Convertible Preferred Stock - Summary of Convertible Preferred Stock Outstanding (Detail) - USD ($) $ in Thousands	Jan. 31, 2016	Jan. 31, 2015	Jan. 31, 2014	Jan. 31, 2013
Temporary Equity [Line Items]
Convertible preferred stock, shares authorized	0	123,879,952
Convertible preferred stock, shares issued	0	122,280,679
Convertible preferred stock, shares outstanding	0	122,280,679	104,106,000	79,409,000
Convertible preferred stock, aggregate liquidation preference	$ 0	$ 551,858
Convertible preferred stock, net proceeds	$ 0	$ 543,940	$ 262,970	$ 95,137
Series A Convertible Preferred Stock
Temporary Equity [Line Items]
Convertible preferred stock, shares authorized		24,360,000
Convertible preferred stock, shares issued		24,360,000
Convertible preferred stock, shares outstanding		24,360,000
Convertible preferred stock, aggregate liquidation preference		$ 5,075
Convertible preferred stock, net proceeds		$ 5,038
Series B Convertible Preferred Stock
Temporary Equity [Line Items]
Convertible preferred stock, shares authorized		30,211,506
Convertible preferred stock, shares issued		30,211,506
Convertible preferred stock, shares outstanding		30,211,506
Convertible preferred stock, aggregate liquidation preference		$ 20,000
Convertible preferred stock, net proceeds		$ 19,925
Series C Convertible Preferred Stock
Temporary Equity [Line Items]
Convertible preferred stock, shares authorized		14,253,774
Convertible preferred stock, shares issued		14,253,774
Convertible preferred stock, shares outstanding		14,253,774
Convertible preferred stock, aggregate liquidation preference		$ 30,444
Convertible preferred stock, net proceeds		$ 30,346
Series D Convertible Preferred Stock
Temporary Equity [Line Items]
Convertible preferred stock, shares authorized		10,584,066
Convertible preferred stock, shares issued		10,584,066
Convertible preferred stock, shares outstanding		10,584,066
Convertible preferred stock, aggregate liquidation preference		$ 39,916
Convertible preferred stock, net proceeds		$ 39,828
Series E Convertible Preferred Stock
Temporary Equity [Line Items]
Convertible preferred stock, shares authorized		24,761,984
Convertible preferred stock, shares issued		24,761,984
Convertible preferred stock, shares outstanding		24,761,984
Convertible preferred stock, aggregate liquidation preference		$ 171,637
Convertible preferred stock, net proceeds		$ 168,283
Series F Convertible Preferred Stock
Temporary Equity [Line Items]
Convertible preferred stock, shares authorized		15,897,337
Convertible preferred stock, shares issued		14,307,603
Convertible preferred stock, shares outstanding		14,307,603
Convertible preferred stock, aggregate liquidation preference		$ 225,000
Convertible preferred stock, net proceeds		$ 220,803
Series F-1 Convertible Preferred Stock
Temporary Equity [Line Items]
Convertible preferred stock, shares authorized		3,811,285
Convertible preferred stock, shares issued		3,801,746
Convertible preferred stock, shares outstanding		3,801,746
Convertible preferred stock, aggregate liquidation preference		$ 59,786
Convertible preferred stock, net proceeds		$ 59,717