CONSOLIDATED BALANCE SHEETS (USD $) In Thousands, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
Current assets:
Cash and cash equivalents	$ 248,635	$ 229,836
Marketable securities	11,787	11,778
Accounts receivable, net of allowances aggregating $17,824 and $11,125, respectively	603,054	541,423
Unbilled accounts receivable	42,122	27,072
Deferred costs	17,097	6,888
Prepaid expenses and other current assets	41,880	75,778
Inventories and supplies	155,301	171,441
Deferred tax assets	21,898	22,577
Total current assets	1,141,774	1,086,793
Property, plant and equipment, net	1,615,427	1,531,763
Other assets:
Long-term investments	4,352	4,354
Deferred financing costs	21,565	21,657
Goodwill	590,152	593,771
Permits and other intangibles, net	567,776	572,817
Other	15,806	14,651
Total other assets	1,199,651	1,207,250
Total assets	3,956,852	3,825,806
Current liabilities:
Current portion of capital lease obligations	1,973	5,092
Accounts payable	321,097	256,468
Deferred revenue	61,912	50,942
Accrued expenses	256,813	232,429
Current portion of closure, post-closure and remedial liabilities	27,737	24,121
Total current liabilities	669,532	569,052
Other liabilities:
Closure and post-closure liabilities, less current portion of $7,512 and $8,791, respectively	39,982	45,457
Remedial liabilities, less current portion of $20,225 and $15,330, respectively	151,866	151,890
Long-term obligations	1,400,000	1,400,000
Capital lease obligations, less current portion	1,669	2,879
Deferred taxes, unrecognized tax benefits and other long-term liabilities	217,683	224,456
Total other liabilities	1,811,200	1,824,682
Common stock, $.01 par value:
Authorized 80,000,000; shares issued and outstanding 60,612,702 and 60,385,453 shares, respectively	606	604
Shares held under employee participation plan	(469)	(469)
Additional paid-in capital	893,822	880,979
Accumulated other comprehensive income	12,070	49,632
Accumulated earnings	570,091	501,326
Total stockholders’ equity	1,476,120	1,432,072
Total liabilities and stockholders’ equity	$ 3,956,852	$ 3,825,806