Stockholders' Equity - Additional Information (Details)	Oct. 31, 2017 class $ / shares shares	Jan. 31, 2017 $ / shares shares
Class Of Stock [Line Items]
Preferred stock, shares authorized (in shares)	20,000,000	20,000,000
Preferred stock, shares issued (in shares)	0	0
Preferred stock, shares outstanding (in shares)	0	0
Number of classes of stock | class	2
Common stock, shares authorized (in shares)	2,250,000,000	2,250,000,000
Common stock, par value per share (in dollars per share) | $ / shares	$ 0.0001	$ 0.0001
Common stock, shares issued (in shares)	216,016,000	204,364,000
Common stock, shares outstanding (in shares)	216,016,000	204,364,000
Class A
Class Of Stock [Line Items]
Common stock, shares authorized (in shares)	2,000,000,000	2,000,000,000
Common stock, par value per share (in dollars per share) | $ / shares	$ 0.0001	$ 0.0001
Common stock, shares issued (in shares)	109,177,866	87,027,000
Common stock, shares outstanding (in shares)	109,177,866	87,027,000
Class B
Class Of Stock [Line Items]
Common stock, shares authorized (in shares)	250,000,000	250,000,000
Common stock, par value per share (in dollars per share) | $ / shares	$ 0.0001	$ 0.0001
Common stock, shares issued (in shares)	106,837,859	117,337,000
Common stock, shares outstanding (in shares)	106,837,859	117,337,000