Revenues - Summary of Disaggregation of Broadcast Advertising Revenue by Sales Channel (Detail) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Disaggregation Of Revenue [Line Items]
Total revenue	$ 68,816	$ 74,575	$ 202,737	$ 215,742
Advertising
Disaggregation Of Revenue [Line Items]
Total revenue	37,345	40,183	109,290	119,425
Advertising \| Local Direct
Disaggregation Of Revenue [Line Items]
Total revenue	6,781	6,750	19,292	20,725
Advertising \| Local Agency
Disaggregation Of Revenue [Line Items]
Total revenue	14,655	15,267	43,321	45,381
Advertising \| National Agency
Disaggregation Of Revenue [Line Items]
Total revenue	$ 15,909	$ 18,166	$ 46,677	$ 53,319

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