Stockholders' Equity (Details) - USD ($) $ in Millions		3 Months Ended				6 Months Ended
	May 01, 2019	Oct. 31, 2020	Jul. 31, 2020	Oct. 31, 2019	Jul. 31, 2019	Oct. 31, 2020	Oct. 31, 2019
Beginning balance	$ 1,647	$ 2,150	$ 1,975	$ 1,663	$ 1,647	$ 1,975	$ 1,647
Net income		240	324	282	186	564	468
Net other comprehensive income (loss)		15	24	7	(1)	39	6
Declaration of cash dividends			(167)		(158)
Acquisition of treasury stock					(1)
Stock-based compensation expense		3	3	3	3
Stock issued under compensation plans		5	10	11	16
Loss on issuance of treasury stock issued under compensation plans		(10)	(19)	(24)	(29)
Ending balance		2,403	2,150	1,942	1,663	2,403	1,942
Additional Paid-in Capital [Member]
Beginning balance	0	0	0	1	0	0	0
Stock-based compensation expense		3	3	3	3
Loss on issuance of treasury stock issued under compensation plans		(3)	(3)	(4)	(2)
Ending balance		0	0	0	1	0	0
Retained Earnings [Member]
Beginning balance	2,238	2,849	2,708	2,282	2,238	2,708	2,238
Adoption of ASU 2018-02	43
Net income		240	324	282	186
Declaration of cash dividends			(167)		(158)
Loss on issuance of treasury stock issued under compensation plans		(7)	(16)	(20)	(27)
Ending balance		3,082	2,849	2,544	2,282	3,082	2,544
AOCI Attributable to Parent [Member]
Beginning balance	(363)	(523)	(547)	(407)	(363)	(547)	(363)
Adoption of ASU 2018-02	(43)
Net other comprehensive income (loss)		15	24	7	(1)
Ending balance		(508)	(523)	(400)	(407)	(508)	(400)
Treasury Stock, Common [Member]
Beginning balance	(300)	(248)	(258)	(285)	(300)	(258)	(300)
Acquisition of treasury stock					(1)
Stock issued under compensation plans		5	10	11	16
Ending balance		(243)	(248)	(274)	(285)	(243)	(274)
Common stock, Class A, voting [Member] | Common Stock [Member]
Beginning balance	25	25	25	25	25	25	25
Ending balance		25	25	25	25	25	25
Common stock, Class B, nonvoting [Member] | Common Stock [Member]
Beginning balance	$ 47	47	47	47	47	47	47
Ending balance		$ 47	$ 47	$ 47	$ 47	$ 47	$ 47