Quarterly Results of Operations (Unaudited) (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended																12 Months Ended
	Apr. 30, 2020		Jan. 31, 2020		Oct. 31, 2019		Jul. 31, 2019		Apr. 30, 2019		Jan. 31, 2019		Oct. 31, 2018		Jul. 31, 2018		Apr. 30, 2020	Apr. 30, 2019	Apr. 30, 2018
Quarterly Financial Data [Abstract]
Net sales	$ 2,092.0		$ 1,972.3		$ 1,957.8		$ 1,778.9		$ 1,902.1		$ 2,011.9		$ 2,021.5		$ 1,902.5		$ 7,801.0	$ 7,838.0	$ 7,357.1
Gross Profit	788.4		760.0		754.0		699.6		692.4		773.8		771.3		678.2		3,002.0	2,915.7	2,836.1
Net income	$ 226.3		$ 187.4		$ 211.2		$ 154.6		$ 71.5		$ 121.4		$ 188.5		$ 133.0		$ 779.5	$ 514.4	$ 1,338.6
Net Income (in dollars per share)	$ 1.98	[1]	$ 1.64	[1]	$ 1.85	[1]	$ 1.36	[1]	$ 0.63	[1]	$ 1.07	[1]	$ 1.66	[1]	$ 1.17	[1]	$ 6.84	$ 4.52	$ 11.79
Net Income - Assuming Dilution (in dollars per share)	1.98	[1]	1.64	[1]	1.85	[1]	1.36	[1]	0.63	[1]	1.07	[1]	1.66	[1]	1.17	[1]	6.84	4.52	11.78
Dividends declared per common share	$ 0.88		$ 0.88		$ 0.88		$ 0.88		$ 0.85		$ 0.85		$ 0.85		$ 0.85		$ 3.52	$ 3.40	$ 3.12

[1] Annual net income per common share may not equal the sum of the individual quarters due to differences in the average number of shares outstanding during the respective periods, primarily due to share repurchases.