Stockholders' Equity - Additional Information (Detail) (USD $)	3 Months Ended		6 Months Ended
	Jul. 31, 2014	Jul. 31, 2013	Jul. 31, 2014	Jul. 31, 2013	Jan. 31, 2014
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Unvested shares subject to repurchase at an aggregate price	$ 200,000		$ 200,000		$ 500,000
Weighted-average grant date fair value of options granted	$ 9.79	$ 3.39	$ 13.80	$ 2.47
Unrecognized compensation cost, net of estimated forfeitures, related to unvested stock options granted	38,800,000		38,800,000
Weighted average period of unvested stock options			4 years 9 months 18 days
Closing stock price	$ 23.80		$ 23.80
Intrinsic value of options exercised	31,700,000		62,458,072
2013 Employee Stock Purchase Plan [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock acquire at fair market value			85.00%
Common stock purchases through payroll deductions			15.00%
Common stock shares purchased under ESPP	350,059		350,059
Restricted Stock Units (RSUs) [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Weighted average grant date fair value, RSUs Granted	$ 22.03		$ 24.35
Unrecognized compensation cost, net of estimated forfeitures, related to unvested RSUs	$ 13,300,000		$ 13,300,000
Weighted-average period related to unvested restricted stock unit			3 years 7 months 6 days
Class A common stock [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock, shares outstanding	51,320,771		51,320,771		15,044,750
Class B common stock [Member]
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock, shares outstanding	78,088,842		78,088,842		109,746,795
Common stock, shares unvested	968,957		968,957		1,824,457