v3.8.0.1
Document and Entity Information - USD ($)
12 Months Ended
Dec. 31, 2017
Mar. 06, 2018
Document Information [Line Items]    
Document Type 10-K  
Document Period End Date Dec. 31, 2017  
Amendment Flag false  
Document Fiscal Year Focus 2017  
Document Fiscal Period Focus FY  
Entity Registrant Name Entercom Communications Corp.  
Entity Central Index Key 0001067837  
Entity Current Reporting Status Yes  
Entity Voluntary Filers No  
Current Fiscal Year End Date --12-31  
Entity Filer Category Accelerated Filer  
Entity Well Known Seasoned Issuer No  
Entity Public Float $ 1,552,186,584  
Trading Symbol ETM  
Common Class A [Member]    
Document Information [Line Items]    
Entity Common Stock Shares Outstanding   137,501,236
Common Class B [Member]    
Document Information [Line Items]    
Entity Common Stock Shares Outstanding   4,045,199