Condensed Consolidated Statements of Comprehensive Income (Unaudited) - USD ($) $ in Millions	3 Months Ended
Jul. 31, 2018	Jul. 31, 2017
Statement of Comprehensive Income [Abstract]
Net income	$ 200	$ 178
Other comprehensive income (loss), net of tax:
Currency translation adjustments	(12)	34
Cash flow hedge adjustments	23	(23)
Postretirement benefits adjustments	3	3
Net other comprehensive income (loss)	14	14
Comprehensive income	$ 214	$ 192

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