Summary of Significant Accounting Policies - Narrative (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Oct. 31, 2019 USD ($)	Oct. 31, 2018 USD ($)	Oct. 31, 2019 USD ($) segment	Oct. 31, 2018 USD ($)	Feb. 01, 2019 USD ($)	Jan. 31, 2019 USD ($)
Lessee, Lease, Description [Line Items]
Number of operating segments | segment			1
Restricted cash	$ 1,051		$ 1,051			$ 2,620
Internal use software costs capitalized	2,200	$ 1,700	6,000	$ 2,500
Capitalized software development costs for software sold to customers	1,900	1,000
Capitalized software development costs for software sold to customers	4,300	1,000	4,300	1,000
Amortization expense of capitalized internal use software costs	600	$ 200	1,500	$ 600
Operating lease right-of-use assets	56,744		56,744
Operating lease liability	$ 59,709		$ 59,709
Accounting Standards Update 2016-02
Lessee, Lease, Description [Line Items]
Operating lease right-of-use assets					$ 53,400
Operating lease liability					55,300
Deferred rent					$ 1,900
Software
Lessee, Lease, Description [Line Items]
Software useful life			3 years
Letter of Credit Collateral
Lessee, Lease, Description [Line Items]
Restricted cash						1,800
Security Deposits
Lessee, Lease, Description [Line Items]
Restricted cash						$ 800