CONSOLIDATED BALANCE SHEETS (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Current assets:
Cash and cash equivalents	$ 229,836	$ 260,723
Marketable securities	11,778	111
Accounts receivable, net of allowances aggregating $11,125 and $12,683, respectively	541,423	449,553
Unbilled accounts receivable	27,072	29,385
Deferred costs	6,888	5,903
Prepaid expenses and other current assets	75,778	73,349
Inventories and supplies	171,441	56,242
Deferred tax assets	22,577	16,602
Total current assets	1,086,793	891,868
Property, plant and equipment, net	1,531,763	903,947
Other assets:
Long-term investments	4,354	4,245
Deferred financing costs	21,657	13,607
Goodwill	593,771	122,392
Permits and other intangibles, net	572,817	139,644
Other	14,651	10,100
Total other assets	1,207,250	289,988
Total assets	3,825,806	2,085,803
Current liabilities:
Current portion of capital lease obligations	5,092	8,310
Accounts payable	256,468	178,084
Deferred revenue	50,942	32,297
Accrued expenses	232,429	147,992
Current portion of closure, post-closure and remedial liabilities	24,121	15,059
Total current liabilities	569,052	381,742
Other liabilities:
Closure and post-closure liabilities, less current portion of $8,791 and $3,885, respectively	45,457	30,996
Remedial liabilities, less current portion of $15,330 and $11,174, respectively	151,890	124,146
Long-term obligations	1,400,000	524,203
Capital lease obligations, less current portion	2,879	6,375
Deferred taxes, unrecognized tax benefits and other long-term liabilities	224,456	117,354
Total other liabilities	1,824,682	803,074
Stockholders' equity:
Authorized 80,000,000 shares; issued and outstanding 60,385,453 and 53,182,859 shares, respectively	604	532
Shares held under employee participation plan	(469)	(469)
Additional paid-in capital	880,979	497,919
Accumulated other comprehensive income	49,632	31,353
Accumulated earnings	501,326	371,652
Total stockholders' equity	1,432,072	900,987
Total liabilities and stockholders' equity	$ 3,825,806	$ 2,085,803