Stockholders’ Equity (Deficit) (Details)	1 Months Ended	12 Months Ended
	Oct. 31, 2017 shares	Jan. 31, 2018 vote $ / shares shares	Jan. 31, 2017 $ / shares shares	Jan. 31, 2016 shares	Jan. 31, 2015 shares
Class A Common Stock
Class of Stock [Line Items]
Number of votes per share | vote		1
Common stock authorized (in shares)		1,000,000,000	162,500,000
Common stock, par value (in dollars per share) | $ / shares		$ 0.001	$ 0.001
Common stock issued (in shares)		13,303,028	0
Common stock outstanding (in shares)		13,303,028	0
Class B Common Stock
Class of Stock [Line Items]
Number of votes per share | vote		10
Period of automatic conversion after death of founder		9 months
Percent of outstanding stock		10.00%
Common stock authorized (in shares)		100,000,000	113,000,000
Common stock, par value (in dollars per share) | $ / shares		$ 0.001	$ 0.001
Common stock issued (in shares)		37,371,914	13,192,992
Common stock outstanding (in shares)		37,272,543	13,093,621
Common Stock
Class of Stock [Line Items]
Conversion of stock, shares converted (in shares)	26,952,887	26,953,404
Common stock outstanding (in shares)		50,575,571	13,093,621	11,565,764	11,001,782
Common Stock | Class B Common Stock
Class of Stock [Line Items]
Conversion of stock, shares converted (in shares)		53,562