CONSOLIDATED BALANCE SHEETS (USD $) In Thousands, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010
Current assets:
Cash and cash equivalents	$ 260,723	$ 302,210
Marketable securities	111	3,174
Accounts receivable, net of allowances aggregating $12,683 and $23,704, respectively	449,553	332,678
Unbilled accounts receivable	29,385	19,117
Deferred costs	5,903	6,891
Prepaid expenses and other current assets	73,349	28,939
Supplies inventories	56,242	44,546
Deferred tax assets	16,602	14,982
Total current assets	891,868	752,537
Property, plant and equipment:
Land	37,185	31,654
Asset retirement costs (non-landfill)	2,529	2,242
Landfill assets	58,466	54,519
Buildings and improvements	189,445	147,285
Camp equipment	110,242	62,717
Vehicles	231,980	162,397
Equipment	729,154	537,937
Furniture and fixtures	3,759	2,293
Construction in progress	24,522	33,005
Property, plant and equipment, gross	1,387,282	1,034,049
Less-accumulated depreciation and amortization	483,335	378,655
Total property, plant and equipment, net	903,947	655,394
Other assets:
Long-term investments	4,245	5,437
Deferred financing costs	13,607	7,768
Goodwill	122,392	60,252
Permits and other intangibles, net of accumulated amortization of $72,544 and $60,633, respectively	139,644	114,400
Other	10,100	6,687
Total other assets	289,988	194,544
Total assets	2,085,803	1,602,475
Current liabilities:
Current portion of capital lease obligations	8,310	7,954
Accounts payable	178,084	136,978
Deferred revenue	32,297	30,745
Accrued expenses	147,992	116,089
Current portion of closure, post-closure and remedial liabilities	15,059	14,518
Total current liabilities	381,742	306,284
Other liabilities:
Closure and post-closure liabilities, less current portion of $3,885 and $5,849, respectively	30,996	32,830
Remedial liabilities, less current portion of $11,174 and $8,669, respectively	124,146	128,944
Long-term obligations	524,203	264,007
Capital lease obligations, less current portion	6,375	6,839
Unrecognized tax benefits and other long-term liabilities	117,354	82,744
Total other liabilities	803,074	515,364
Common stock, $.01 par value:
Authorized 80,000,000 shares issued and outstanding 53,182,859 and 52,772,392 shares, respectively	532	528
Treasury stock	0	(2,467)
Shares held under employee participation plan	(469)	(777)
Additional paid-in capital	497,919	488,384
Accumulated other comprehensive income	31,353	50,759
Accumulated earnings	371,652	244,400
Total stockholders' equity	900,987	780,827
Total liabilities and stockholders' equity	$ 2,085,803	$ 1,602,475