Stockholders' Equity - Additional Information (Details) - $ / shares		12 Months Ended
	Jun. 15, 2018	Jan. 31, 2019	Jun. 14, 2018	Jan. 31, 2018	Jan. 31, 2015
Class Of Stock [Line Items]
Capital stock shares authorized					1,300,000,000
Common Stock, par value					$ 0.0001
Preferred stock, shares authorized		100,000,000		100,000,000	100,000,000
Preferred stock, par value		$ 0.0001		$ 0.0001	$ 0.0001
Common Stock, conversion features		On June 14, 2018, all of our outstanding shares of Class B common stock automatically converted into the same number of shares of Class A common stock pursuant to the terms of our Amended and Restated Certification of Incorporation. No additional shares of Class B common stock will be issued following such conversion. The conversion occurred pursuant to Article IV of the Amended and Restated Certificate of Incorporation, which provided that each one share of Class B common stock would convert automatically, without any further action, into one share of Class A common stock on the first trading day falling on or after the date on which the outstanding shares of Class B common stock represent less than 5% of the aggregate number of shares of the then outstanding Class A common stock and Class B common stock.
Preferred stock, shares issued		0		0
Preferred stock, shares outstanding		0		0
Treasury Stock, shares		3,052,953		3,052,953
Class A Common Stock
Class Of Stock [Line Items]
Common Stock, par value		$ 0.0001		$ 0.0001
Common Stock, shares authorized		1,000,000,000		1,000,000,000	1,000,000,000
Common stock, voting rights		1 vote per share
Common Stock, shares issued		144,310,746		125,933,323
Common Stock, shares outstanding		144,310,746		125,933,323
Class B Common Stock
Class Of Stock [Line Items]
Common Stock, par value				$ 0.0001
Common Stock, shares authorized				200,000,000	200,000,000
Common stock, voting rights		10 votes per share
Common Stock, conversion features		Established that shares of our Class B common stock are voluntarily convertible into shares of our Class A common stock at the option of the holder, generally automatically convertible into shares of our Class A common stock upon transfer, and all outstanding shares of our Class B common stock will automatically convert into shares of our Class A common stock once the aggregate number of shares of our Class B common stock represents less than 5% of the then outstanding shares of Class A and Class B common stock.
Maximum percentage of outstanding shares of Class A and Class B common stock, for automatic conversion of shares of Class B common stock		5.00%	5.00%
Additional common shares issued			0
Reduction in number of authorized shares of common stock	200,000,000
Common Stock, shares issued			0	11,383,525
Common Stock, shares outstanding				11,383,525