value, Measurements, Recurring [Member] | Level 2 [Member]
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Short-term borrowings	124	8
Long-term debt	975	963
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Currency derivatives [Member]
Financial Instruments, Financial Assets, Balance Sheet Groupings [Abstract]
Currency derivatives	51	7
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Currency derivatives		7
Fair Value, Measurements, Recurring [Member] | Level 3 [Member]
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Short-term borrowings	0	0
Long-term debt	0	0
Fair Value, Measurements, Recurring [Member] | Level 3 [Member] | Currency derivatives [Member]
Financial Instruments, Financial Assets, Balance Sheet Groupings [Abstract]
Currency derivatives	0	0
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Currency derivatives		$ 0