Stockholders' Equity - Additions to and Reclassifications out of Accumulated Other Comprehensive (Loss) Earnings (Details) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Oct. 31, 2018	Oct. 31, 2017	Oct. 31, 2018	Oct. 31, 2017
Equity [Abstract]
Foreign currency translation adjustments		$ (25.0)	$ (10.0)	$ (83.8)	$ 40.8
Income tax (expense) benefit		(0.6)	0.0	(0.1)	0.5
Foreign currency translation adjustments, net of tax		(25.6)	(10.0)	(83.9)	41.3
Unrealized (loss) gain on marketable securities		0.0	(0.2)	0.0	0.5
Reclassification for gain included in net earnings	[1]	0.0	(1.4)	0.0	(2.2)
Income tax benefit		0.0	0.3	0.0	0.1
Unrealized loss on marketable securities, net of tax		0.0	(1.3)	0.0	(1.6)
Unrealized gain (loss) on hedging instruments		5.7	9.5	2.8	(5.7)
Reclassification adjustment for (gain) loss included in net earnings	[2]	(3.4)	(6.9)	(10.8)	5.7
Income tax (expense) benefit		(0.4)	(1.0)	2.2	(0.4)
Unrealized gain (loss) on hedging instruments, net of tax		1.9	1.6	(5.8)	(0.4)
Amortization of net loss included in net earnings	[3]	3.7	3.3	11.2	9.9
Amortization of prior service credit included in net earnings	[3]	(0.2)	(0.1)	(0.5)	(0.3)
Income tax expense		(0.8)	(1.2)	(2.5)	(3.6)
Unrealized gain on benefit plans		2.7	2.0	8.2	6.0
Total other comprehensive (loss) earnings, net of tax		$ (21.0)	$ (7.7)	$ (81.5)	$ 45.3

[1] These gains were reclassified into Other expense, net.

[2] These (gains) losses are reclassified into Cost of Sales, Interest expense and financing costs and Other expense, net (see "Note 8. Hedging Instruments" for additional details).

[3] These accumulated other comprehensive income components are included in the computation of net periodic pension costs (see "Note 12. Employee Benefit Plans" for additional details).