Condensed Consolidated Statements of Stockholders' Equity (Unaudited) - USD ($) $ in Thousands	Total	Class A & B common stock	Additional paid-in capital	Retained earnings	Accumulated other comprehensive income
Beginning balance (in shares) at Jan. 31, 2020		149,095,583
Beginning balance at Jan. 31, 2020	$ 1,665,594	$ 1	$ 745,475	$ 919,658	$ 460
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon exercise of stock options (in shares)		645,515
Issuance of common stock upon exercise of stock options	10,279	$ 1	10,278
Issuance of common stock upon vesting of restricted stock units (in shares)		288,949
Issuance of common stock upon vesting of restricted stock units	0
Stock-based compensation expense	36,907		36,907
Change in other comprehensive income (loss)	1,686				1,686
Net income	86,570			86,570
Ending balance (in shares) at Apr. 30, 2020		150,030,047
Ending balance at Apr. 30, 2020	1,801,036	$ 2	792,660	1,006,228	2,146
Beginning balance (in shares) at Jan. 31, 2021		152,056,808
Beginning balance at Jan. 31, 2021	$ 2,266,320	$ 2	965,670	1,299,656	992
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock upon exercise of stock options (in shares)	485,037	485,037
Issuance of common stock upon exercise of stock options	$ 17,600		17,600
Issuance of common stock upon vesting of restricted stock units (in shares)		258,511
Issuance of common stock upon vesting of restricted stock units	0
Stock-based compensation expense	48,793		48,793
Change in other comprehensive income (loss)	(3,296)				(3,296)
Net income	115,567			115,567
Ending balance (in shares) at Apr. 30, 2021		152,800,356
Ending balance at Apr. 30, 2021	$ 2,444,984	$ 2	$ 1,032,063	$ 1,415,223	$ (2,304)