Basic Net Income (loss) Per Share is Calculated Using Weighted Average Number of Shares (Detail) - $ / shares	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Earnings per share - basic	$ 0.08	$ 0.08	$ 0.15	$ 0.25
Earnings per share - diluted	$ 0.07	$ 0.07	$ 0.13	$ 0.22
Weighted average shares of common stock outstanding - basic	32,674,459	25,067,954	32,548,662	25,067,954
Weighted average shares of common stock outstanding - diluted	37,850,679	28,417,877	37,935,773	28,417,877