Leases (Additional Information) (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
	Jul. 31, 2018	Jul. 31, 2019	Jul. 31, 2018
Lessee, Lease, Description [Line Items]
Variable lease payments		$ 6.4
Weighted average remaining lease term (in years)		6 years
Weighted average discount rate (in percentage)		3.81%
Operating lease minimum payments, executed leases that have not commenced		$ 156.4
Rent expense	$ 15.4		$ 30.5
Minimum
Lessee, Lease, Description [Line Items]
Remaining lease term (in years)		1 year
Lease renewal term (in years)		1 year
Optional termination period (in years)		1 year
Maximum
Lessee, Lease, Description [Line Items]
Remaining lease term (in years)		71 years
Lease renewal term (in years)		10 years
Optional termination period (in years)		11 years