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 Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Jan. 31, 2014	Oct. 31, 2013	Jul. 31, 2013	Apr. 30, 2013	Jan. 31, 2013	Oct. 31, 2012	Jul. 31, 2012	Apr. 30, 2012	Jan. 31, 2014	Jan. 31, 2013	Jan. 31, 2012
Schedule Of Earnings Per Share Basic And Diluted [Line Items]
Net income	$ 6,247	$ 6,525	$ 5,998	$ 4,845	$ 5,684	$ 5,749	$ 4,247	$ 3,103	$ 23,615	$ 18,783	$ 4,230
Weighted average shares used in computing net income per share attributable to common stockholders, basic									51,725,000	20,887,000	17,655,000
Net income per share attributable to common stockholders, basic									$ 0.20	$ 0.17	$ 0.03
Number of shares used for basic EPS computation									51,725,000	20,887,000	17,655,000
Weighted average shares used in computing net income per share attributable to common stockholders, diluted									68,024,000	30,599,000	24,776,000
Net income per share attributable to common stockholders, diluted									$ 0.15	$ 0.11	$ 0.02
Class A common stock [Member]
Schedule Of Earnings Per Share Basic And Diluted [Line Items]
Net income									1,934
Noncumulative dividends on convertible preferred stock									(33)
Undistributed earnings allocated to participating securities									(1,049)
Net income attributable to common stockholders, basic									852
Weighted average shares used in computing net income per share attributable to common stockholders, basic									4,237,000
Net income per share attributable to common stockholders, basic									$ 0.20
Net income attributable to common stockholders, basic									852
Net income attributable to common stockholders, basic									9,553
Reallocation of net income to Class B common stock
Net income attributable to common stockholders, diluted									10,405
Number of shares used for basic EPS computation									4,237,000
Conversion of Class B to Class A common stock									47,488,000
Effect of potentially dilutive securities									16,299,000
Weighted average shares used in computing net income per share attributable to common stockholders, diluted									68,024,000
Net income per share attributable to common stockholders, diluted									$ 0.15
Class B common stock [Member]
Schedule Of Earnings Per Share Basic And Diluted [Line Items]
Net income									21,681	18,783	4,230
Noncumulative dividends on convertible preferred stock									(371)	(560)	(560)
Undistributed earnings allocated to participating securities									(11,757)	(14,743)	(3,071)
Net income attributable to common stockholders, basic									9,553	3,480	599
Weighted average shares used in computing net income per share attributable to common stockholders, basic									47,488,000	20,887,000	17,655,000
Net income per share attributable to common stockholders, basic									$ 0.20	$ 0.17	$ 0.03
Net income attributable to common stockholders, basic									9,553	3,480	599
Net income attributable to common stockholders, basic
Reallocation of net income to Class B common stock									204
Net income attributable to common stockholders, diluted									$ 9,757	$ 3,480	$ 599
Number of shares used for basic EPS computation									47,488,000	20,887,000	17,655,000
Conversion of Class B to Class A common stock
Effect of potentially dilutive securities									16,299,000	9,712,000	7,121,000
Weighted average shares used in computing net income per share attributable to common stockholders, diluted									63,787,000	30,599,000	24,776,000
Net income per share attributable to common stockholders, diluted									$ 0.15	$ 0.11	$ 0.02