Net Income (Loss) Per Share Attributable to Common Stockholders - Summary of Potential Shares of Common Stock Excluded from Computation of Diluted Net Loss Per Share Attributable to Common Stockholders (Details) - shares	3 Months Ended
	Apr. 30, 2019	Apr. 30, 2018
Class A Common Stock
Earnings Per Share Basic [Line Items]
Antidilutive securities excluded from computation of earnings per share	161,650
Class B Common Stock
Earnings Per Share Basic [Line Items]
Antidilutive securities excluded from computation of earnings per share	19,663	190,442,885
Class B Common Stock | Convertible Preferred Stock
Earnings Per Share Basic [Line Items]
Antidilutive securities excluded from computation of earnings per share		152,665,804
Outstanding Stock Option | Class A Common Stock
Earnings Per Share Basic [Line Items]
Antidilutive securities excluded from computation of earnings per share	161,650
Outstanding Stock Option | Class B Common Stock
Earnings Per Share Basic [Line Items]
Antidilutive securities excluded from computation of earnings per share	19,663	35,724,598
Shares Subject to Repurchase From Early Exercised Stock Options and Restricted Stock | Class B Common Stock
Earnings Per Share Basic [Line Items]
Antidilutive securities excluded from computation of earnings per share		2,052,483