INCOME TAXES DEFERRED TAX ASSET AND LIABILITIES (Details) (USD $)	12 Months Ended
	Dec. 31, 2011		Dec. 31, 2010		Dec. 31, 2009
Components of Deferred Tax Assets [Abstract]
Workers compensation accrual	$ 5,011,000		$ 4,750,000
Provision for doubtful accounts	4,803,000		8,191,000
Closure, post-closure and remedial liabilities	31,082,000		35,885,000
Accrued expenses	13,635,000		11,960,000
Accrued compensation	2,279,000		1,394,000
Net operating loss carryforwards(1)	23,663,000	[1]	2,246,000	[1]
Tax credit carryforwards(2)	19,977,000	[2]	17,324,000	[2]
Uncertain tax positions accrued interest and federal benefit	11,462,000		10,341,000
Stock-based compensation	1,884,000		2,749,000
Other	4,421,000		4,359,000
Total deferred tax asset	118,217,000		99,199,000
Deferred tax liabilities:
Property, plant and equipment	(114,115,000)		(64,626,000)
Permits and customer databases	(20,547,000)		(19,412,000)
Total deferred tax liability	134,662,000		84,038,000
Deferred Tax Assets (Liabilities), Net	(16,445,000)		15,161,000
Less valuation allowance	(11,473,000)		(12,919,000)
Net deferred tax (liability) asset	27,918,000		(2,242,000)
Deferred Tax Assets, Operating Loss Carryforwards, State and Local	18,700,000
Deferred Tax Assets, Operating Loss Carryforwards, Domestic	15,300,000
Deferred Tax Assets, Operating Loss Carryforwards, Foreign	800,000
Valuation Allowance, Amount	11,500,000		12,900,000
Deferred Tax Assets, Tax Credit Carryforwards, Foreign	19,977,000
Increase (Decreade) Tax Benefit From Stock Options Exercised	16,200,000
Income tax benefit related to stock option exercises	3,347,000		1,739,000		474,000
2012
Deferred tax liabilities:
Valuation Allowance, Amount	788,000
2013
Deferred tax liabilities:
Valuation Allowance, Amount	4,828,000
2014
Deferred tax liabilities:
Valuation Allowance, Amount	3,687,000
2015
Deferred tax liabilities:
Valuation Allowance, Amount	682,000
2016
Deferred tax liabilities:
Valuation Allowance, Amount	1,164,000
Thereafter
Deferred tax liabilities:
Valuation Allowance, Amount	8,828,000
Foreign Country [Member]
Deferred tax liabilities:
Operating Loss Carryforwards	$ 65,800,000

[1] As of December 31, 2011, the net operating loss carryforwards included (i) state net operating loss carryovers of $18.7 million which begin to expire in 2019 and federal net operating loss carryforwards of $15.3 million which begin to expire in 2028, and (ii) Canadian net operating losses of $65.8 million which begin to expire in 2026 and other foreign net operating losses of $0.8 million which begin to

[2] As of December 31, 2011, foreign tax credit carryforwards of $20.0 million expire between 2012 and 2021 as follows: