Fair Value of Financial Instruments (Details) - USD ($) $ in Millions	Oct. 31, 2015	Apr. 30, 2015	Oct. 31, 2014	Apr. 30, 2014
Assets:
Cash and cash equivalents, Carrying Amount	$ 195	$ 370	$ 235	$ 437
Cash and cash equivalents, Fair Value	195	370
Liabilities:
Short-term borrowings, Carrying Amount	303	190
Short-term borrowings, Fair Value	303	190
Current portion of long-term debt, Carrying Amount	250	250
Current portion of long-term debt, Fair Value	251	253
Long-term debt, Carrying Amount	1,229	743
Long-term debt, Fair Value	1,232	735
Currency derivatives [Member]
Assets:
Currency derivatives, Fair Value	68	59
Liabilities:
Currency derivatives, Fair Value	4	18
Reported Value Measurement [Member]
Assets:
Cash and cash equivalents, Carrying Amount	195	370
Liabilities:
Short-term borrowings, Carrying Amount	303	190
Current portion of long-term debt, Carrying Amount	250	250
Long-term debt, Carrying Amount	1,229	743
Reported Value Measurement [Member] | Currency derivatives [Member]
Assets:
Currency derivatives, Carrying Amount	68	59
Liabilities:
Currency derivatives, Carrying Amount	$ 4	$ 18