Subsequent Events (Details) - USD ($) $ / shares in Units, $ in Thousands			3 Months Ended
	Dec. 20, 2017	Nov. 16, 2017	Oct. 28, 2017	Nov. 17, 2017
Subsequent Event [Line Items]
Offering costs			$ 528
Subsequent Event
Subsequent Event [Line Items]
Shares of preferred stock outstanding				0
Subsequent Event | Preferred Stock Warrants
Subsequent Event [Line Items]
Preferred stock warrants outstanding				0
IPO | Subsequent Event
Subsequent Event [Line Items]
Net proceeds from IPO		$ 110,400
Underwriting discounts		6,200
Offering costs		$ 3,400
IPO | Class A Common Stock | Subsequent Event
Subsequent Event [Line Items]
Stock issued during period		8,000,000
Shares Issued, price per share		$ 15.00
IPO | Class B Common Stock | Subsequent Event
Subsequent Event [Line Items]
Convertible preferred stock converted		59,511,055
Outstanding preferred stock warrants exercised		1,066,225
Underwriters' Over-Allotment Option | Class A Common Stock | Subsequent Event
Subsequent Event [Line Items]
Stock issued during period	1,175,557
Shares Issued, price per share	$ 15.00
Net proceeds after deducting underwriting discounts and expenses	$ 16,700