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		9 Months Ended
	Oct. 31, 2014	Oct. 31, 2013	Oct. 31, 2014	Oct. 31, 2013
Schedule Of Earnings Per Share Basic And Diluted [Line Items]
Net income	$ 10,258	$ 6,525	$ 27,057	$ 17,368
Net income attributable to common stockholders, basic	10,198	2,339	26,851	4,613
Weighted average shares used in computing net income per share attributable to common stockholders, basic	129,212	35,802	126,836	28,519
Net income per share attributable to common stockholders, basic	$ 0.08	$ 0.07	$ 0.21	$ 0.16
Basic	10,198	2,339	26,851	4,613
Reallocation as a result of conversion of Class B to Class A common stock:
Net income attributable to common stockholders, diluted	10,198	6,387	26,851	16,937
Number of shares used for basic EPS computation	129,212	35,802	126,836	28,519
Weighted average shares used in computing net income per share attributable to common stockholders, diluted	144,289	131,963	144,082	129,601
Net income per share attributable to common stockholders, diluted	$ 0.07	$ 0.05	$ 0.19	$ 0.13
Class A common stock [Member]
Schedule Of Earnings Per Share Basic And Diluted [Line Items]
Net income	4,358	328	8,630	365
Noncumulative dividends on convertible preferred stock		(6)		(8)
Undistributed earnings allocated to participating securities	(25)	(204)	(66)	(260)
Net income attributable to common stockholders, basic	4,333	118	8,564	97
Weighted average shares used in computing net income per share attributable to common stockholders, basic	54,897	1,800	40,454	600
Net income per share attributable to common stockholders, basic	$ 0.08	$ 0.07	$ 0.21	$ 0.16
Basic	4,333	118	8,564	97
Noncumulative dividends on convertible preferred stock		6		8
Undistributed earnings allocated to participating securities		204		260
Reallocation as a result of conversion of Class B to Class A common stock:
Net income attributable to common stockholders, basic	5,865	2,221	18,287	4,516
Noncumulative dividends on convertible preferred stock		119		396
Undistributed earnings allocated to participating securities		3,857		12,091
Reallocation of net income to Class B common stock		(138)		(431)
Net income attributable to common stockholders, diluted	10,198	6,387	26,851	16,937
Number of shares used for basic EPS computation	54,897	1,800	40,454	600
Conversion of Class B to Class A common stock	74,315	34,002	86,382	27,919
Effect of potentially dilutive common shares	15,077	19,639	17,246	18,939
Effect of conversion of preferred stock upon IPO		76,522		82,143
Weighted average shares used in computing net income per share attributable to common stockholders, diluted	144,289	131,963	144,082	129,601
Net income per share attributable to common stockholders, diluted	$ 0.07	$ 0.05	$ 0.19	$ 0.13
Class B common stock [Member]
Schedule Of Earnings Per Share Basic And Diluted [Line Items]
Net income	5,900	6,197	18,427	17,003
Noncumulative dividends on convertible preferred stock		(119)		(396)
Undistributed earnings allocated to participating securities	(35)	(3,857)	(140)	(12,091)
Net income attributable to common stockholders, basic	5,865	2,221	18,287	4,516
Weighted average shares used in computing net income per share attributable to common stockholders, basic	74,315	34,002	86,382	27,919
Net income per share attributable to common stockholders, basic	$ 0.08	$ 0.07	$ 0.21	$ 0.16
Basic	5,865	2,221	18,287	4,516
Noncumulative dividends on convertible preferred stock		119		396
Undistributed earnings allocated to participating securities		3,857		12,091
Reallocation as a result of conversion of Class B to Class A common stock:
Reallocation of net income to Class B common stock	453	(138)	1,025	(431)
Net income attributable to common stockholders, diluted	$ 6,318	$ 6,059	$ 19,312	$ 16,572
Number of shares used for basic EPS computation	74,315	34,002	86,382	27,919
Effect of potentially dilutive common shares	15,077	19,639	17,246	18,939
Effect of conversion of preferred stock upon IPO		76,522		82,143
Weighted average shares used in computing net income per share attributable to common stockholders, diluted	89,392	130,163	103,628	129,001
Net income per share attributable to common stockholders, diluted	$ 0.07	$ 0.05	$ 0.19	$ 0.13