Net Loss Per Share - Schedule of Basic and Diluted Net Loss Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended			9 Months Ended
	Oct. 31, 2018	Oct. 31, 2017		Oct. 31, 2018	Oct. 31, 2017
Numerator:
Net loss	$ (29,517)	$ (33,066)	[1],[2]	$ (94,686)	$ (86,804)	[1],[3]
Denominator:
Weighted-average shares outstanding - basic and diluted (in shares)	108,776	95,474	[1]	106,587	76,950	[1]
Net loss per share attributable to common stockholders, basic and diluted (in dollars per share)	$ (0.27)	$ (0.35)	[1]	$ (0.89)	$ (1.13)	[1]
Class A Common Stock
Numerator:
Net loss	$ (26,502)	$ (8,672)		$ (79,991)	$ (16,366)
Denominator:
Weighted-average shares outstanding - basic and diluted (in shares)	97,665	25,039		90,045	14,508
Net loss per share attributable to common stockholders, basic and diluted (in dollars per share)	$ (0.27)	$ (0.35)		$ (0.89)	$ (1.13)
Class B Common Stock
Numerator:
Net loss	$ (3,015)	$ (24,394)		$ (14,695)	$ (70,438)
Denominator:
Weighted-average shares outstanding - basic and diluted (in shares)	11,111	70,435		16,542	62,442
Net loss per share attributable to common stockholders, basic and diluted (in dollars per share)	$ (0.27)	$ (0.35)		$ (0.89)	$ (1.13)

[1] See Note 2 for a summary of adjustments.

[2] See Note 2 for a summary of adjustments.

[3] See Note 2 for a summary of adjustments.