Revenue - Additional Information (Details) - USD ($)	3 Months Ended	9 Months Ended
Sep. 30, 2018	Sep. 30, 2018
Local, National and Digital
Disaggregation Of Revenue [Line Items]
Revenue recognized	$ 500,000	$ 300,000
Special Events
Disaggregation Of Revenue [Line Items]
Revenue recognized	0	100,000
Barter
Disaggregation Of Revenue [Line Items]
Revenue recognized	$ 100,000	$ 300,000

Amount of revenue recognized that was previously included in balance of obligation to transfer good or service to customer for which consideration from customer has been received or is due.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 8
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=109196051&loc=SL49130549-203045

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