Net Income per Share - Numerators and Denominators of the Basic and Diluted EPS Computations for Common Stock (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Apr. 30, 2021	Apr. 30, 2020
Schedule Of Earnings Per Share Basic And Diluted [Line Items]
Weighted average shares used in computing net income per share, basic (in shares)	152,444	149,541
Net income per share, basic (in usd per share)	$ 0.76	$ 0.58
Reallocation as a result of conversion of Class B to Class A common stock:
Weighted average shares used in computing net income per share, diluted (in shares)	162,213	159,474
Net income per share, diluted (in usd per share)	$ 0.71	$ 0.54
Class A common stock
Schedule Of Earnings Per Share Basic And Diluted [Line Items]
Net income, basic	$ 104,319	$ 77,777
Weighted average shares used in computing net income per share, basic (in shares)	137,607	134,353
Net income per share, basic (in usd per share)	$ 0.76	$ 0.58
Reallocation as a result of conversion of Class B to Class A common stock:
Net income, basic	$ 11,248	$ 8,793
Reallocation of net income to Class B common stock	0	0
Net Income (Loss) Available to Common Stockholders, Diluted, Total	$ 115,567	$ 86,570
Conversion of Class B to Class A common stock (in shares)	14,837	15,188
Effect of potentially dilutive common shares (in shares)	9,769	9,933
Weighted average shares used in computing net income per share, diluted (in shares)	162,213	159,474
Net income per share, diluted (in usd per share)	$ 0.71	$ 0.54
Class B common stock
Schedule Of Earnings Per Share Basic And Diluted [Line Items]
Net income, basic	$ 11,248	$ 8,793
Weighted average shares used in computing net income per share, basic (in shares)	14,837	15,188
Net income per share, basic (in usd per share)	$ 0.76	$ 0.58
Reallocation as a result of conversion of Class B to Class A common stock:
Net income, basic	$ 0	$ 0
Reallocation of net income to Class B common stock	6,282	4,844
Net Income (Loss) Available to Common Stockholders, Diluted, Total	$ 17,530	$ 13,637
Conversion of Class B to Class A common stock (in shares)	0	0
Effect of potentially dilutive common shares (in shares)	9,769	9,933
Weighted average shares used in computing net income per share, diluted (in shares)	24,606	25,121
Net income per share, diluted (in usd per share)	$ 0.71	$ 0.54