Condensed Statements of Consolidated Shareholders' Equity (Unaudited) - USD ($) $ in Millions	Total	Common Shares	Additional Capital	Retained Income	Accumulated Other Comprehensive Income (Loss)
Balance at Apr. 30, 2020	$ 8,190.9	$ 29.0	$ 5,794.1	$ 2,746.8	$ (379.0)
Balance, shares at Apr. 30, 2020		114,072,726
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	237.0			237.0
Other comprehensive income (loss)	18.1				18.1
Comprehensive Income	255.1
Purchase of treasury shares	(4.6)	$ 0.0	(5.5)	0.9
Purchase of treasury shares, shares		(42,194)
Stock plans	6.2	$ 0.0	6.2
Stock plans, shares		56,910
Cash dividends declared	(102.4)			(102.4)
Other	0.0	$ (0.5)	0.5	0.0
Balance at Jul. 31, 2020	8,345.2	$ 28.5	5,795.3	2,882.3	(360.9)
Balance, shares at Jul. 31, 2020		114,087,442
Balance at Apr. 30, 2020	8,190.9	$ 29.0	5,794.1	2,746.8	(379.0)
Balance, shares at Apr. 30, 2020		114,072,726
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	729.3
Other comprehensive income (loss)	75.5
Comprehensive Income	804.8
Balance at Jan. 31, 2021	8,211.6	$ 27.4	5,591.6	2,896.1	(303.5)
Balance, shares at Jan. 31, 2021		109,789,150
Balance at Jul. 31, 2020	8,345.2	$ 28.5	5,795.3	2,882.3	(360.9)
Balance, shares at Jul. 31, 2020		114,087,442
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	230.8			230.8
Other comprehensive income (loss)	33.4				33.4
Comprehensive Income	264.2
Purchase of treasury shares	(1.6)	$ 0.0	(1.7)	0.1
Purchase of treasury shares, shares		(14,769)
Stock plans	9.5	$ 0.0	9.5
Stock plans, shares		24,588
Cash dividends declared	(102.3)			(102.3)
Balance at Oct. 31, 2020	8,515.0	$ 28.5	5,803.1	3,010.9	(327.5)
Balance, shares at Oct. 31, 2020		114,097,261
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	261.5			261.5
Other comprehensive income (loss)	24.0				24.0
Comprehensive Income	285.5
Purchase of treasury shares	(497.9)	$ (1.1)	(219.0)	(277.8)
Purchase of treasury shares, shares		(4,301,631)
Stock plans	7.5	$ 0.0	7.5
Stock plans, shares		(6,480)
Cash dividends declared	(98.5)			(98.5)
Balance at Jan. 31, 2021	8,211.6	$ 27.4	5,591.6	2,896.1	(303.5)
Balance, shares at Jan. 31, 2021		109,789,150
Balance at Apr. 30, 2021	$ 8,124.8	$ 27.1	5,527.6	2,847.5	(277.4)
Balance, shares at Apr. 30, 2021	108,300,000	108,339,057
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	$ 153.9			153.9
Other comprehensive income (loss)	(4.2)				(4.2)
Comprehensive Income	149.7
Purchase of treasury shares	(6.8)	$ 0.0	(6.1)	(0.7)
Purchase of treasury shares, shares		(50,203)
Stock plans	9.5	$ 0.0	9.5
Stock plans, shares		71,140
Cash dividends declared	(106.9)			(106.9)
Balance at Jul. 31, 2021	8,170.3	$ 27.1	5,531.0	2,893.8	(281.6)
Balance, shares at Jul. 31, 2021		108,359,994
Balance at Apr. 30, 2021	$ 8,124.8	$ 27.1	5,527.6	2,847.5	(277.4)
Balance, shares at Apr. 30, 2021	108,300,000	108,339,057
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	$ 429.6
Other comprehensive income (loss)	8.1
Comprehensive Income	437.7
Balance at Jan. 31, 2022	$ 8,266.9	$ 27.1	5,553.6	2,955.5	(269.3)
Balance, shares at Jan. 31, 2022	108,500,000	108,462,330
Balance at Jul. 31, 2021	$ 8,170.3	$ 27.1	5,531.0	2,893.8	(281.6)
Balance, shares at Jul. 31, 2021		108,359,994
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	206.0			206.0
Other comprehensive income (loss)	11.1				11.1
Comprehensive Income	217.1
Purchase of treasury shares	(0.7)	$ 0.0	(0.6)	(0.1)
Purchase of treasury shares, shares		(5,676)
Stock plans	6.6	$ 0.0	6.6
Stock plans, shares		8,521
Cash dividends declared	(106.9)			(106.9)
Balance at Oct. 31, 2021	8,286.4	$ 27.1	5,537.0	2,992.8	(270.5)
Balance, shares at Oct. 31, 2021		108,362,839
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	69.7			69.7
Other comprehensive income (loss)	1.2				1.2
Comprehensive Income	70.9
Purchase of treasury shares	(0.2)	$ 0.0	(0.2)	0.0
Purchase of treasury shares, shares		(1,505)
Stock plans	16.8	$ 0.0	16.8
Stock plans, shares		100,996
Cash dividends declared	(107.0)			(107.0)
Balance at Jan. 31, 2022	$ 8,266.9	$ 27.1	$ 5,553.6	$ 2,955.5	$ (269.3)
Balance, shares at Jan. 31, 2022	108,500,000	108,462,330