Acquisitions - Schedule of Unaudited Pro Forma Information (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Cisneros Interactive
Pro Forma:
Total revenue	$ 199,008	$ 116,248	$ 526,298	$ 307,868
Net income (loss)	13,884	(12,168)	31,362	(18,332)
Net income (loss) attributable to common stockholders	$ 13,884	$ (12,168)	$ 31,362	$ (18,332)
Basic and diluted earnings per share:
Net income (loss) per share, attributable to common stockholders, basic	$ 0.16	$ 0.14	$ 0.37	$ (0.22)
Net income (loss) per share, attributable to common stockholders, diluted	$ 0.16	$ 0.14	$ 0.36	$ (0.22)
Weighted average common shares outstanding, basic	85,390,333	84,185,728	85,207,992	84,208,924
Weighted average common shares outstanding, diluted	88,315,732	84,863,020	87,694,395	84,208,924
MediaDonuts
Pro Forma:
Total revenue	$ 199,008	$ 70,859	$ 547,941	$ 187,518
Net income (loss)	$ 12,131	$ (9,688)
Net income (loss) attributable to common stockholders			$ 28,605	$ (22,539)
Basic and diluted earnings per share:
Net income (loss) per share, attributable to common stockholders, basic	$ 0.14	$ 0.12	$ 0.34	$ (0.27)
Net income (loss) per share, attributable to common stockholders, diluted	$ 0.14	$ 0.11	$ 0.33	$ (0.27)
Weighted average common shares outstanding, basic	85,390,333	84,185,728	85,207,992	84,208,924
Weighted average common shares outstanding, diluted	88,315,732	84,863,020	87,694,395	84,208,924