Segment Information - Reconciliation of Segments' Earnings from Operations to Company's Consolidated Earnings from Operations Before Income Taxes (Details) - USD ($) $ in Millions		3 Months Ended
		Apr. 30, 2020	Apr. 30, 2019
Segment Reporting [Abstract]
(Loss) earnings from operations for segments	[1]	$ (24.0)	$ 209.6
Unallocated corporate expenses		(52.7)	(48.7)
Interest expense and financing costs		(9.8)	(10.4)
Other income, net		25.4	1.0
Other operating expenses		(28.7)	0.0
(Loss) earnings from operations before income taxes		(89.8)	$ 151.5
Merger related expenses		16.7
Charitable contribution expense		$ 12.0

[1] Represents earnings from operations before (i) unallocated corporate expenses, (ii) Interest expense and financing costs and (iii) Other income, net.