Consolidated Statements of Comprehensive Income - USD ($) $ in Millions	12 Months Ended
Apr. 30, 2019	Apr. 30, 2018	Apr. 30, 2017
Statement of Comprehensive Income [Abstract]
Net income	$ 835	$ 717	$ 669
Other comprehensive income (loss), net of tax:
Currency translation adjustments	(27)	24	(73)
Cash flow hedge adjustments	48	(28)	0
Postretirement benefits adjustments	(6)	16	33
Net other comprehensive income (loss)	15	12	(40)
Comprehensive income	$ 850	$ 729	$ 629

Amount after tax of increase (decrease) in equity from transactions and other events and circumstances from net income and other comprehensive income, attributable to parent entity. Excludes changes in equity resulting from investments by owners and distributions to owners.

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