Leases (Additional Information) (Details) - USD ($) $ in Millions	3 Months Ended
	Apr. 30, 2019	Apr. 30, 2018
Lessee, Lease, Description [Line Items]
Variable lease payments	$ 3.0
Weighted average remaining lease term	6 years 2 months 12 days
Weighted average discount rate	3.85%
Operating lease minimum payments, executed leases that have not commenced	$ 25.8
Rent expense		$ 15.1
Minimum
Lessee, Lease, Description [Line Items]
Remaining lease term	1 year
Lease renewal term	1 year
Optional termination period	1 year
Maximum
Lessee, Lease, Description [Line Items]
Remaining lease term	71 years
Lease renewal term	10 years
Optional termination period	11 years