Stockholders' Equity - Accumulated Other Comprehensive Loss (Detail) - USD ($) $ in Millions	Jul. 31, 2017	Jan. 31, 2017	Jul. 31, 2016
Accumulated other comprehensive (loss) earnings, net of tax:
Foreign currency translation adjustments	$ (92.4)	$ (143.7)	$ (108.2)
Unrealized gain on marketable securities	0.5	0.8	1.0
Deferred hedging loss	(18.1)	(16.1)	(14.4)
Net unrealized loss on benefit plans	(93.2)	(97.2)	(110.6)
Accumulated other comprehensive loss, net of tax	$ (203.2)	$ (256.2)	$ (232.2)