Goodwill and Acquired Intangible Assets, Net - Additional Information (Details) - USD ($) $ in Millions	12 Months Ended
	Jan. 31, 2020	Jan. 31, 2019	Jan. 31, 2018
Acquired Finite-Lived Intangible Assets [Line Items]
Amortization of intangible assets	$ 10.1	$ 2.3	$ 0.9
Developed technology
Acquired Finite-Lived Intangible Assets [Line Items]
Weighted average useful life	4 years 3 months 18 days
Domain name
Acquired Finite-Lived Intangible Assets [Line Items]
Weighted average useful life	2 months 12 days
Customer relationships
Acquired Finite-Lived Intangible Assets [Line Items]
Weighted average useful life	3 years 9 months 18 days