CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY/(DEFICIT) - USD ($) shares in Thousands, $ in Millions	Total	Preferred Stock	Common Stock	Additional Paid-in Capital	Retained Earnings	Accumulated Other Comprehensive Loss	Treasury Stock
Dividends per common share (in dollars per share)	$ 0.30
Beginning Balance at Sep. 30, 2018	$ 24.5	$ 0.0	$ 0.6	$ 217.8	$ 177.3	$ (241.8)	$ (129.4)
Beginning Balance, Common Stock (in shares) at Sep. 30, 2018			59,608
Beginning Balance, Preferred Stock (in shares) at Sep. 30, 2018		0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net (loss)/earnings	70.8				70.8
Net earnings from discontinued operations	0.0
Share based payments	6.5			6.5
Activity under stock plans	(7.1)			(16.1)	(3.6)		12.6
Activity under stock plans (in shares)			290
Dividends to common shareholders ($0.30 per share)	(18.4)				(18.4)
Other comprehensive loss	(5.9)					(5.9)
Ending Balance at Dec. 31, 2018	70.4	$ 0.0	$ 0.6	208.2	226.1	(247.7)	(116.8)
Ending Balance, Common Stock (in shares) at Dec. 31, 2018			59,898
Ending Balance, Preferred Stock (in shares) at Dec. 31, 2018		0
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
Beginning Balance, Preferred Stock (in shares) at Sep. 30, 2019		2,156
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net (loss)/earnings	45.8				45.8
Net earnings from discontinued operations	0.3				0.3
Share based payments	7.2			7.2
Activity under stock plans	(9.4)			(24.9)	(1.1)		16.6
Activity under stock plans (in shares)			374
Dividends to common shareholders ($0.30 per share)	(21.4)				(21.4)
Dividends to common shareholders ($0.30 per share)	(4.0)				(4.0)
Other comprehensive loss	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
Ending Balance, Preferred Stock (in shares) at Dec. 31, 2019		2,156