Leases - Lease Cost in Statements of Earnings (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
	Jul. 31, 2019	Jul. 31, 2019
Leases [Abstract]
Fixed operating lease expense	$ 77.7	$ 155.0
Variable operating lease expense	35.8	70.4
Sublease income	(1.2)	(2.4)
Net lease expense	$ 112.3	$ 223.0