Net Income (Loss) Per Share Attributable to Common Stockholders - Schedule of Computation of Basic and Diluted Net Income (Loss) Per Share (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
Earnings Per Share, Basic [Abstract]
Net income (loss)									$ 25,305	$ 7,584	$ (3,822)
Distributed Earnings									0	0	4,405
Less: undistributed earnings attributable to participating securities									3,555	7,584	0
Net income (loss) attributable to common stockholders	$ 15,313	$ 2,207	$ 5,521	$ 198	$ 1,196	$ (598)	$ 496	$ (1,340)	$ 21,750	$ 0	$ (8,227)
Earnings Per Share, Diluted [Abstract]
Weighted-average shares used in computing net income (loss) per share attributable to common stockholders, basic (in shares)									233,641,336	84,483,094	78,119,865
Weighted-average shares used in computing net income (loss) per share attributable to common stockholders, diluted (in shares)									254,298,014	116,005,681	78,119,865
Net income (loss) per share attributable to common stockholders, basic (in dollars per share)	$ 0.06	$ 0.01	$ 0.02	$ 0.00	$ 0.01	$ (0.01)	$ 0.01	$ (0.02)	$ 0.09	$ 0.00	$ (0.11)
Net income (loss) per share attributable to common stockholders, diluted (in dollars per share)	$ 0.05	$ 0.01	$ 0.02	$ 0.00	$ 0.01	$ (0.01)	$ 0.00	$ (0.02)	$ 0.09	$ 0.00	$ (0.11)
Class A Common Stock
Earnings Per Share, Basic [Abstract]
Net income (loss)									$ 5,450	$ 0	$ 0
Distributed Earnings									0	0	0
Less: undistributed earnings attributable to participating securities									0	0	0
Net income (loss) attributable to common stockholders									5,450	0	0
Reallocation of net income (loss) attributable to common stockholders									(439)	0	0
Net income (loss) attributable to common stockholders, diluted									$ 5,011	$ 0	$ 0
Earnings Per Share, Diluted [Abstract]
Weighted-average shares used in computing net income (loss) per share attributable to common stockholders, basic (in shares)									58,541,269	0	0
Weighted-average shares used in computing net income (loss) per share attributable to common stockholders, diluted (in shares)									58,583,874	0	0
Net income (loss) per share attributable to common stockholders, basic (in dollars per share)									$ 0.09	$ 0	$ 0
Net income (loss) per share attributable to common stockholders, diluted (in dollars per share)									$ 0.09	$ 0	$ 0
Class B Common Stock
Earnings Per Share, Basic [Abstract]
Net income (loss)									$ 19,855	$ 7,584	$ (3,822)
Distributed Earnings									0	0	4,405
Less: undistributed earnings attributable to participating securities									3,555	7,584	0
Net income (loss) attributable to common stockholders									16,300	0	(8,227)
Reallocation of net income (loss) attributable to common stockholders									439	0	0
Net income (loss) attributable to common stockholders, diluted									$ 16,739	$ 0	$ (8,227)
Earnings Per Share, Diluted [Abstract]
Weighted-average shares used in computing net income (loss) per share attributable to common stockholders, basic (in shares)									175,100,067	84,483,094	78,119,865
Weighted-average shares used in computing net income (loss) per share attributable to common stockholders, diluted (in shares)									195,714,140	116,005,681	78,119,865
Net income (loss) per share attributable to common stockholders, basic (in dollars per share)									$ 0.09	$ 0.00	$ (0.11)
Net income (loss) per share attributable to common stockholders, diluted (in dollars per share)									$ 0.09	$ 0.00	$ (0.11)