Earnings per Common Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Millions	3 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Dec. 31, 2017
Earnings Per Share [Abstract]
Net Income (Loss) Attributable to Parent	$ 42.2		$ 88.3
Average Common Shares Outstanding - Basic (in shares)	67,053		65,906
Add potential effect of exercise of stock options and other unvested equity awards (in shares)	672		1,526
Average shares outstanding - Diluted (in shares)	67,725		67,432
Net income attributable to common shareholders per common share - Basic (usd per share)		$ 0.63	$ 1.34
Net income attributable to common shareholders per common share - Diluted (usd per share)		$ 0.62	$ 1.31
Shares with anti-dilutive effect excluded from the computation of Diluted EPS (in shares)	486		233