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		9 Months Ended
	Oct. 31, 2021	Oct. 31, 2020	Oct. 31, 2021	Oct. 31, 2020
Schedule Of Earnings Per Share Basic And Diluted [Line Items]
Weighted average shares used in computing net income per share, basic (in shares)	153,514	150,993	153,020	150,322
Net income per share, basic (in usd per share)	$ 0.69	$ 0.64	$ 2.16	$ 1.84
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)	163,034	161,711	162,663	160,517
Net income per share, diluted (in usd per share)	$ 0.65	$ 0.60	$ 2.03	$ 1.73
Class A common stock
Schedule Of Earnings Per Share Basic And Diluted [Line Items]
Net income, basic	$ 95,691	$ 87,262	$ 298,379	$ 249,155
Weighted average shares used in computing net income per share, basic (in shares)	138,755	135,892	138,234	135,172
Net income per share, basic (in usd per share)	$ 0.69	$ 0.64	$ 2.16	$ 1.84
Reallocation as a result of conversion of Class B to Class A common stock:
Net income, basic	$ 10,178	$ 9,697	$ 31,915	$ 27,925
Reallocation of net income to Class B common stock	0	0	0	0
Net income, diluted	$ 105,869	$ 96,959	$ 330,294	$ 277,080
Conversion of Class B to Class A common stock (in shares)	14,759	15,101	14,786	15,150
Effect of potentially dilutive common shares (in shares)	9,520	10,718	9,643	10,195
Weighted average shares used in computing net income per share, diluted (in shares)	163,034	161,711	162,663	160,517
Net income per share, diluted (in usd per share)	$ 0.65	$ 0.60	$ 2.03	$ 1.73
Class B common stock
Schedule Of Earnings Per Share Basic And Diluted [Line Items]
Net income, basic	$ 10,178	$ 9,697	$ 31,915	$ 27,925
Weighted average shares used in computing net income per share, basic (in shares)	14,759	15,101	14,786	15,150
Net income per share, basic (in usd per share)	$ 0.69	$ 0.64	$ 2.16	$ 1.84
Reallocation as a result of conversion of Class B to Class A common stock:
Net income, basic	$ 0	$ 0	$ 0	$ 0
Reallocation of net income to Class B common stock	5,588	5,784	17,690	15,825
Net income, diluted	$ 15,766	$ 15,481	$ 49,605	$ 43,750
Conversion of Class B to Class A common stock (in shares)	0	0	0	0
Effect of potentially dilutive common shares (in shares)	9,520	10,718	9,643	10,195
Weighted average shares used in computing net income per share, diluted (in shares)	24,279	25,819	24,429	25,345
Net income per share, diluted (in usd per share)	$ 0.65	$ 0.60	$ 2.03	$ 1.73