Organization and Description of the Business (Details) - USD ($) $ in Thousands	3 Months Ended
	Sep. 30, 2017	Dec. 31, 2017	Dec. 31, 2016
Liquidity
Accumulated deficit		$ (144,727)	$ (125,829)
Secondary public offering
Liquidity
Issuance of common stock in connection with secondary public offering (in shares)	10,733,334
Proceeds from issuance of common stock, net of issuance costs	$ 37,700