Supplemental Information (Net Sales by Geography) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Apr. 30, 2013	Apr. 30, 2012	Apr. 30, 2011
Net sales:
Net Sales, United States	$ 1,562	$ 1,522	$ 1,525
Net sales	3,784	3,614	3,404
Europe [Member]
Net sales:
Net Sales, Europe, Australia, and Other	1,147	1,073	981
Australia [Member]
Net sales:
Net Sales, Europe, Australia, and Other	510	482	429
Other [Member]
Net sales:
Net Sales, Europe, Australia, and Other	$ 565	$ 537	$ 469