CONSOLIDATED BALANCE SHEETS (USD $) In Thousands, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011
Current assets:
Cash and cash equivalents	$ 296,758	$ 260,723
Marketable securities	9,701	111
Accounts receivable, net of allowances aggregating $11,239 and $12,683, respectively	397,453	449,553
Unbilled accounts receivable	30,173	29,385
Deferred costs	7,273	5,903
Prepaid expenses and other current assets	49,763	73,349
Supplies inventories	57,782	56,242
Deferred tax assets	16,605	16,602
Total current assets	865,508	891,868
Property, plant and equipment:
Land	37,171	37,185
Asset retirement costs (non-landfill)	2,544	2,529
Landfill assets	61,056	58,466
Buildings and improvements	193,717	189,445
Camp equipment	130,340	110,242
Vehicles	259,315	231,980
Equipment	768,502	729,154
Furniture and fixtures	3,988	3,759
Construction in progress	39,641	24,522
Property, plant and equipment, gross	1,496,274	1,387,282
Less-accumulated depreciation and amortization	541,234	483,335
Total property, plant and equipment, net	955,040	903,947
Other assets:
Long-term investments	4,326	4,245
Deferred financing costs	12,152	13,607
Goodwill	135,962	122,392
Permits and other intangibles, net of accumulated amortization of $80,000 and $72,544, respectively	138,622	139,644
Other	10,604	10,100
Total other assets	301,666	289,988
Total assets	2,122,214	2,085,803
Current liabilities:
Current portion of capital lease obligations	6,322	8,310
Accounts payable	172,657	178,084
Deferred revenue	32,015	32,297
Accrued expenses	130,526	147,992
Current portion of closure, post-closure and remedial liabilities	19,801	15,059
Total current liabilities	361,321	381,742
Other liabilities:
Closure and post-closure liabilities, less current portion of $6,407 and $3,3885, respectively	29,140	30,996
Remedial liabilities, less current portion of $13,394 and $11,174, respectively	118,563	124,146
Long-term obligations	523,481	524,203
Capital lease obligations, less current portion	4,482	6,375
Unrecognized tax benefits and other long-term liabilities	124,327	117,354
Total other liabilities	799,993	803,074
Common stock, $.01 par value:
Authorized 80,000,000; shares issued and outstanding 53,319,029 and 53,182,859 shares, respectively	533	532
Shares held under employee participation plan	(469)	(469)
Additional paid-in capital	504,667	497,919
Accumulated other comprehensive income	29,076	31,353
Accumulated earnings	427,093	371,652
Total stockholders' equity	960,900	900,987
Total liabilities and stockholders' equity	$ 2,122,214	$ 2,085,803