Fair Value Measurements (Details) (USD $) In Millions, unless otherwise specified	Jan. 31, 2014	Apr. 30, 2013
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Short-term borrowings	$ 9	$ 3
Long-term debt	952	1,011
Currency derivatives [Member]
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Currency derivatives	2	4
Fair Value, Measurements, Recurring [Member]
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Short-term borrowings	9	3
Current portion of long-term debt		2
Long-term debt	952	1,011
Fair Value, Measurements, Recurring [Member] | Currency derivatives [Member]
Financial Instruments, Financial Assets, Balance Sheet Groupings [Abstract]
Currency derivatives	11	5
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Currency derivatives	2	4
Fair Value, Measurements, Recurring [Member] | Level 1 [Member]
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Short-term borrowings	0	0
Current portion of long-term debt		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	9	3
Current portion of long-term debt		2
Long-term debt	952	1,011
Fair Value, Measurements, Recurring [Member] | Level 2 [Member] | Currency derivatives [Member]
Financial Instruments, Financial Assets, Balance Sheet Groupings [Abstract]
Currency derivatives	11	5
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Currency derivatives	2	4
Fair Value, Measurements, Recurring [Member] | Level 3 [Member]
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Short-term borrowings	0	0
Current portion of long-term debt		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