Revenue - Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2021	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Revenue.
Revenue from Contract with Customer, Including Assessed Tax	$ 29,151	$ 28,845	$ 28,046	$ 22,301	$ 28,753	$ 24,143	$ 16,866	$ 26,051	$ 108,343	$ 95,813	$ 123,072
Revenue, Remaining Performance Obligation, Optional Exemption, Performance Obligation [true false]									true
Broadcast Advertising Revenue, Net [Member]
Revenue.
Revenue from Contract with Customer, Including Assessed Tax									$ 95,573	87,481	112,278
Digital Advertising Revenue [Member]
Revenue.
Revenue from Contract with Customer, Including Assessed Tax									6,337	3,416	3,783
Other Revenue [Member]
Revenue.
Revenue from Contract with Customer, Including Assessed Tax									$ 6,433	$ 4,916	$ 7,011