UNAUDITED CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Statement of Financial Position [Abstract]
Account Receivable, allowances aggregating	$ 30,271	$ 25,661
Closure and post-closure liabilities, current portion	5,403	4,999
Remedial liabilities, current portion	$ 16,499	$ 17,092
Common stock, par value	$ 0.01	$ 0.01
Common stock, authorized shares	80,000,000	80,000,000
Common stock, issued shares	57,664,992	58,903,482
Common stock, outstanding shares	57,664,992	58,903,482