CONSOLIDATED STATEMENTS OF COMPREHENSIVE EARNINGS - USD ($) $ in Millions	12 Months Ended
	Jan. 31, 2018	Jan. 31, 2017	Jan. 31, 2016
Statement of Comprehensive Income [Abstract]
Net earnings	$ 370.1	$ 446.1	$ 463.9
Other comprehensive earnings (loss), net of tax
Foreign currency translation adjustments	95.7	(8.4)	(59.0)
Unrealized (loss) gain on marketable securities	(2.6)	1.8	(2.9)
Unrealized (loss) gain on hedging instruments	(6.8)	10.7	(21.4)
Unrealized gain on benefit plans	31.9	17.8	95.7
Other comprehensive earnings, net of tax	118.2	21.9	12.4
Comprehensive earnings	$ 488.3	$ 468.0	$ 476.3