CONSOLIDATED STATEMENTS OF COMPREHENSIVE EARNINGS - USD ($) $ in Millions	12 Months Ended
	Jan. 31, 2017	Jan. 31, 2016	Jan. 31, 2015
Statement of Comprehensive Income [Abstract]
Net earnings	$ 446.1	$ 463.9	$ 484.2
Other comprehensive earnings (loss), net of tax
Foreign currency translation adjustments	(8.4)	(59.0)	(93.1)
Unrealized gain (loss) on marketable securities	1.8	(2.9)	(0.8)
Unrealized gain (loss) on hedging instruments	10.7	(21.4)	1.2
Net unrealized gain (loss) on benefit plans	17.8	95.7	(139.2)
Other comprehensive earnings (loss), net of tax	21.9	12.4	(231.9)
Comprehensive earnings	$ 468.0	$ 476.3	$ 252.3