Income Taxes (Deferred Tax Assets and Liabilities) (Details) (USD $) In Millions, unless otherwise specified	Apr. 30, 2014	Apr. 30, 2013
Deferred tax assets:
Postretirement and other benefits	$ 139	$ 136
Accrued liabilities and other	30	26
Inventories	8	8
Loss and credit carryforwards	52	39
Valuation allowance	(34)	(25)
Total deferred tax assets, net	195	184
Deferred tax liabilities:
Intangible assets	(184)	(258)
Property, plant, and equipment	(49)	(50)
Other	(21)	(20)
Total deferred tax liabilities	(254)	(328)
Net deferred tax liability	$ (59)	$ (144)