Stockholders' Equity - Additions to and Reclassifications out of Accumulated Other Comprehensive (Loss) Earnings (Details) - USD ($) $ in Millions	12 Months Ended
	Jan. 31, 2019	Jan. 31, 2018	Jan. 31, 2017
Equity [Abstract]
Foreign currency translation adjustments	$ (62.9)	$ 97.9	$ 8.3
Income tax benefit (expense)	2.7	(2.2)	(16.7)
Foreign currency translation adjustments, net of tax	(60.2)	95.7	(8.4)
Unrealized gain on marketable securities	0.0	0.2	2.7
Reclassification for gain included in net earnings	0.0	(3.5)	0.0
Income tax benefit (expense)	0.0	0.7	(0.9)
Unrealized (loss) gain on marketable securities, net of tax	0.0	(2.6)	1.8
Unrealized (loss) gain on hedging instruments	(1.1)	(21.0)	12.1
Reclassification adjustment for loss (gain) included in net earnings	(1.2)	13.0	4.9
Income tax benefit (expense)	0.7	1.2	(6.3)
Unrealized (loss) gain on hedging instruments, net of tax	(1.6)	(6.8)	10.7
Net actuarial (loss) gain	(24.2)	30.6	14.1
Amortization of net loss included in net earnings	15.1	13.3	14.7
Amortization of prior service credit included in net earnings	0.6	0.5	0.7
Income tax benefit (expense)	2.9	(11.5)	(10.3)
Net unrealized (loss) gain on benefit plans, net of tax	(6.8)	31.9	17.8
Total other comprehensive (loss) earnings, net of tax	$ (68.6)	$ 118.2	$ 21.9