Stockholders' Equity (Deficit) - Narrative (Details) $ / shares in Units, $ in Thousands		3 Months Ended		9 Months Ended
	Apr. 06, 2017 shares	Oct. 31, 2017 USD ($) $ / shares shares	Oct. 31, 2016 USD ($) shares	Oct. 31, 2017 USD ($) vote $ / shares shares	Oct. 31, 2016 USD ($) shares	Jan. 31, 2017 $ / shares shares
Class of Stock [Line Items]
Shares authorized, (in shares)						120,000,000
Common stock par value (in dollars per share) | $ / shares						$ 0.0001
General and administrative expenses recognized | $		$ 13,546	$ 7,922	$ 37,133	$ 21,009
Redeemable Convertible Preferred Stock
Class of Stock [Line Items]
Redeemable convertible preferred stock converted to common class B stock (in shares)	59,491,640
Redeemable preferred stock outstanding (in shares)		0		0
Class A Common Stock
Class of Stock [Line Items]
Shares authorized, (in shares)		1,000,000,000		1,000,000,000
Common stock par value (in dollars per share) | $ / shares		$ 0.0001		$ 0.0001
Common stock outstanding (in shares)		39,290,132		39,290,132
Number of votes per share | vote				1
Class B Common Stock
Class of Stock [Line Items]
Common class B stock after conversion of redeemable convertible stock (in shares)	59,491,640
Shares authorized, (in shares)		120,000,000		120,000,000
Common stock par value (in dollars per share) | $ / shares		$ 0.0001		$ 0.0001
Common stock outstanding (in shares)		62,081,326		62,081,326
Number of votes per share | vote				10
Contribution of Nonmonetary Assets to Charitable Organization | Class A Common Stock
Class of Stock [Line Items]
Shares issued as charitable contributions (in shares)		24,287		24,287
General and administrative expenses recognized | $		$ 700		$ 700
Contribution of Nonmonetary Assets to Charitable Organization | Class B Common Stock
Class of Stock [Line Items]
Shares issued as charitable contributions (in shares)			13,935		13,935
General and administrative expenses recognized | $			$ 100		$ 100