Stockholders' Equity (Preferred Stock and Common Stock) - Additional Information (Detail)	Dec. 31, 2018 Vote $ / shares shares	Dec. 31, 2017 $ / shares shares
Equity [Abstract]
Preferred stock, shares authorized	5,000,000	5,000,000
Preferred stock, par value | $ / shares	$ 0.001	$ 0.001
Preferred stock, shares outstanding	0	0
Common stock, shares authorized	150,000,000	150,000,000
Common stock, par value | $ / shares	$ 0.001	$ 0.001
Common stock, shares issued	102,739,257	102,549,498
Common stock, shares outstanding	102,739,257	102,549,498
Number of votes entitled for each share of common stock | Vote	1