INCOME TAXES - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended			6 Months Ended	12 Months Ended	6 Months Ended	12 Months Ended
	Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010	Dec. 31, 2010	Jun. 30, 2011 Internal Revenue Service (IRS)	Dec. 31, 2010 Internal Revenue Service (IRS)	Jun. 30, 2011 State and Local Jurisdiction	Dec. 31, 2010 State and Local Jurisdiction
Income Taxes [Line Items]
Estimated effective tax rate for the year ending December 31, 2011			39.60%
Effective income tax rate			20.60%	59.50%
Liability for uncertain tax positions, exclusive of interest and penalties	$ 130.1		$ 130.1		$ 130.1
Unrecognized tax benefits that, if recognized, would impact the effective tax rate	130.1		130.1
Possible decrease of acquisition related reserves and some other reserves in the liability for uncertain tax positions in the next six months	(17.9)		(17.9)
Expense (benefit) of interest and penalties on uncertain tax positions	0.2	0	0.7	(1.7)
Accrued interest and penalties associated with liabilities for unrecognized tax positions	8.1		8.1		7.3
Open tax years						Federal income tax returns for Covanta Energy are closed for the years through 2003. However, to the extent net operating loss carryforwards ("NOLs") are utilized from earlier years, federal income tax returns for Covanta Holding Corporation, formerly known as Danielson Holding Corporation, are still open.		State income tax returns are generally subject to examination for a period of three to five years after the filing of the respective return. The state impact of any federal changes remains subject to examination by various states for a period of up to one year after formal notification to the states. We have various state income tax returns in the process of examination, administrative appeals or litigation.
Consolidated net operating loss carryforwards							396.9		188.8
Net operating loss expirations							in various amounts from December 31, 2023 through December 31, 2030		between 2011 and 2027
Capital loss carryforwards									0.2
Capital loss expirations									in 2013
Additional federal credit carryforwards, including production tax credits and minimum tax credits							45.6
Valuation allowance on deferred tax assets					$ 19.8