| Cover Page - shares | 3 Months Ended | |
| Mar. 31, 2020 | Apr. 30, 2020 | |
| Document Information [Line Items] | ||
| Document Type | 10-Q/A | |
| Document Quarterly Report | true | |
| Document Period End Date | Mar. 31, 2020 | |
| Document Transition Report | false | |
| Entity File Number | 01-14461 | |
| Entity Registrant Name | Entercom Communications Corp. | |
| Entity Incorporation, State or Country Code | PA | |
| Entity Tax Identification Number | 23-1701044 | |
| Entity Address, Address Line One | 2400 Market Street | |
| Entity Address, Address Line Two | 4th Floor | |
| Entity Address, City or Town | Philadelphia | |
| Entity Address, State or Province | PA | |
| Entity Address, Postal Zip Code | 19103 | |
| City Area Code | (610) | |
| Local Phone Number | 660-5610 | |
| Entity Current Reporting Status | Yes | |
| Entity Interactive Data Current | Yes | |
| Entity Filer Category | Large Accelerated Filer | |
| Entity Emerging Growth Company | false | |
| Entity Small Business | false | |
| Entity Shell Company | false | |
| Title of 12(b) Security | Class A Common Stock, par value $.01 per share | |
| Trading Symbol | ETM | |
| Security Exchange Name | NYSE | |
| Amendment Flag | false | |
| Document Fiscal Year Focus | 2020 | |
| Document Fiscal Period Focus | Q1 | |
| Entity Central Index Key | 0001067837 | |
| Current Fiscal Year End Date | --12-31 | |
| Common Class A | ||
| Document Information [Line Items] | ||
| Entity Common Stock, Shares Outstanding | 133,982,984 | |
| Common Class B | ||
| Document Information [Line Items] | ||
| Entity Common Stock, Shares Outstanding | 4,045,199 |
