Selected Quarterly Financial Data (Unaudited) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended	12 Months Ended
Jan. 31, 2020	Oct. 31, 2019	Jul. 31, 2019	Apr. 30, 2019	Jan. 31, 2019	Oct. 31, 2018	Jul. 31, 2018	Apr. 30, 2018	Jan. 31, 2020	Jan. 31, 2019	Jan. 31, 2018
Quarterly Financial Information Disclosure [Abstract]
Revenue	$ 81,378	$ 76,370	$ 72,373	$ 68,708	$ 63,759	$ 58,613	$ 54,923	$ 50,988	$ 298,829	$ 228,283	$ 170,201
Gross profit	60,456	56,004	53,104	52,235	48,118	43,727	40,837	38,188	221,799	170,870	126,106
Loss from operations	(30,563)	(42,833)	(30,297)	(19,260)	(16,223)	(23,012)	(19,504)	(16,906)	(122,953)	(75,645)	(66,640)
Net loss	$ (30,577)	$ (42,717)	$ (29,291)	$ (18,959)	$ (15,460)	$ (22,940)	$ (19,396)	$ (17,041)	$ (121,544)	$ (74,837)	$ (66,565)
Net loss per share attributable to common stockholders, basic and diluted (in dollars per share)	$ (0.27)	$ (0.38)	$ (0.26)	$ (0.18)	$ (0.15)	$ (0.23)	$ (0.20)	$ (0.18)	$ (1.09)	$ (0.76)	$ (0.85)

The amount of net income or loss for the period per each share in instances when basic and diluted earnings per share are the same amount and reported as a single line item on the face of the financial statements. Basic earnings per share is the amount of net income or loss for the period per each share of common stock or unit outstanding during the reporting period. Diluted earnings per share includes the amount of net income or loss for the period available to each share of common stock or common unit outstanding during the reporting period and to each share or unit that would have been outstanding assuming the issuance of common shares or units for all dilutive potential common shares or units outstanding during the reporting period.

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