Net Income Per Common Share Computations (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Earnings Per Share [Abstract]
Net income from continuing operations	$ 11.9	$ 14.1
Net (loss) income from discontinued operations	(0.3)	167.9
Numerator for basic net income per common share	11.6	182.0
Numerator for diluted net income from continuing operations per common share	11.9	14.1
Numerator for diluted net income per common share:	$ 11.6	$ 182.0
Earnings Per Share, Basic and Diluted [Abstract]
Basic (in shares)	40.4	43.3
Plus dilutive effect of stock awards (in shares)	0.2	0.2
Diluted (in shares)	40.6	43.5
Basic
Continuing operations (in dollars per share)	$ 0.30	$ 0.33
Discontinued operations (in dollars per share)	(0.01)	3.87
Net income per common share data - basic (in dollars per share)	0.29	4.20
Diluted
Continuing operations (in dollars per share)	0.30	0.32
Discontinued operations (in dollars per share)	(0.01)	3.86
Net income per common share data - diluted (in dollars per share)	$ 0.29	$ 4.18