Net Earnings Per Common Share (Computations of Basic and Diluted Earnings Per Share) (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended				6 Months Ended
	Jul. 31, 2019	Apr. 30, 2019	Jul. 31, 2018	Apr. 30, 2018	Jul. 31, 2019	Jul. 31, 2018	Sep. 14, 2018
Net Earnings Per Common Share
Net (loss) earnings	$ 3.5	$ (5.0)	$ 13.6	$ 5.8	$ (1.5)	$ 19.4
Basic weighted average common shares	22,300,000		20,100,000		21,800,000	20,100,000
Diluted weighted average common shares	22,300,000		20,100,000		21,800,000	20,100,000
Basic net earnings (loss) per common share (in dollars per share)	$ 0.16		$ 0.68		$ (0.07)	$ 0.97
Diluted net earnings (loss) per common share (in dollars per share)	$ 0.16		$ 0.68		$ (0.07)	$ 0.97
Number of shares received for each share of former parent entity							0.4
Number of shares of former parent used in share distribution calculation							1.0