Fair Value of Financial Instruments (Details) (USD $) In Millions, unless otherwise specified	Jul. 31, 2014	Apr. 30, 2014	Jul. 31, 2013	Apr. 30, 2013
Assets:
Cash and cash equivalents, Carrying Amount	$ 460	$ 437	$ 217	$ 204
Cash and cash equivalents, Fair Value	460	437
Liabilities:
Short-term borrowings, Carrying Amount	13	8
Short-term borrowings, Fair Value	13	8
Long-term debt, Carrying Amount	998	997
Long-term debt, Fair Value	967	963
Currency derivatives [Member]
Assets:
Currency derivatives, Fair Value	3	7
Liabilities:
Currency derivatives, Fair Value	5	7
Reported Value Measurement [Member]
Assets:
Cash and cash equivalents, Carrying Amount	460	437
Liabilities:
Short-term borrowings, Carrying Amount	13	8
Long-term debt, Carrying Amount	998	997
Reported Value Measurement [Member] | Currency derivatives [Member]
Assets:
Currency derivatives, Carrying Amount	3	7
Liabilities:
Currency derivatives, Carrying Amount	$ 5	$ 7