CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY/(DEFICIT) - USD ($) shares in Thousands, $ in Millions	Total	Common Stock	Additional Paid-in Capital	Retained (Losses)/Earnings	Accumulated Other Comprehensive (Loss)/Income	Treasury Stock
Beginning balance (in shares) at Sep. 30, 2022		71,270
Beginning balance at Sep. 30, 2022	$ 130.6	$ 0.8	$ 828.7	$ (304.7)	$ (145.3)	$ (248.9)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net earnings	49.0			49.0
Share-based payments	4.6		4.6
Activity under stock plans (in shares)		142
Activity under stock plans	(1.9)		(8.5)	(0.3)		6.9
Dividends to common shareholders	(21.9)		(21.9)
Other comprehensive loss	(29.6)				(29.6)
Ending balance (in shares) at Dec. 31, 2022		71,412
Ending balance at Dec. 31, 2022	130.8	$ 0.8	802.9	(256.0)	(174.9)	(242.0)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net earnings	40.0			40.0
Share-based payments	8.3		8.3
Activity under stock plans (in shares)		65
Activity under stock plans	0.0		(2.8)	0.0		2.8
Dividends to common shareholders	(22.0)		22.0	0.0
Other comprehensive loss	(8.7)				(8.7)
Ending balance (in shares) at Mar. 31, 2023		71,477
Ending balance at Mar. 31, 2023	148.4	$ 0.8	786.4	(216.0)	(183.6)	(239.2)
Beginning balance (in shares) at Sep. 30, 2023		71,500
Beginning balance at Sep. 30, 2023	210.7	$ 0.8	750.5	(164.8)	(137.7)	(238.1)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net earnings	1.9			1.9
Share-based payments	6.4		6.4
Activity under stock plans (in shares)		277
Activity under stock plans	(4.7)		(16.3)	(1.4)		13.0
Dividends to common shareholders	(22.1)		(22.1)
Other comprehensive loss	(21.6)				(21.6)
Ending balance (in shares) at Dec. 31, 2023		71,777
Ending balance at Dec. 31, 2023	170.6	$ 0.8	718.5	(164.3)	(159.3)	(225.1)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net earnings	32.4			32.4
Share-based payments	7.1		7.1
Activity under stock plans (in shares)		13
Activity under stock plans	0.0		(0.5)			0.5
Dividends to common shareholders	(22.3)		(22.3)	0.0
Other comprehensive loss	3.5				3.5
Ending balance (in shares) at Mar. 31, 2024		71,790
Ending balance at Mar. 31, 2024	$ 191.3	$ 0.8	$ 702.8	$ (131.9)	$ (155.8)	$ (224.6)