Condensed Consolidated Statements of Comprehensive Income (Unaudited) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Jul. 31, 2013	Jul. 31, 2012
Statement of Comprehensive Income [Abstract]
Net income	$ 143	$ 147
Other comprehensive income (loss), net of tax:
Currency translation adjustments	(12)	(13)
Postretirement benefits adjustments	5	4
Net gain on cash flow hedges	6	8
Net other comprehensive income (loss)	(1)	(1)
Comprehensive income	$ 142	$ 146