Consolidated Statements of Stockholders' Equity - USD ($) $ in Millions		Total	Common Stock [Member] Common stock, Class A, voting [Member]	Common Stock [Member] Common Stock, Class B, nonvoting [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	AOCI Attributable to Parent [Member]	Treasury Stock, Common [Member]
Beginning Balance at Apr. 30, 2018		$ 1,316	$ 25	$ 47	$ 4	$ 1,730	$ (378)	$ (112)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income		835				835
Net other comprehensive income (loss)		15					15
Cash dividends		(310)				(310)
Acquisition of treasury stock		(207)						(207)
Stock-based compensation expense		14			14
Stock issued under compensation plans		19						19
Loss on issuance of treasury stock issued under compensation plans		(30)			(18)	(12)
Other		(5)				(5)
Ending Balance at Apr. 30, 2019		1,647	25	47	0	2,238	(363)	(300)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Reclassification of tax effects	[1]					43	(43)
Net income		827				827
Net other comprehensive income (loss)		(141)					(141)
Cash dividends		(325)				(325)
Acquisition of treasury stock		(1)						(1)
Stock-based compensation expense		11			11
Stock issued under compensation plans		43						43
Loss on issuance of treasury stock issued under compensation plans		(86)			(11)	(75)
Ending Balance at Apr. 30, 2020		1,975	25	47	0	2,708	(547)	(258)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income		903				903
Net other comprehensive income (loss)		125					125
Cash dividends		(338)				(338)
Acquisition of treasury stock		0						0
Stock-based compensation expense		12			12
Stock issued under compensation plans		21						21
Loss on issuance of treasury stock issued under compensation plans		(42)			(12)	(30)
Ending Balance at Apr. 30, 2021		$ 2,656	$ 25	$ 47	$ 0	$ 3,243	$ (422)	$ (237)

[1] Reflects adoption of Accounting Standards Update No. 2018-02, Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income (AOCI), effective May 1, 2019.