Consolidated Statements of Comprehensive Income (USD $) In Millions, unless otherwise specified	12 Months Ended
	Apr. 30, 2014	Apr. 30, 2013	Apr. 30, 2012
Statement of Comprehensive Income [Abstract]
Net income	$ 659	$ 591	$ 513
Other comprehensive income (loss), net of tax:
Net other comprehensive income (loss)	23	19	(99)
Currency translation adjustments	(4)	17	(55)
Cash flow hedge adjustments	(4)	3	11
Postretirement benefits adjustments	31	(1)	(55)
Comprehensive income	$ 682	$ 610	$ 414