Stockholders' Equity - Additional Information (Detail) - USD ($)	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Equity [Abstract]
Preferred stock, shares authorized	10,000,000		10,000,000
Preferred stock, par value	$ 0.001		$ 0.001
Preferred stock, shares issued	0		0
Preferred stock, shares outstanding	0		0
Common stock, shares authorized	200,000,000		200,000,000
Common stock, par value	$ 0.001		$ 0.001
Common stock, shares issued	15,302,455		15,302,455
Common stock, shares outstanding	15,302,455		15,302,455
Employee stock purchase plan expense	$ 2,044	$ 1,738