Stockholders' Equity (Details) - USD ($) $ in Millions		3 Months Ended						9 Months Ended
	May 01, 2019	Jan. 31, 2021	Oct. 31, 2020	Jul. 31, 2020	Jan. 31, 2020	Oct. 31, 2019	Jul. 31, 2019	Jan. 31, 2021	Jan. 31, 2020
Beginning balance	$ 1,647	$ 2,403	$ 2,150	$ 1,975	$ 1,942	$ 1,663	$ 1,647	$ 1,975	$ 1,647
Net income		219	240	324	231	282	186	783	699
Net other comprehensive income (loss)		19	15	24	8	7	(1)	58	14
Declaration of cash dividends		(172)		(167)	(167)		(158)
Acquisition of treasury stock							(1)
Stock-based compensation expense		3	3	3	2	3	3
Stock issued under compensation plans		3	5	10	11	11	16
Loss on issuance of treasury stock issued under compensation plans		(7)	(10)	(19)	(22)	(24)	(29)
Ending balance		2,468	2,403	2,150	2,005	1,942	1,663	2,468	2,005
Additional Paid-in Capital [Member]
Beginning balance	0	0	0	0	0	1	0	0	0
Stock-based compensation expense		3	3	3	2	3	3
Loss on issuance of treasury stock issued under compensation plans		(3)	(3)	(3)	(2)	(4)	(2)
Ending balance		0	0	0	0	0	1	0	0
Retained Earnings [Member]
Beginning balance	2,238	3,082	2,849	2,708	2,544	2,282	2,238	2,708	2,238
Adoption of ASU 2018-02	43
Net income		219	240	324	231	282	186
Declaration of cash dividends		(172)		(167)	(167)		(158)
Loss on issuance of treasury stock issued under compensation plans		(4)	(7)	(16)	(20)	(20)	(27)
Ending balance		3,125	3,082	2,849	2,588	2,544	2,282	3,125	2,588
AOCI Attributable to Parent [Member]
Beginning balance	(363)	(508)	(523)	(547)	(400)	(407)	(363)	(547)	(363)
Adoption of ASU 2018-02	(43)
Net other comprehensive income (loss)		19	15	24	8	7	(1)
Ending balance		(489)	(508)	(523)	(392)	(400)	(407)	(489)	(392)
Treasury Stock, Common [Member]
Beginning balance	(300)	(243)	(248)	(258)	(274)	(285)	(300)	(258)	(300)
Acquisition of treasury stock							(1)
Stock issued under compensation plans		3	5	10	11	11	16
Ending balance		(240)	(243)	(248)	(263)	(274)	(285)	(240)	(263)
Common stock, Class A, voting [Member] | Common Stock [Member]
Beginning balance	25	25	25	25	25	25	25	25	25
Ending balance		25	25	25	25	25	25	25	25
Common stock, Class B, nonvoting [Member] | Common Stock [Member]
Beginning balance	$ 47	47	47	47	47	47	47	47	47
Ending balance		$ 47	$ 47	$ 47	$ 47	$ 47	$ 47	$ 47	$ 47