Convertible Preferred Stock - Additional Information (Details) - USD ($) $ / shares in Units, $ in Thousands	1 Months Ended			3 Months Ended		6 Months Ended
	Jul. 31, 2017	Jun. 30, 2017	Apr. 30, 2017	Jul. 31, 2017	Jul. 31, 2016	Jul. 31, 2017	Jul. 31, 2016
Temporary Equity [Line Items]
Series E and E-1 Convertible Preferred Stock purchase price			$ 43.47828
Series E and E-1 Convertible Preferred Stock threshold of stock price trigger			$ 47.826108
Deemed dividend to Series E and E-1 Convertible Preferred Stock			$ 6,600	$ 0	$ 0	$ (6,588)	$ 0
Conversion of convertible preferred stock		7,382,007
Number of common stock purchase		1,666,665
Warrant exercisable period		10 years
Warrant exercised price		$ 16.44
Impact of adjustment to Series E, E-1 and F Convertible Preferred Stock				26,336	$ 0	26,336	0
Common stock warrants issued to Series E-2 and F-2 Holders						14,641	$ 0
Additional loan drawn	$ 50,000			50,000		50,000
New Facility Agreement
Temporary Equity [Line Items]
Additional loan drawn	$ 10,000			$ 10,000		$ 10,000
Common Stock | IPO
Temporary Equity [Line Items]
Conversion of convertible preferred stock	17,992,973					17,992,973
Convertible Preferred Stock Warrants
Temporary Equity [Line Items]
Conversion of convertible preferred stock						68,633
Common Stock Warrants
Temporary Equity [Line Items]
Conversion of stock	205,897			205,897		205,897
Warrants exercisable upon additional loan drawn	34,058			34,058		34,058