v3.10.0.1
Document and Entity Information - USD ($)
9 Months Ended
Sep. 30, 2018
Oct. 26, 2018
Document Information [Line Items]    
Document Type 10-Q  
Document Period End Date Sep. 30, 2018  
Amendment Flag false  
Document Fiscal Year Focus 2018  
Document Fiscal Period Focus Q3  
Entity Registrant Name Entercom Communications Corp.  
Entity Central Index Key 0001067837  
Entity Current Reporting Status Yes  
Current Fiscal Year End Date --12-31  
Entity Filer Category Accelerated Filer  
Entity Public Float $ 1,125,970,031  
Trading Symbol ETM  
Common Class A [Member]    
Document Information [Line Items]    
Entity Common Stock Shares Outstanding   138,479,468
Common Class B [Member]    
Document Information [Line Items]    
Entity Common Stock Shares Outstanding   4,045,199