Equity (Details) $ / shares in Units, $ in Thousands		1 Months Ended	12 Months Ended
	Mar. 20, 2019 USD ($) $ / shares shares	Apr. 30, 2017 USD ($) $ / shares shares	Jan. 31, 2020 USD ($) vote $ / shares shares	Jan. 31, 2019 USD ($) $ / shares shares	Jan. 31, 2018 USD ($) shares
Class of Stock [Line Items]
Proceeds from common stock offering, net of underwriting discounts and commissions | $			$ 147,000	$ 0	$ 0
Issuance costs | $	$ 500
Change in fair value of convertible preferred stock warrant liability | $		$ 500	$ 0	$ 0	491
Conversion of preferred stock warrant | $		$ 1,400			$ 1,435
Preferred stock shares authorized (in shares)		50,000,000	50,000,000	50,000,000
Preferred stock par value (in dollars per share) | $ / shares		$ 0.001	$ 0.001	$ 0.001
Preferred stock shares issued (in shares)			0	0
Preferred stock shares outstanding (in shares)			0	0
Common stock shares authorized (in shares)			500,000,000	500,000,000
Common stock par value (in dollars per share) | $ / shares			$ 0.001	$ 0.001
Common stock number of votes per share | vote			1
Treasury stock (in shares)			6,505,334	6,505,334
Treasury stock | $			$ 11,905	$ 11,905
Common Stock
Class of Stock [Line Items]
Conversion of preferred stock (in shares)		43,594,753
Common Stock
Class of Stock [Line Items]
Convertible preferred stock automatically converted into warrants exercisable (in shares)		110,937
Common Stock
Class of Stock [Line Items]
Common stock offering, net of issuance costs (in shares)	7,000,000		7,000,000		12,075,000
Sale of stock, price per share (in dollars per share) | $ / shares	$ 21.50
Proceeds from common stock offering, net of underwriting discounts and commissions | $	$ 147,000
Conversion of preferred stock (in shares)					43,594,000