CONDENSED CONSOLIDATED STATEMENTS OF STOCKHOLDERS’ EQUITY - USD ($) $ in Thousands	Total	Class A and Class B Common Stock	Additional Paid-In Capital	Treasury Stock	Accumulated Other Comprehensive Income (Loss)	Accumulated Deficit	Cumulative Effect, Period of Adoption, Adjustment	Cumulative Effect, Period of Adoption, Adjustment Accumulated Deficit
Beginning balance (in shares) at Jan. 31, 2019		54,321,810
Beginning balance at Jan. 31, 2019	$ 264,566	$ 54	$ 754,612	$ (1,319)	$ (174)	$ (488,607)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock option exercises (in shares)		831,901
Stock option exercises	6,438	$ 1	6,437
Repurchase of early exercised options (in shares)		(3,981)
Vesting of early exercised stock options	127		127
Vesting of restricted stock units (in shares)		126,346
Stock-based compensation	14,009		14,009
Unrealized gain on available-for-sale securities	58				58
Foreign currency translation adjustment	13				13
Net loss	(33,240)					(33,240)
Ending balance (in shares) at Apr. 30, 2019		55,276,076
Ending balance at Apr. 30, 2019	247,868	$ 55	775,185	(1,319)	(103)	(525,950)	$ (4,103)	$ (4,103)
Beginning balance (in shares) at Jan. 31, 2020		57,382,543
Beginning balance at Jan. 31, 2020	$ 82,858	$ 57	752,127	(1,319)	225	(668,232)	$ (227)	$ (227)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock option exercises (in shares)	373,394	373,394
Stock option exercises	$ 2,995	$ 1	2,994
Repurchase of early exercised options (in shares)		(79)
Vesting of early exercised stock options	42		42
Vesting of restricted stock units (in shares)		241,569
Stock-based compensation	30,567		30,567
Conversion of 2024 convertible senior notes (in shares)		8
Unrealized gain on available-for-sale securities	848				848
Foreign currency translation adjustment	(75)				(75)
Net loss	(53,967)					(53,967)
Ending balance (in shares) at Apr. 30, 2020		57,997,435
Ending balance at Apr. 30, 2020	$ 63,041	$ 58	$ 785,730	$ (1,319)	$ 998	$ (722,426)