Adoption of Updated Accounting Standards Impact of Adopting ASC 606 (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Apr. 30, 2019	Apr. 30, 2018	Apr. 30, 2017	Jan. 31, 2019	Apr. 30, 2016
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Sales	$ 4,276	$ 4,201	$ 3,857
Excise taxes	952	953	863
Net sales	3,324	3,248	2,994
Cost of sales	1,158	1,046	973
Gross profit	2,166	2,202	2,021
Advertising expenses	396	405	372
Selling, general, and administrative expenses	641	765	657
Other expense (income), net	(15)	(16)	(18)
Operating income	1,144	1,048	1,010
Non-operating postretirement expense	22	9	21
Interest income	(8)	(6)	(3)
Interest expense	88	68	59
Income before income taxes	1,042	977	933
Income taxes	207	260	264
Net income	$ 835	$ 717	$ 669
Basic earnings per share (dollars per share)	$ 1.74	$ 1.49	$ 1.38
Diluted earnings per share (dollars per share)	$ 1.73	$ 1.48	$ 1.37
Other current assets	$ 283	$ 298
Deferred tax assets	16	16
Total assets	5,139	4,976
Accounts payable and accrued expenses	544	581
Accrued income taxes	9	25
Deferred tax liabilities	145	85
Total liabilities	3,492	3,660
Retained earnings	2,238	1,730
Total stockholders’ equity	1,647	$ 1,316	$ 1,370		$ 1,562
Accounting Standards Update 2014-09 [Member] | Difference between Revenue Guidance in Effect before and after Topic 606 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Sales	(23)
Excise taxes	0
Net sales	(23)
Cost of sales	1
Gross profit	(24)
Advertising expenses	(14)
Selling, general, and administrative expenses	(8)
Other expense (income), net	0
Operating income	(2)
Non-operating postretirement expense	0
Interest income	0
Interest expense	0
Income before income taxes	(2)
Income taxes	(1)
Net income	$ (1)
Basic earnings per share (dollars per share)	$ 0.00
Diluted earnings per share (dollars per share)	$ 0.00
Other current assets				$ (1)
Deferred tax assets	$ 1
Total assets	0
Accounts payable and accrued expenses	33
Accrued income taxes	1
Deferred tax liabilities	(8)
Total liabilities	26
Retained earnings	(26)
Total stockholders’ equity	(26)
Calculated under Revenue Guidance in Effect before Topic 606 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Sales	4,299
Excise taxes	952
Net sales	3,347
Cost of sales	1,157
Gross profit	2,190
Advertising expenses	410
Selling, general, and administrative expenses	649
Other expense (income), net	(15)
Operating income	1,146
Non-operating postretirement expense	22
Interest income	(8)
Interest expense	88
Income before income taxes	1,044
Income taxes	208
Net income	$ 836
Basic earnings per share (dollars per share)	$ 1.74
Diluted earnings per share (dollars per share)	$ 1.73
Other current assets	$ 284
Deferred tax assets	15
Total assets	5,139
Accounts payable and accrued expenses	511
Accrued income taxes	8
Deferred tax liabilities	153
Total liabilities	3,466
Retained earnings	2,264
Total stockholders’ equity	$ 1,673