Background (Details) - USD ($)				9 Months Ended
	Sep. 13, 2016	Mar. 03, 2016	Feb. 17, 2016	Sep. 30, 2016
Public Offering
Net proceeds from issuance of common stock				$ 247,228,422
Class B-1 Preferred Stock
Public Offering
Shares converted (in shares)			3,278,938
Class B-2 Preferred Stock
Public Offering
Shares converted (in shares)			326,557
Class C Preferred Stock
Public Offering
Shares converted (in shares)			2,365,020
Class D Preferred Stock
Public Offering
Shares converted (in shares)			3,105,000
Common Stock | IPO
Public Offering
Shares issued (in shares)			4,750,000
Share price (in dollars per share)			$ 20.00
Net proceeds			$ 88,400,000
Common Stock | Over-Allotment Option
Public Offering
Shares issued (in shares)	637,500	527,941
Share price (in dollars per share)		$ 20.00
Net proceeds		$ 9,800,000
Common Stock | Follow-On Offering
Public Offering
Number of common shares to be sold under public offering	4,887,500
Shares issued (in shares)	4,597,645
Share price (in dollars per share)	$ 34.50
Net proceeds from issuance of common stock	$ 149,100,000
Common Stock | Stock Sold by Selling Stockholder
Public Offering
Shares issued (in shares)	289,855