Basic Net Income (loss) Per Share is Calculated Using Weighted Average Number of Shares (Detail) - $ / shares	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Earnings per share – basic	$ 0.33	$ 1.01
Earnings per share – diluted	$ 0.29	$ 0.90
Weighted average shares of common stock outstanding – basic	32,893,940	25,525,786
Weighted average shares of common stock outstanding - diluted	37,914,886	28,661,735