Fair Value Measurements (Details) (USD $) In Millions, unless otherwise specified	Jul. 31, 2014	Apr. 30, 2014
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Short-term borrowings	$ 13	$ 8
Long-term debt	967	963
Currency derivatives [Member]
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Currency derivatives	5	7
Fair Value, Measurements, Recurring [Member]
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Short-term borrowings	13	8
Long-term debt	967	963
Fair Value, Measurements, Recurring [Member] | Currency derivatives [Member]
Financial Instruments, Financial Assets, Balance Sheet Groupings [Abstract]
Currency derivatives	3	7
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Currency derivatives	5	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	0
Fair Value, Measurements, Recurring [Member] | Level 2 [Member]
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Short-term borrowings	13	8
Long-term debt	967	963
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Currency derivatives [Member]
Financial Instruments, Financial Assets, Balance Sheet Groupings [Abstract]
Currency derivatives	3	7
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Currency derivatives	5	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	$ 0