Equity - Warrants - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2017	Dec. 31, 2016
Equity [Abstract]
Shares issued, exercise of warrants	1,844,585
Proceeds from exercise of warrants, gross of transaction costs	$ 2,800
Proceeds from exercise of warrants, net of transaction costs	$ 2,713
Warrants outstanding		0	0