Acquisitions - Schedule of Unaudited Pro Forma Information (Detail) - Smadex - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Pro Forma:
Total revenue	$ 76,213	$ 71,787	$ 145,085	$ 130,314
Net income (loss)	$ 5,234	$ 3,538	$ 3,320	$ 6,112
Basic and diluted earnings per share:
Net income per share, basic and diluted	$ 0.06	$ 0.04	$ 0.04	$ 0.07
Weighted average common shares outstanding, basic	88,959,935	90,354,982	89,635,759	90,296,057
Weighted average common shares outstanding, diluted	90,021,949	92,033,111	90,805,086	91,897,150