Revenues - Summary of Disaggregation of Broadcast Advertising Revenue by Sales Channel (Detail) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Disaggregation Of Revenue [Line Items]
Total revenue	$ 45,116	$ 69,241	$ 109,365	$ 133,921
Advertising
Disaggregation Of Revenue [Line Items]
Total revenue	22,589	37,237	61,317	71,945
Advertising \| Local Direct
Disaggregation Of Revenue [Line Items]
Total revenue	4,093	6,456	9,936	12,511
Advertising \| Local Agency
Disaggregation Of Revenue [Line Items]
Total revenue	7,873	14,966	21,439	28,666
Advertising \| National Agency
Disaggregation Of Revenue [Line Items]
Total revenue	$ 10,623	$ 15,815	$ 29,942	$ 30,768

Amount, excluding tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value added and excise.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 4
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=118956577&loc=SL49130543-203045

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=118956577&loc=SL49130545-203045

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration