Acquisitions - Schedule of Unaudited Pro Forma Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Headway
Pro Forma:
Total revenue	$ 545,592	$ 288,710
Net income (loss)	$ 176,733	$ 20,282
Basic and diluted earnings per share:
Net income per share, basic	$ 1.95	$ 0.23
Net income per share, diluted	$ 1.92	$ 0.22
Weighted average common shares outstanding, basic	90,272,257	89,340,589
Weighted average common shares outstanding, diluted	91,891,957	91,303,056
KMIR-TV and KPSE-LD
Pro Forma:
Total revenue	$ 543,355	$ 267,614
Net income (loss)	$ 176,894	$ 21,574
Basic and diluted earnings per share:
Net income per share, basic	$ 1.96	$ 0.24
Net income per share, diluted	$ 1.92	$ 0.24
Weighted average common shares outstanding, basic	90,272,257	89,340,589
Weighted average common shares outstanding, diluted	91,891,957	91,303,056