Earnings per Common Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Millions	3 Months Ended		9 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Earnings Per Share [Abstract]
Net Income (Loss) Attributable to Parent	$ 93.9	$ 32.6	$ 180.6	$ 124.3
Net income attributable to common shareholders per common share - Basic (usd per share)	$ 1.41	$ 0.49	$ 2.71	$ 1.86
Net income attributable to common shareholders per common share - Diluted (usd per share)	$ 1.40	$ 0.48	$ 2.68	$ 1.84
Average Common Shares Outstanding - Basic (in shares)	66,558	66,777	66,660	66,822
Add potential effect of exercise of stock options and other unvested equity awards (in shares)	625	669	632	662
Average shares outstanding - Diluted (in shares)	67,183	67,446	67,292	67,484
Shares with anti-dilutive effect excluded from the computation of Diluted EPS (in shares)	291	258	298	299