CONSOLIDATED BALANCE SHEETS (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Current assets:
Cash and cash equivalents	$ 310,073	$ 229,836
Marketable securities	12,435	11,778
Accounts receivable, net of allowances aggregating $18,106 and $11,125, respectively	579,394	546,136
Unbilled accounts receivable	26,568	27,072
Deferred costs	16,134	6,888
Inventories and supplies	152,096	176,478
Prepaid expenses and other current assets	41,962	75,765
Deferred tax assets	32,517	21,306
Total current assets	1,171,179	1,095,259
Property, plant and equipment, net	1,602,170	1,533,053
Other assets:
Deferred financing costs	20,860	21,657
Goodwill	570,960	579,715
Permits and other intangibles, net	569,973	590,044
Other	18,536	18,358
Total other assets	1,180,329	1,209,774
Total assets	3,953,678	3,838,086
Current liabilities:
Current portion of capital lease obligations	1,329	5,092
Accounts payable	316,462	257,911
Deferred revenue	55,454	50,973
Accrued expenses	236,829	246,354
Current portion of closure, post-closure and remedial liabilities	29,471	28,336
Total current liabilities	639,545	588,666
Other liabilities:
Closure and post-closure liabilities, less current portion of $5,884 and $8,791, respectively	41,201	35,256
Remedial liabilities, less current portion of $23,587 and $19,545, respectively	148,911	163,801
Long-term obligations	1,400,000	1,400,000
Capital lease obligations, less current portion	1,435	2,879
Deferred taxes, unrecognized tax benefits and other long-term liabilities	246,947	215,412
Total other liabilities	1,838,494	1,817,348
Commitments and contingent liabilities
Stockholders' equity:
Authorized 80,000,000 shares; issued and outstanding 60,672,180 and 60,385,453 shares, respectively	607	604
Shares held under employee participation plan	(469)	(469)
Additional paid-in capital	898,165	880,979
Accumulated other comprehensive (loss) income	(19,556)	49,632
Accumulated earnings	596,892	501,326
Total stockholders' equity	1,475,639	1,432,072
Total liabilities and stockholders' equity	$ 3,953,678	$ 3,838,086