Stockholders' Equity - Additional Information (Details) - $ / shares	Sep. 30, 2018	Dec. 31, 2017
Equity [Abstract]
Preferred stock, shares authorized	5,000,000	5,000,000
Preferred stock, par value	$ 0.0001	$ 0.0001
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock shares authorized	75,000,000	75,000,000
Common stock par value	$ 0.0001	$ 0.0001
Common stock shares issued	17,074,636	16,752,171
Common stock shares outstanding	17,074,636	16,752,171
Common stock issued subject to repurchase related to early exercise of options	182,507	289,334