CONSOLIDATED BALANCE SHEETS (USD $) In Thousands, unless otherwise specified	Mar. 31, 2012	Dec. 31, 2011
Current assets:
Cash and cash equivalents	$ 241,527	$ 260,723
Marketable securities	4,997	111
Accounts receivable, net of allowances aggregating $13,575 and $12,683, respectively	463,431	449,553
Unbilled accounts receivable	29,904	29,385
Deferred costs	5,787	5,903
Prepaid expenses and other current assets	62,118	73,349
Supplies inventories	57,695	56,242
Deferred tax assets	16,426	16,602
Total current assets	881,885	891,868
Property, plant and equipment:
Land	37,377	37,185
Asset retirement costs (non-landfill)	2,552	2,529
Landfill assets	57,743	58,466
Buildings and improvements	192,514	189,445
Camp equipment	112,482	110,242
Vehicles	248,361	231,980
Equipment	749,395	729,154
Furniture and fixtures	3,832	3,759
Construction in progress	31,827	24,522
Property, plant and equipment, gross	1,436,083	1,387,282
Less-accumulated depreciation and amortization	517,399	483,335
Total property, plant and equipment, net	918,684	903,947
Other assets:
Long-term investments	4,245	4,245
Deferred financing costs	12,872	13,607
Goodwill	125,723	122,392
Permits and other intangibles, net of accumulated amortization of $76,989 and $72,544, respectively	138,967	139,644
Other	10,519	10,100
Total other assets	292,326	289,988
Total assets	2,092,895	2,085,803
Current liabilities:
Current portion of capital lease obligations	7,365	8,310
Accounts payable	172,551	178,084
Deferred revenue	29,157	32,297
Accrued expenses	114,501	147,992
Current portion of closure, post-closure and remedial liabilities	18,653	15,059
Total current liabilities	342,227	381,742
Other liabilities:
Closure and post-closure liabilities, less current portion of $5,538 and $3,3885, respectively	28,560	30,996
Remedial liabilities, less current portion of $13,115 and $11,174, respectively	121,885	124,146
Long-term obligations	523,833	524,203
Capital lease obligations, less current portion	5,406	6,375
Unrecognized tax benefits and other long-term liabilities	119,706	117,354
Total other liabilities	799,390	803,074
Common stock, $.01 par value:
Authorized 80,000,000; shares issued and outstanding 53,256,146 and 53,182,859 shares, respectively	533	532
Shares held under employee participation plan	(469)	(469)
Additional paid-in capital	501,014	497,919
Accumulated other comprehensive income	46,533	31,353
Accumulated earnings	403,667	371,652
Total stockholders' equity	951,278	900,987
Total liabilities and stockholders' equity	$ 2,092,895	$ 2,085,803