Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Total	Preferred Stock Convertible preferred stock	Common Stock	Common Stock Common Class A	Common Stock Common Class B	Additional Paid-In Capital	Accumulated Other Comprehensive Loss	Accumulated Deficit
Beginning balance at Jan. 31, 2019	$ (6,558)	$ 72	$ 0	$ 30	$ 0	$ 363,076	$ (1,096)	$ (368,640)
Beginning balance (in shares) at Jan. 31, 2019		72,482,609	0	29,755,883	3,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise of employee stock options	5,268			$ 1		5,267
Exercise of employee stock options (in shares)				1,370,818
Issuance of Series F preferred shares, net of issuance costs	69,848	$ 5				69,843
Issuance of Series F preferred shares, net of issuance costs (in shares)		4,666,666
Vesting of early exercised stock options	207					207
Stock-based compensation	7,962					7,962
Other comprehensive loss	(401)						(401)
Net loss	(2,559)							(2,559)
Ending balance at Apr. 30, 2019	73,767	$ 77	$ 0	$ 31	$ 0	446,355	(1,497)	(371,199)
Ending balance (in shares) at Apr. 30, 2019		77,149,275	0	31,126,701	3,000
Beginning balance at Jan. 31, 2020	397,796	$ 0	$ 132	$ 0	$ 0	878,843	(206)	(480,973)
Beginning balance (in shares) at Jan. 31, 2020		0	132,346,402	0	0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise of employee stock options	$ 18,934		$ 6			18,928
Exercise of employee stock options (in shares)	5,184,632		5,184,632
Release of restricted stock units (in shares)			1,671,652
Issuance of shares from share purchase plan	$ 10,267		$ 1			10,266
Issuance of shares from share purchase plan (in shares)			591,732
Stock-based compensation	31,804					31,804
Other comprehensive loss	(2,751)						(2,751)
Net loss	(32,529)							(32,529)
Ending balance at Apr. 30, 2020	$ 423,521	$ 0	$ 139	$ 0	$ 0	$ 939,841	$ (2,957)	$ (513,502)
Ending balance (in shares) at Apr. 30, 2020		0	139,794,418	0	0