Net Loss per Share Attributable to Common Stockholders - Summary of Computation of Basic and Diluted Net Loss per Share Attributable to Common Stockholders (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	12 Months Ended
	Jan. 31, 2019	Jan. 31, 2018	[3]	Jan. 31, 2017	[3]
Earnings Per Share [Abstract]
Net loss	$ (178,362)	$ (159,878)	[1],[2]	$ (221,532)	[1],[2]
Weighted-average shares used in computing net loss per share attributable to common stockholders, basic and diluted (in shares)	232,042	211,609		194,714
Net loss per share attributable to common stockholders, basic and diluted (in dollars per share)	$ (0.77)	$ (0.76)		$ (1.14)

[1] * As adjusted to reflect the impact of ASU 2016-18 and the full retrospective adoption of

[2] * As adjusted to reflect the impact of the full retrospective adoption of ASC 606 - see Note 2.

[3] *As adjusted to reflect the impact of the full retrospective adoption of ASC 606 - see Note 2.