CONSOLIDATED BALANCE SHEETS (Parenthetical) (USD $) In Thousands, except Share data, unless otherwise specified	Mar. 31, 2014	Dec. 31, 2013
Statement of Financial Position [Abstract]
Allowance for doubtful accounts receivable, current portion	$ 20,094	$ 18,106
Closure and post-closure liabilities, current portion	7,629	5,884
Remedial liabilities, current portion	$ 24,237	$ 23,587
Common Stock, Par or Stated Value Per Share (in USD per share)	$ 0.01	$ 0.01
Common Stock, Shares Authorized	80,000,000	80,000,000
Common Stock, Shares, Issued	60,717,774	60,672,180
Common Stock, Shares, Outstanding	60,717,774	60,672,180