Stockholders' Equity - Schedule of Restricted Stock Activity (Detail) $ / shares in Units, $ in Thousands	6 Months Ended
	Jul. 31, 2017 USD ($) $ / shares shares
Restricted Stock Outstanding
Ending Balance (in shares)	24,309,030
Restricted Stock Outstanding Weighted-Average Exercise Price
Weighted- Average Exercise Price, Restricted Stock Outstanding, Balance (in dollars per share) | $ / shares	$ 0.001
Restricted stock units and awards
Restricted Stock Outstanding
Beginning Balance (in shares)	27,453,498
Granted, Outstanding (in shares)	1,886,779
Canceled, Outstanding (in shares)	(1,100,273)
Vested and converted to shares, Outstanding (in shares)	(3,930,974)
Ending Balance (in shares)	24,309,030
Expected to vest, Outstanding (in shares)	21,017,129
Restricted Stock Outstanding Weighted-Average Exercise Price
Weighted- Average Exercise Price, Restricted Stock Outstanding, Balance (in dollars per share) | $ / shares	$ 0.001
Weighted- Average Exercise Price, Restricted Stock Outstanding, Granted (in dollars per share) | $ / shares	0.001
Weighted- Average Exercise Price, Restricted Stock Outstanding, Canceled (in dollars per share) | $ / shares	0.001
Weighted- Average Exercise Price, Restricted Stock Outstanding, Vested and converted to shares (in dollars per share) | $ / shares	0.001
Weighted- Average Exercise Price, Restricted Stock Outstanding, Balance (in dollars per share) | $ / shares	$ 0.001
Restricted Stock Outstanding Aggregate Intrinsic Value
Aggregate Intrinsic Value, Ending Balance | $	$ 2,207,260
Aggregate Intrinsic Value, Expected to vest | $	$ 1,908,355