CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY/(DEFICIT) - USD ($) $ in Millions	Total	Preferred Stock	Common Stock	Additional Paid-in Capital	Retained Earnings	Accumulated Other Comprehensive (Loss)/Income	Treasury Stock
Beginning Balance at Sep. 30, 2019	$ 543.8	$ 0.0	$ 0.7	$ 870.3	$ 129.5	$ (298.3)	$ (158.4)
Beginning Balance, Common Stock (in shares) at Sep. 30, 2019			68,902,000
Beginning Balance, Preferred Stock (in shares) at Sep. 30, 2019		2,156,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net (loss)/earnings	45.8				45.8
Net loss from discontinued operations	0.3				0.3
APIC, Share-based Payment Arrangement, Increase for Cost Recognition	7.2			7.2
Activity under stock plans	(9.4)			(24.9)	(1.1)		16.6
Activity under stock plans (in shares)			374,000
Dividends to common shareholders	(21.4)				(21.4)
Dividends to preferred shareholders	(4.0)				(4.0)
Other Comprehensive Income (Loss), Net of Tax	25.2					25.2
Ending Balance at Dec. 31, 2019	$ 587.5	$ 0.0	$ 0.7	852.6	149.1	(273.1)	(141.8)
Ending Balance, Common Stock (in shares) at Dec. 31, 2019			69,276,000
Ending Balance, Preferred Stock (in shares) at Dec. 31, 2019		2,156,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Dividends per common share (in dollars per share)	$ 0.30
Preferred stock dividend declared (in dollars per share)	$ 1.83
Beginning Balance at Sep. 30, 2019	$ 543.8	$ 0.0	$ 0.7	870.3	129.5	(298.3)	(158.4)
Beginning Balance, Common Stock (in shares) at Sep. 30, 2019			68,902,000
Beginning Balance, Preferred Stock (in shares) at Sep. 30, 2019		2,156,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss from discontinued operations	(131.1)
Dividends to common shareholders	(42.8)
Ending Balance at Mar. 31, 2020	373.7	$ 0.0	$ 0.7	853.9	5.8	(307.1)	(179.6)
Ending Balance, Common Stock (in shares) at Mar. 31, 2020			68,457,000
Ending Balance, Preferred Stock (in shares) at Mar. 31, 2020		2,156,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Mandatory preferred stock dividends	(8.1)
Share-based compensation expense	15.9
Beginning Balance at Dec. 31, 2019	587.5	$ 0.0	$ 0.7	852.6	149.1	(273.1)	(141.8)
Beginning Balance, Common Stock (in shares) at Dec. 31, 2019			69,276,000
Beginning Balance, Preferred Stock (in shares) at Dec. 31, 2019		2,156,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net (loss)/earnings	13.7				13.7
Net loss from discontinued operations	(131.4)				(131.4)
APIC, Share-based Payment Arrangement, Increase for Cost Recognition	8.7			8.7
Common stock purchased	$ (45.0)						(45.0)
Common stock purchased (in shares)	(980,136)		(980,000)
Activity under stock plans	$ (0.3)			(1.7)	(0.1)		1.5
Deferred compensation plan	0.0			(5.7)			5.7
Deferred compensation plan (in shares)			125,000
Activity under stock plans (in shares)			36,000
Dividends to common shareholders	(21.4)				(21.4)
Dividends to preferred shareholders	(4.1)				(4.1)
Other Comprehensive Income (Loss), Net of Tax	(34.0)					(34.0)
Ending Balance at Mar. 31, 2020	373.7	$ 0.0	$ 0.7	853.9	5.8	(307.1)	(179.6)
Ending Balance, Common Stock (in shares) at Mar. 31, 2020			68,457,000
Ending Balance, Preferred Stock (in shares) at Mar. 31, 2020		2,156,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Mandatory preferred stock dividends	$ (4.1)
Dividends per common share (in dollars per share)	$ 0.30
Preferred stock dividend declared (in dollars per share)	$ 1.875
Share-based compensation expense	$ 8.7
Beginning Balance at Sep. 30, 2020	309.1	$ 0.0	$ 0.7	859.2	(66.2)	(307.7)	(176.9)
Beginning Balance, Common Stock (in shares) at Sep. 30, 2020			68,518,000
Beginning Balance, Preferred Stock (in shares) at Sep. 30, 2020		2,156,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net (loss)/earnings	67.1				67.1
Common stock purchased	(21.3)						(21.3)
Common stock purchased (in shares)			(500,000)
Activity under stock plans	(6.7)			(20.6)	(0.9)		14.8
Deferred compensation plan	0.0			(1.0)			1.0
Deferred compensation plan (in shares)			22,000
Activity under stock plans (in shares)			314,000
Dividends to common shareholders	(21.0)				(21.0)
Dividends to preferred shareholders	(4.0)				(4.0)
Other Comprehensive Income (Loss), Net of Tax	2.4					2.4
Ending Balance at Dec. 31, 2020	$ 329.6	$ 0.0	$ 0.7	841.6	(25.0)	(305.3)	(182.4)
Ending Balance, Common Stock (in shares) at Dec. 31, 2020			68,354,000
Ending Balance, Preferred Stock (in shares) at Dec. 31, 2020		2,156,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Dividends per common share (in dollars per share)	$ 0.30
Preferred stock dividend declared (in dollars per share)	$ 1.875
Share-based compensation expense	$ 4.0			4.0
Beginning Balance at Sep. 30, 2020	309.1	$ 0.0	$ 0.7	859.2	(66.2)	(307.7)	(176.9)
Beginning Balance, Common Stock (in shares) at Sep. 30, 2020			68,518,000
Beginning Balance, Preferred Stock (in shares) at Sep. 30, 2020		2,156,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss from discontinued operations	0.0
Dividends to common shareholders	(41.9)
Ending Balance at Mar. 31, 2021	344.4	$ 0.0	$ 0.7	846.4	(60.2)	(260.7)	(181.8)
Ending Balance, Common Stock (in shares) at Mar. 31, 2021			68,366,000
Ending Balance, Preferred Stock (in shares) at Mar. 31, 2021		2,156,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Mandatory preferred stock dividends	(8.1)
Share-based compensation expense	9.4
Beginning Balance at Dec. 31, 2020	329.6	$ 0.0	$ 0.7	841.6	(25.0)	(305.3)	(182.4)
Beginning Balance, Common Stock (in shares) at Dec. 31, 2020			68,354,000
Beginning Balance, Preferred Stock (in shares) at Dec. 31, 2020		2,156,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net (loss)/earnings	(10.2)				(10.2)
Net loss from discontinued operations					0.0
Common stock purchased	$ (21.3)
Common stock purchased (in shares)	(500,000)
Activity under stock plans				(0.6)			0.6
Deferred compensation plan	$ 0.1
Activity under stock plans (in shares)			12,000
Dividends to common shareholders	(20.9)				(20.9)
Dividends to preferred shareholders	(4.1)				(4.1)
Other Comprehensive Income (Loss), Net of Tax	44.6					44.6
Ending Balance at Mar. 31, 2021	344.4	$ 0.0	$ 0.7	846.4	$ (60.2)	$ (260.7)	$ (181.8)
Ending Balance, Common Stock (in shares) at Mar. 31, 2021			68,366,000
Ending Balance, Preferred Stock (in shares) at Mar. 31, 2021		2,156,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Mandatory preferred stock dividends	$ (4.1)
Preferred stock dividend declared (in dollars per share)	$ 1.88
Share-based compensation expense	$ 5.4			$ 5.4