CONSOLIDATED BALANCE SHEETS (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Current assets:
Cash and cash equivalents	$ 222,104	$ 229,836
Marketable securities	10,905	11,778
Accounts receivable, net of allowances aggregating $13,531 and $11,125, respectively	563,691	541,423
Unbilled accounts receivable	32,220	27,072
Deferred costs	16,987	6,888
Prepaid expenses and other current assets	57,828	75,778
Inventories and supplies	144,476	171,441
Deferred tax assets	25,371	22,577
Total current assets	1,073,582	1,086,793
Property, plant and equipment, net	1,549,806	1,531,763
Other assets:
Long-term investments	4,354	4,354
Deferred financing costs	23,239	21,657
Goodwill	572,406	593,771
Permits and other intangibles, net	566,910	572,817
Other	13,081	14,651
Total other assets	1,179,990	1,207,250
Total assets	3,803,378	3,825,806
Current liabilities:
Current portion of capital lease obligations	4,320	5,092
Accounts payable	263,564	256,468
Deferred revenue	62,162	50,942
Accrued expenses	212,424	232,429
Current portion of closure, post-closure and remedial liabilities	21,575	24,121
Total current liabilities	564,045	569,052
Other liabilities:
Closure and post-closure liabilities, less current portion of $3,683 and $8,791, respectively	41,670	45,457
Remedial liabilities, less current portion of $17,892 and $15,330, respectively	156,676	151,890
Long-term obligations	1,400,000	1,400,000
Capital lease obligations, less current portion	2,154	2,879
Deferred taxes, unrecognized tax benefits and other long-term liabilities	215,365	224,456
Total other liabilities	1,815,865	1,824,682
Common stock, $.01 par value:
Authorized 80,000,000; shares issued and outstanding 60,491,452 and 60,385,453 shares, respectively	605	604
Shares held under employee participation plan	(469)	(469)
Additional paid-in capital	885,733	880,979
Accumulated other comprehensive income	25,771	49,632
Accumulated earnings	511,828	501,326
Total stockholders’ equity	1,423,468	1,432,072
Total liabilities and stockholders’ equity	$ 3,803,378	$ 3,825,806