CONDENSED CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY - USD ($) $ in Millions	Total	Common Stock	Additional Paid-In Capital	Retained Earnings	Accumulated Other Comprehensive Income (Loss)	Common Stock in Treasury at Cost
Balance at Sep. 30, 2019	$ 2,599.8	$ 0.7	$ 808.5	$ 2,505.0	$ (201.6)	$ (512.8)
Net income	144.3			144.3
Employee pension and postretirement benefits, net of tax	1.4				1.4
Currency translation adjustments	(8.9)				(8.9)
Cash dividends	(40.9)			(40.9)
Repurchases of Common Stock	(40.8)					(40.8)
Exercise of stock options	23.6		(10.7)			34.3
Stock-based compensation expense	17.7		17.7
Payment of stock-based restricted and performance shares			(18.2)			18.2
Shares tendered for taxes on stock-based compensation	(8.5)					(8.5)
Other	1.3		(2.3)		0.2	3.4
Balance at Mar. 31, 2020	2,689.0	0.7	795.0	2,608.4	(208.9)	(506.2)
Balance at Dec. 31, 2019	2,681.1	0.7	794.1	2,560.3	(181.9)	(492.1)
Net income	68.6			68.6
Employee pension and postretirement benefits, net of tax	0.7				0.7
Currency translation adjustments	(28.4)				(28.4)
Cash dividends	(20.5)			(20.5)
Repurchases of Common Stock	(31.4)					(31.4)
Exercise of stock options	8.8		(4.8)			13.6
Stock-based compensation expense	8.3		8.3
Payment of stock-based restricted and performance shares			(0.3)			0.3
Other	1.8		(2.3)		0.7	3.4
Balance at Mar. 31, 2020	2,689.0	0.7	795.0	2,608.4	(208.9)	(506.2)
Balance at Sep. 30, 2020	2,850.7	0.7	800.9	2,747.7	(198.4)	(500.2)
Net income	169.1			169.1
Employee pension and postretirement benefits, net of tax	2.4				2.4
Currency translation adjustments	11.8				11.8
Cash dividends	(45.2)			(45.2)
Exercise of stock options	22.8		(1.5)			24.3
Stock-based compensation expense	14.9		14.9
Payment of stock-based restricted and performance shares			(16.0)			16.0
Shares tendered for taxes on stock-based compensation	(8.0)					(8.0)
Other	(0.3)			(0.6)	0.3
Balance at Mar. 31, 2021	3,018.2	0.7	798.3	2,871.0	(183.9)	(467.9)
Balance at Dec. 31, 2020	2,932.6	0.7	791.4	2,793.5	(165.5)	(487.5)
Net income	99.6			99.6
Employee pension and postretirement benefits, net of tax	1.2				1.2
Currency translation adjustments	(20.0)				(20.0)
Cash dividends	(22.7)			(22.7)
Exercise of stock options	18.2		(0.6)			18.8
Stock-based compensation expense	8.3		8.3
Payment of stock-based restricted and performance shares			(0.8)			0.8
Other	1.0			0.6	0.4
Balance at Mar. 31, 2021	$ 3,018.2	$ 0.7	$ 798.3	$ 2,871.0	$ (183.9)	$ (467.9)