CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY/(DEFICIT) - USD ($) shares in Thousands, $ in Millions	Total	Preferred Stock	Common Stock	Additional Paid-in Capital	Retained (Losses)/Earnings	Accumulated Other Comprehensive (Loss)/Income	Treasury Stock
Beginning Balance, Preferred Stock (in shares) at Sep. 30, 2021		2,156
Beginning Balance, Common Stock (in shares) at Sep. 30, 2021			66,864
Beginning Balance at Sep. 30, 2021	$ 355.7	$ 0.0	$ 0.7	$ 832.0	$ (5.0)	$ (230.4)	$ (241.6)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Share-based payments	1.3			1.3
Common stock purchased	0.0			15.0			(15.0)
Common stock purchased (in shares)			(451)
Activity under stock plans	(2.2)			(8.3)			6.1
Activity under stock plans (in shares)			133
Dividends to common shareholders	(20.1)				(20.1)
Dividends to preferred shareholders	(4.0)
Other Comprehensive Income (Loss), Net of Tax	18.7					18.7
Ending Balance at Dec. 31, 2021	409.4	$ 0.0	$ 0.7	840.0	30.9	(211.7)	(250.5)
Ending Balance, Common Stock (in shares) at Dec. 31, 2021			66,546
Ending Balance, Preferred Stock (in shares) at Dec. 31, 2021		2,156
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Mandatory preferred stock dividends					(4.0)
Net earnings	60.0				60.0
Beginning Balance, Preferred Stock (in shares) at Sep. 30, 2021		2,156
Beginning Balance, Common Stock (in shares) at Sep. 30, 2021			66,864
Beginning Balance at Sep. 30, 2021	355.7	$ 0.0	$ 0.7	832.0	(5.0)	(230.4)	(241.6)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Dividends to common shareholders	(63.6)
Ending Balance at Jun. 30, 2022	499.7	$ 0.0	$ 0.8	847.7	58.7	(157.9)	(249.6)
Ending Balance, Common Stock (in shares) at Jun. 30, 2022			71,254
Ending Balance, Preferred Stock (in shares) at Jun. 30, 2022		0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Mandatory preferred stock dividends	(4.0)
Net earnings	131.4
Beginning Balance, Preferred Stock (in shares) at Dec. 31, 2021		2,156
Beginning Balance, Common Stock (in shares) at Dec. 31, 2021			66,546
Beginning Balance at Dec. 31, 2021	409.4	$ 0.0	$ 0.7	840.0	30.9	(211.7)	(250.5)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Share-based payments	5.1			5.1
Activity under stock plans	(0.1)			(0.7)	(0.1)		0.7
Activity under stock plans (in shares)			17
Dividends to common shareholders	(21.9)				(21.9)
Other Comprehensive Income (Loss), Net of Tax	49.7					49.7
Ending Balance at Mar. 31, 2022	461.3	$ 0.0	$ 0.8	844.4	27.9	(162.0)	(249.8)
Ending Balance, Common Stock (in shares) at Mar. 31, 2022			71,250
Ending Balance, Preferred Stock (in shares) at Mar. 31, 2022		0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net earnings	19.0				19.0
Stock Issued During Period, Shares, Conversion of Convertible Securities		(2,156)	(4,687)
Stock Issued During Period, Value, Conversion of Convertible Securities	0.1		$ 0.1
Share-based payments	3.5			3.5
Activity under stock plans	0.0			(0.2)	0.0		0.2
Activity under stock plans (in shares)			4
Dividends to common shareholders	(21.6)				(21.6)
Other Comprehensive Income (Loss), Net of Tax	4.1					4.1
Ending Balance at Jun. 30, 2022	499.7	$ 0.0	$ 0.8	847.7	58.7	(157.9)	(249.6)
Ending Balance, Common Stock (in shares) at Jun. 30, 2022			71,254
Ending Balance, Preferred Stock (in shares) at Jun. 30, 2022		0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Mandatory preferred stock dividends	0.0
Net earnings	52.4				52.4
Net earnings	52.4
Ending Balance at Sep. 30, 2022	130.6		$ 0.8	828.7	(304.7)	(145.3)	(248.9)
Ending Balance, Common Stock (in shares) at Sep. 30, 2022			71,270
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock Issued During Period, Shares, Conversion of Convertible Securities			(4,700)
Share-based payments	4.6			4.6
Activity under stock plans	(1.9)			(8.5)	(0.3)		6.9
Activity under stock plans (in shares)			142
Dividends to common shareholders	(21.9)			(21.9)	0.0
Other Comprehensive Income (Loss), Net of Tax	(29.6)					(29.6)
Ending Balance at Dec. 31, 2022	130.8		$ 0.8	802.9	(256.0)	(174.9)	(242.0)
Ending Balance, Common Stock (in shares) at Dec. 31, 2022			71,412
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net earnings	49.0				49.0
Beginning Balance, Common Stock (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)
Ending Balance at Mar. 31, 2023	148.4		$ 0.8	786.4	(216.0)	(183.6)	(239.2)
Ending Balance, Common Stock (in shares) at Mar. 31, 2023			71,477
Beginning Balance, Common Stock (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]
Dividends to common shareholders	(65.9)
Ending Balance at Jun. 30, 2023	166.9		$ 0.8	768.4	(184.3)	(179.2)	(238.8)
Ending Balance, Common Stock (in shares) at Jun. 30, 2023			71,485
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Mandatory preferred stock dividends	0.0
Net earnings	120.8
Beginning Balance, Common Stock (in shares) at Dec. 31, 2022			71,412
Beginning Balance at Dec. 31, 2022	130.8		$ 0.8	802.9	(256.0)	(174.9)	(242.0)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Share-based payments	8.3			8.3
Activity under stock plans	0.0			(2.8)			2.8
Activity under stock plans (in shares)			65
Dividends to common shareholders	(22.0)			(22.0)	0.0
Other Comprehensive Income (Loss), Net of Tax	(8.7)					(8.7)
Ending Balance at Mar. 31, 2023	148.4		$ 0.8	786.4	(216.0)	(183.6)	(239.2)
Ending Balance, Common Stock (in shares) at Mar. 31, 2023			71,477
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net earnings	40.0				40.0
Share-based payments	4.3			4.3
Common stock purchased				15.0
Activity under stock plans				(0.3)	(0.1)		0.4
Activity under stock plans (in shares)			8
Dividends to common shareholders	(22.0)			(22.0)	0.0
Other Comprehensive Income (Loss), Net of Tax	4.4					4.4
Ending Balance at Jun. 30, 2023	166.9		$ 0.8	$ 768.4	(184.3)	$ (179.2)	$ (238.8)
Ending Balance, Common Stock (in shares) at Jun. 30, 2023			71,485
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Mandatory preferred stock dividends	0.0
Net earnings	31.8				31.8
Net earnings	$ 31.8				$ 31.8