Net Income Per Share Attributable to Common Stockholders - Schedule of Computation of Basic and Diluted Net Income Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jul. 31, 2020	Jul. 31, 2019	Jul. 31, 2020	Jul. 31, 2019
Numerator:
Net income (loss)	$ 185,989	$ 5,541	$ 213,064	$ 7,755
Net income attributable to common stockholders	$ 185,742	$ 5,521	$ 212,759	$ 4,961
Denominator:
Weighted-average shares used in computing net income per share attributable to common stockholders, basic (in shares)	282,850,805	271,813,141	281,394,901	192,130,510
Weighted-average shares used in computing net income per share attributable to common stockholders, diluted (in shares)	297,162,309	292,185,665	296,408,229	215,774,619
Net income per share attributable to common stockholders, basic (in dollars per share)	$ 0.66	$ 0.02	$ 0.76	$ 0.03
Net income per share attributable to common stockholders, diluted (in dollars per share)	$ 0.63	$ 0.02	$ 0.72	$ 0.02
Class A Common Stock
Numerator:
Net income (loss)	$ 122,474	$ 751	$ 125,297	$ 592
Less: undistributed earnings attributable to participating securities	0	0	0	0
Net income attributable to common stockholders	122,474	751	125,297	592
Reallocation of net income attributable to common stockholders	(4,343)	(50)	(4,824)	(64)
Net income (loss) attributable to common stockholders, diluted	$ 118,131	$ 701	$ 120,473	$ 528
Denominator:
Weighted-average shares used in computing net income per share attributable to common stockholders, basic (in shares)	186,505,788	36,950,454	165,718,132	22,908,474
Weighted-average shares used in computing net income per share attributable to common stockholders, diluted (in shares)	188,994,684	37,120,969	167,839,216	22,977,562
Net income per share attributable to common stockholders, basic (in dollars per share)	$ 0.66	$ 0.02	$ 0.76	$ 0.03
Net income per share attributable to common stockholders, diluted (in dollars per share)	$ 0.63	$ 0.02	$ 0.72	$ 0.02
Class B Common Stock
Numerator:
Net income (loss)	$ 63,515	$ 4,790	$ 87,767	$ 7,163
Less: undistributed earnings attributable to participating securities	(247)	(20)	(305)	(2,794)
Net income attributable to common stockholders	63,268	4,770	87,462	4,369
Reallocation of net income attributable to common stockholders	4,343	50	4,824	64
Net income (loss) attributable to common stockholders, diluted	$ 67,611	$ 4,820	$ 92,286	$ 4,433
Denominator:
Weighted-average shares used in computing net income per share attributable to common stockholders, basic (in shares)	96,345,017	234,862,687	115,676,769	169,222,036
Weighted-average shares used in computing net income per share attributable to common stockholders, diluted (in shares)	108,167,625	255,064,696	128,569,013	192,797,057
Net income per share attributable to common stockholders, basic (in dollars per share)	$ 0.66	$ 0.02	$ 0.76	$ 0.03
Net income per share attributable to common stockholders, diluted (in dollars per share)	$ 0.63	$ 0.02	$ 0.72	$ 0.02