Nature of Business and Significant Accounting Policies - Barter, Advertising and Marketing Costs (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Barter transactions:
Barter revenue	$ 872	$ 877
Barter expense	(557)	(583)
Barter revenue and expense	315	294
Advertising and Marketing costs:
Advertising and marketing costs	$ 3,700	$ 3,000