Condensed Consolidated Statements of Comprehensive Income (Unaudited) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Oct. 31, 2015	Oct. 31, 2014	Oct. 31, 2015	Oct. 31, 2014
Statement of Comprehensive Income [Abstract]
Net income	$ 200	$ 208	$ 356	$ 358
Other comprehensive income (loss), net of tax:
Currency translation adjustments	(4)	(30)	(28)	(46)
Cash flow hedge adjustments	(4)	22	12	27
Postretirement benefits adjustments	6	12	10	16
Net other comprehensive income (loss)	(2)	4	(6)	(3)
Comprehensive income	$ 198	$ 212	$ 350	$ 355