Document and Entity Information - shares	3 Months Ended
	Mar. 31, 2018	Apr. 30, 2018
Document Information [Line Items]
Entity Registrant Name	CASELLA WASTE SYSTEMS INC
Entity Central Index Key	0000911177
Current Fiscal Year End Date	--12-31
Entity Filer Category	Accelerated Filer
Document Type	10-Q
Document Period End Date	Mar. 31, 2018
Document Fiscal Year Focus	2018
Document Fiscal Period Focus	Q1
Amendment Flag	false
Trading Symbol	CWST
Class A Common Stock
Document Information [Line Items]
Entity Common Stock, Shares Outstanding		41,700,119
Class B Common Stock
Document Information [Line Items]
Entity Common Stock, Shares Outstanding		988,200