Stockholders' Equity - Accumulated Other Comprehensive Loss (Details) - USD ($) $ in Millions	Jan. 31, 2017	Jan. 31, 2016
Accumulated other comprehensive (loss) earnings, net of tax:
Foreign currency translation adjustments	$ (143.7)	$ (135.3)
Unrealized gain (loss) on marketable securities	0.8	(1.0)
Deferred hedging loss	(16.1)	(26.8)
Net unrealized loss on benefit plans	(97.2)	(115.0)
Accumulated other comprehensive (loss) gain, net of tax	$ (256.2)	$ (278.1)