| Document and Entity Information | Sep. 17, 2024 |
| Cover [Abstract] | |
| Entity Registrant Name | CASELLA WASTE SYSTEMS INC |
| Amendment Flag | false |
| Entity Central Index Key | 0000911177 |
| Document Type | 8-K |
| Document Period End Date | Sep. 17, 2024 |
| Entity Incorporation State Country Code | DE |
| Entity File Number | 000-23211 |
| Entity Tax Identification Number | 03-0338873 |
| Entity Address, Address Line One | 25 Greens Hill Lane |
| Entity Address, City or Town | Rutland |
| Entity Address, State or Province | VT |
| Entity Address, Postal Zip Code | 05701 |
| City Area Code | (802) |
| Local Phone Number | 775-0325 |
| Written Communications | false |
| Soliciting Material | false |
| Pre Commencement Tender Offer | false |
| Pre Commencement Issuer Tender Offer | false |
| Security 12b Title | Class A common stock, $0.01 par value per share |
| Trading Symbol | CWST |
| Security Exchange Name | NASDAQ |
| Entity Emerging Growth Company | false |
