Net Income per Share Attributable to Common Stockholders - Numerators and Denominators of the Basic and Diluted EPS Computations for Common Stock (Detail) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended
	Apr. 30, 2014	Apr. 30, 2013
Schedule Of Earnings Per Share Basic And Diluted [Line Items]
Net income	$ 7,221	$ 4,845
Weighted average shares used in computing net income per share attributable to common stockholders, basic	123,902	21,610
Net income per share attributable to common stockholders, basic	$ 0.06	$ 0.04
Reallocation as a result of conversion of Class B to Class A common stock:
Number of shares used for basic EPS computation	123,902	21,610
Weighted average shares used in computing net income per share attributable to common stockholders, diluted	142,849	32,988
Net income per share attributable to common stockholders, diluted	$ 0.05	$ 0.03
Class A common stock [Member]
Schedule Of Earnings Per Share Basic And Diluted [Line Items]
Net income	1,258
Noncumulative dividends on convertible preferred stock
Undistributed earnings allocated to participating securities	(16)
Net income attributable to common stockholders, basic	1,242
Weighted average shares used in computing net income per share attributable to common stockholders, basic	21,589
Net income per share attributable to common stockholders, basic	$ 0.06
Net income attributable to common stockholders, basic	1,242
Reallocation as a result of conversion of Class B to Class A common stock:
Net income attributable to common stockholders, basic	5,886
Reallocation of net income to Class B common stock
Net income attributable to common stockholders, diluted	7,128
Number of shares used for basic EPS computation	21,589
Conversion of Class B to Class A common stock	102,313
Effect of potentially dilutive securities	18,947
Weighted average shares used in computing net income per share attributable to common stockholders, diluted	142,849
Net income per share attributable to common stockholders, diluted	$ 0.05
Class B common stock [Member]
Schedule Of Earnings Per Share Basic And Diluted [Line Items]
Net income	5,963	4,845
Noncumulative dividends on convertible preferred stock		(140)
Undistributed earnings allocated to participating securities	(77)	(3,779)
Net income attributable to common stockholders, basic	5,886	926
Weighted average shares used in computing net income per share attributable to common stockholders, basic	102,313	21,610
Net income per share attributable to common stockholders, basic	$ 0.06	$ 0.04
Net income attributable to common stockholders, basic	5,886	926
Reallocation as a result of conversion of Class B to Class A common stock:
Net income attributable to common stockholders, basic
Reallocation of net income to Class B common stock	165
Net income attributable to common stockholders, diluted	$ 6,051	$ 926
Number of shares used for basic EPS computation	102,313	21,610
Conversion of Class B to Class A common stock
Effect of potentially dilutive securities	18,947	11,378
Weighted average shares used in computing net income per share attributable to common stockholders, diluted	121,260	32,988
Net income per share attributable to common stockholders, diluted	$ 0.05	$ 0.03