Condensed Consolidated Statement of Stockholders' Equity - 3 months ended Dec. 31, 2017 - USD ($) $ in Millions	Total	Common Stock [Member]	Treasury Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Loss [Member]
Balances as of beginning of period at Sep. 30, 2017	$ 449.9	$ 0.2	$ (46.3)	$ 259.0	$ 261.5	$ (24.5)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	(6.9)				(6.9)
Other comprehensive loss	(2.2)					(2.2)
Exercise of stock options	0.8			0.8
Share-based Compensation	1.6			1.6
Balances as of end of period at Dec. 31, 2017	$ 443.2	$ 0.2	$ (46.3)	$ 261.4	$ 254.6	$ (26.7)