UNAUDITED CONSOLIDATED BALANCE SHEETS (Parenthetical) (USD $) In Thousands, except Share data, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Statement of Financial Position [Abstract]
Account Receivable, allowances aggregating	$ 26,358	$ 25,661
Closure and post-closure liabilities, current portion	8,272	4,999
Remedial liabilities, current portion	$ 16,852	$ 17,092
Common stock, par value	$ 0.01	$ 0.01
Common stock, authorized shares	80,000,000us-gaap_CommonStockSharesAuthorized	80,000,000us-gaap_CommonStockSharesAuthorized
Common stock, issued shares	58,661,384us-gaap_CommonStockSharesIssued	58,903,482us-gaap_CommonStockSharesIssued
Common stock, outstanding shares	58,661,384us-gaap_CommonStockSharesOutstanding	58,903,482us-gaap_CommonStockSharesOutstanding

The amount of estimated costs accrued as of the balance sheet date to comply with regulatory requirements pertaining to the retirement of a waste management facility (such as a landfill or waste treatment facility). Represents the portion that will be paid within one year or the normal operating cycle, if longer.

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Carrying value of the obligation (known or estimated) arising from requirements to perform activities to remediate one or more sites, payable in twelve months or in the next operating cycle if longer.

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