Leases - Narrative (Details) - USD ($) $ in Millions	3 Months Ended
	Apr. 30, 2020	Apr. 30, 2019	Jan. 31, 2020
Leases [Abstract]
Weighted average remaining lease term	7 years 8 months 12 days		7 years 10 months 24 days
Weighted average discount rate	5.60%		5.70%
Cash payments included in the measurement of operating lease liabilities	$ 7.1	$ 2.4
Undiscounted future payments under operating leases that have not yet commenced	$ 4.7
Operating lease terms for leases that have not yet commenced	4 years