Consolidated Statements of Comprehensive Income - USD ($) $ in Millions	12 Months Ended
Apr. 30, 2018	Apr. 30, 2017	Apr. 30, 2016
Statement of Comprehensive Income [Abstract]
Net income	$ 717	$ 669	$ 1,067
Other comprehensive income (loss), net of tax:
Currency translation adjustments	24	(73)	(23)
Cash flow hedge adjustments	(28)	0	(17)
Postretirement benefits adjustments	16	33	(10)
Net other comprehensive income (loss)	12	(40)	(50)
Comprehensive income	$ 729	$ 629	$ 1,017

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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The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

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Amount, after tax and reclassification adjustment, of (increase) decrease in accumulated other comprehensive income for defined benefit plan, attributable to parent.

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Amount after tax and reclassification adjustments, of increase (decrease) in accumulated gain (loss) from derivative instruments designated and qualifying as the effective portion of cash flow hedges and an entity's share of an equity investee's increase (decrease) in deferred hedging gain (loss), attributable to parent entity.

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Amount after tax and reclassification adjustments of gain (loss) on foreign currency translation adjustments, foreign currency transactions designated and effective as economic hedges of a net investment in a foreign entity and intra-entity foreign currency transactions that are of a long-term-investment nature, attributable to parent entity.

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Amount after tax of other comprehensive income (loss) attributable to parent entity.

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