Business Overview - Additional Information (Details) $ / shares in Units, $ in Thousands	1 Months Ended	12 Months Ended
	Oct. 31, 2015 USD ($) $ / shares shares	Jan. 31, 2018 USD ($) class	Jan. 31, 2017 USD ($)	Jan. 31, 2016 USD ($)
Class of Stock [Line Items]
Net proceeds from initial public offering		$ 0	$ 0	$ 459,425
Number of classes of stock | class		2
IPO
Class of Stock [Line Items]
Net proceeds from initial public offering	$ 459,400
Underwriting discounts and commissions	29,300
Offering costs incurred	$ 4,500
IPO | Class A common stock
Class of Stock [Line Items]
Issuance of common stock upon initial public offering (in shares) | shares	28,750,000
Issue price per share (in dollars per share) | $ / shares	$ 17.00
IPO | Class B common stock
Class of Stock [Line Items]
Conversion of preferred stock (in shares) | shares	122,280,679