Net Earnings Per Common Share (Computations of Basic and Diluted Earnings Per Share) (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Jul. 31, 2017	Jul. 31, 2016	Jul. 31, 2017	Jul. 31, 2016
Net Earnings Per Common Share
Net earnings	$ 20.7	$ 8.0	$ 39.1	$ 10.5
Basic weighted average common shares (in millions)	50.9	51.9	51.0	51.9
Effect of dilutive securities - dilutive securities	0.8	0.3	0.7	0.3
Diluted weighted average common shares (in millions)	51.7	52.2	51.7	52.2
Basic net earnings per common share	$ 0.41	$ 0.15	$ 0.77	$ 0.20
Diluted net earnings per common share	$ 0.40	$ 0.15	$ 0.76	$ 0.20