Earnings Per Share (Details) - USD ($) shares in Millions, $ in Millions		3 Months Ended
		Apr. 30, 2020	Apr. 30, 2019
Earnings Per Share [Abstract]
Net (loss) earnings for basic and diluted EPS		$ (64.6)	$ 125.2
Weighted-average shares for basic EPS (shares)		121.2	121.4
Incremental shares based upon the assumed exercise of stock options and unvested restricted stock units (shares)	[1]	0.0	0.5
Weighted-average shares for diluted EPS (shares)		121.2	121.9
Antidilutive securities excluded from computation of earnings per share (shares)			1.7

[1] For the three months ended April 30, 2020, stock options and restricted stock units were excluded from the computation of diluted earnings per share due to the net loss incurred during the period. For the three months ended April 30, 2019, there were 1.7 million stock options and restricted stock units that were excluded from the computation of earnings per diluted share due to their antidilutive effect.