Condensed Consolidated Statements of Comprehensive Income (Unaudited) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Oct. 31, 2013	Oct. 31, 2012	Oct. 31, 2013	Oct. 31, 2012
Statement of Comprehensive Income [Abstract]
Net income	$ 206	$ 173	$ 349	$ 320
Other comprehensive income (loss), net of tax:
Currency translation adjustments	7	12	(5)	(1)
Postretirement benefits adjustments	14	5	19	9
Net gain (loss) on cash flow hedges	(10)	(9)	(4)	(1)
Net other comprehensive income (loss)	11	8	10	7
Comprehensive income	$ 217	$ 181	$ 359	$ 327