Supplemental Information (Net Sales by Geography) (Details) - USD ($) $ in Millions	12 Months Ended
	Apr. 30, 2016	Apr. 30, 2015	Apr. 30, 2014
Net sales:
Net sales	$ 4,011	$ 4,096	$ 3,946
UNITED STATES
Net sales:
Net sales	1,838	1,780	1,624
Europe [Member]
Net sales:
Net sales	1,242	1,270	1,264
Australia [Member]
Net sales:
Net sales	379	431	469
Other Countries [Member]
Net sales:
Net sales	$ 552	$ 615	$ 589