Organization and Description of the Business (Details) $ in Thousands	3 Months Ended
	Sep. 30, 2017 USD ($) shares	Sep. 30, 2018 USD ($) item	Dec. 31, 2017 USD ($)
Number of dose forms for modulator | item		3
Liquidity
Accumulated deficit		$ (171,341)	$ (144,727)
Secondary public offering
Liquidity
Issuance of common stock in connection with secondary public offering (in shares) | shares	10,733,334
Proceeds from issuance of common stock, net of issuance costs	$ 37,700