BASIS OF PRESENTATION	12 Months Ended
BASIS OF PRESENTATION	Dec. 31, 2020
Organization, Consolidation and Presentation of Financial Statements [Abstract]
BASIS OF PRESENTATION	BASIS OF PRESENTATION Casella Waste Systems, Inc. (“Parent”), its consolidated subsidiaries and any partially owned entities over which it has a controlling financial interest (collectively, “we”, “us” or “our”), is a regional, vertically integrated solid waste services company that provides collection, transfer, disposal, landfill, landfill gas-to-energy, recycling and organics services in the northeastern United States. We market recyclable metals, aluminum, plastics, paper, and corrugated cardboard, which have been processed at our recycling facilities, as well as recyclables purchased from third-parties. Effective January 1, 2020, we reorganized our operations to consist of a single resource-renewal focused operation by combining our larger-scale recycling and commodity brokerage operations along with our organics services and large scale commercial and industrial services into our Resource Solutions operating segment. We continue to manage our solid waste operations on a geographic basis through two regional operating segments, the Eastern and Western regions, each of which provides a full range of solid waste services. Legal, tax, information technology, human resources, certain finance and accounting and other administrative functions are included in our Corporate Entities operating segment. Segment information reported in the fiscal years ended December 31, 2019 (:fiscal year 2019") and 2018 ("fiscal year 2018"), and as of December 31, 2019 has been reclassified to conform with the fiscal year ended December 31, 2020 ("fiscal year 2020") and as of December 31, 2020 presentation. The accompanying consolidated financial statements, which include the accounts of the Parent, our wholly-owned subsidiaries and any partially owned entities over which we have a controlling financial interest, have been prepared in accordance with generally accepted accounting principles in the United States (“GAAP”) pursuant to the rules and regulations of the Securities and Exchange Commission (“SEC”). All significant intercompany accounts and transactions are eliminated in consolidation. Investments in entities in which we do not have a controlling financial interest are accounted for under either the equity method or the cost method of accounting, as appropriate. Recent Events With the global outbreak of the novel coronavirus ("COVID-19") and the declaration of a pandemic by the World Health Organization in March 2020, the U.S. Government and all of the states in which we operate have declared the waste services industry as an essential services provider and as a result we are committed to continue to operate and provide our full breadth of services. We have prioritized the safety and well-being of our employees by strictly adhering to recommendations of the Centers for Disease Control and Prevention as well as executive orders of the states in which we operate. The COVID-19 pandemic has caused, and will continue to cause, economic disruption across our geographic footprint and has adversely affected, and is expected to continue to adversely affect, our business. The COVID-19 pandemic negatively impacted our revenues starting at the end of the first quarter of fiscal year 2020, as many small business and construction collection customers required service level changes and volumes into our landfills declined due to lower economic activity. Even with the continued negative impact of the COVID-19 pandemic, we did experience improved demand for services as local economies started to reopen as allowed by State Governments. This positive trend continued through December 31, 2020, as additional small business collection customers increased service levels, construction activity continued to rebound, and overall higher economic activity across the northeast led to higher landfill volumes. Despite these positive trends, our collection and disposal operations were negatively impacted by lower volumes attributable to the COVID-19 pandemic in fiscal year 2020, extending into the first quarter of fiscal year 2021. The COVID-19 pandemic has negatively impacted and will continue to impact our business in other ways, as we have experienced and continue to experience increased costs in response to the COVID-19 pandemic, including, but not limited to, higher costs associated with providing a safe working environment for our employees (such as increased costs associated with the protection of our employees, including costs for additional safety equipment, hygiene products and enhanced facility cleaning), potential employee layoffs or furloughs, employee impacts from illness, supporting a remote administration workforce, community response measures, the inability of customers to continue to pay for services, and temporary closures of our facilities or the facilities of our customers. In early September 2020, we also paid a special bonus to all our hourly employees (both frontline and administrative) to recognize their hard work and commitment to safety, environmental compliance and high customer service standards as essential service providers during the COVID-19 pandemic. We have taken measures to reduce costs in other areas and preserve liquidity during this period of uncertainty. As of the date of this filing, we are unable to determine or predict the nature, duration or scope of the overall impact that the COVID-19 pandemic will have on our business, results of operations, liquidity and capital resources. For further information regarding the impact of the COVID-19 pandemic on us, see Item 1A, “Risk Factors” included in this Annual Report on Form 10-K.