Fair Value of Financial Instruments (Details) (USD $) In Millions, unless otherwise specified	Apr. 30, 2013	Apr. 30, 2012
Carrying Amount [Member]
Assets:
Cash and cash equivalents	$ 204	$ 338
Liabilities:
Short-term borrowings	3	4
Current portion of long-term debt	2	3
Long-term debt	997	503
Carrying Amount [Member] | Commodity derivatives [Member]
Assets:
Derivative assets	0	0
Liabilities:
Derivative liabilities	0	1
Carrying Amount [Member] | Currency derivatives [Member]
Assets:
Currency derivatives, assets	5	1
Liabilities:
Currency derivatives, liabilities	4	7
Carrying Amount [Member] | Interest rate swaps [Member]
Assets:
Derivative assets	0	2
Fair Value [Member]
Assets:
Cash and cash equivalents	204	338
Liabilities:
Short-term borrowings	3	4
Current portion of long-term debt	2	3
Long-term debt	1,011	534
Fair Value [Member] | Commodity derivatives [Member]
Assets:
Derivative assets	0	0
Liabilities:
Derivative liabilities	0	1
Fair Value [Member] | Currency derivatives [Member]
Assets:
Currency derivatives, assets	5	1
Liabilities:
Currency derivatives, liabilities	4	7
Fair Value [Member] | Interest rate swaps [Member]
Assets:
Derivative assets	$ 0	$ 2