Earnings per Common Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2017	Mar. 31, 2016
Earnings Per Share [Abstract]
Net Income (Loss) Attributable to Parent	$ 34.4	$ 22.3	$ 58.2	$ 27.1
Average Common Shares Outstanding - Basic (in shares)	65,462	65,331	65,473	65,264
Add potential effect of exercise of stock options and other unvested equity awards (in shares)	1,670	1,051	1,584	1,100
Average shares outstanding - Diluted (in shares)	67,132	66,382	67,057	66,364
Net income attributable to common shareholders per common share - Basic (usd per share)	$ 0.52	$ 0.34	$ 0.89	$ 0.41
Net income attributable to common shareholders per common share - Diluted (usd per share)	$ 0.51	$ 0.33	$ 0.87	$ 0.41
Shares with anti-dilutive effect excluded from the computation of Diluted EPS (in shares)	348	625	500	568