Stockholders' Equity - Additions to and Reclassifications out of Accumulated Other Comprehensive (Loss) Earnings (Detail) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Jul. 31, 2017	Jul. 31, 2016	Jul. 31, 2017	Jul. 31, 2016
Equity [Abstract]
Foreign currency translation adjustments		$ 38.5	$ (22.8)	$ 50.9	$ 36.0
Income tax benefit (expense)		0.7	(1.8)	0.4	(8.9)
Foreign currency translation adjustments		39.2	(24.6)	51.3	27.1
Unrealized gain on marketable securities		0.3	1.3	0.7	3.0
Reclassification for gain included in net earnings a	[1]	(0.8)	0.0	(0.8)	0.0
Income tax benefit (expense)		0.1	(0.4)	(0.2)	(1.0)
Unrealized (loss) gain on marketable securities		(0.4)	0.9	(0.3)	2.0
Unrealized (loss) gain on hedging instruments		(4.9)	9.9	(15.2)	17.9
Reclassification adjustment for loss included in net earnings b	[2]	3.6	2.7	12.5	2.2
Income tax benefit (expense)		0.3	(4.5)	0.7	(7.7)
Unrealized (loss) gain on hedging instruments		(1.0)	8.1	(2.0)	12.4
Amortization of net loss included in net earnings	[3]	3.0	3.4	6.6	7.3
Amortization of prior service credit included in net earnings	[3]	(0.1)	(0.2)	(0.1)	(0.4)
Income tax expense		(1.1)	(1.2)	(2.5)	(2.5)
Net unrealized gain on benefit plans		1.8	2.0	4.0	4.4
Other comprehensive earnings (loss), net of tax		$ 39.6	$ (13.6)	$ 53.0	$ 45.9

[1] These gains are reclassified into Interest and other expenses, net.

[2] These losses are reclassified into Cost of sales and Interest and other expenses, net (see "Note 7. Hedging Instruments" for additional details).

[3] These accumulated other comprehensive income components are included in the computation of net periodic pension costs (see "Note 11. Employee Benefit Plans" for additional details).