CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Cash flows from operating activities:
Net income	$ 127,252	$ 130,515	$ 36,686
Adjustments to reconcile net income to net cash from operating activities:
Depreciation and amortization	122,663	92,473	64,898
Allowance for doubtful accounts	759	1,043	1,006
Amortization of deferred financing costs and debt discount	1,572	2,921	1,997
Accretion of environmental liabilities	9,680	10,307	10,617
Changes in environmental liability estimates	(2,840)	(8,328)	(4,657)
Deferred income taxes	37,836	4,919	4,830
Other (income) expense	(3,048)	(2,795)	(259)
Stock-based compensation	8,164	7,219	968
Excess tax benefit of stock-based compensation	(3,352)	(1,751)	(481)
Income tax benefit related to stock option exercises	3,347	1,739	474
Gains on sales of businesses	0	(2,678)	0
Write-off deferred financing costs and debt discount	0	1,394	1,851
Environmental expenditures	(11,319)	(10,236)	(8,617)
Changes in assets and liabilities, net of acquisitions
Accounts receivable	(65,210)	(49,411)	(11,429)
Other current assets	(36,761)	(10,550)	1,093
Accounts payable	(8,116)	38,553	5,050
Other current liabilities	(1,096)	18,774	(10,757)
Net cash from operating activities	179,531	224,108	93,270
Cash flows from investing activities:
Additions to property, plant and equipment	(148,513)	(116,450)	(62,244)
Acquisitions, net of cash acquired	336,960	14,646	54,476
Additions to intangible assets, including costs to obtain or renew permits	(2,927)	(4,204)	(2,228)
Purchase of marketable securities	0	(2,127)	0
Purchase of investment securities	0	(10,506)	0
Proceeds from sales of marketable securities	425	3,557	105
Proceeds from sales of fixed assets and assets held for sale	6,794	16,053	452
Proceeds from insurance settlement	0	1,336	0
Proceeds from sale of long-term investments	1,000	1,300	0
Net cash used in investing activities	(480,181)	(125,687)	(118,391)
Cash flows from financing activities:
Change in uncashed checks	9,822	(1,266)	4,034
Proceeds from exercise of stock options	1,350	862	430
Remittance of shares, net	(4,061)	(399)	(415)
Excess tax benefit of stock-based compensation	3,352	1,751	481
Deferred financing costs paid	(8,463)	(353)	(10,473)
Proceeds from employee stock purchase plan	3,516	2,449	2,315
Payments on capital leases	(7,837)	(5,126)	(1,118)
Payment on acquired debt	0	0	(230,745)
Principal payment on debt and acquired capital leases	0	(30,000)	(53,032)
Distribution of cash earned on employee participation plan	(189)	(148)	0
Issuance of senior secured notes, net	261,250	0	292,107
Net cash from financing activities	258,740	(32,230)	3,584
Effect of exchange rate change on cash	423	2,473	5,559
Increase in cash and cash equivalents	(41,487)	68,664	(15,978)
Cash and cash equivalents, beginning of period	302,210	233,546	249,524
Cash and cash equivalents, end of period	260,723	302,210	233,546
Cash payments for interest and income taxes:
Interest paid	31,201	26,985	7,833
Income taxes paid	48,725	56,015	14,608
Non-cash investing and financing activities:
Property, plant and equipment accrued	18,682	7,844	908
Accrued Working Capital Adjustment	3,694	0	0
Assets acquired through capital lease	1,807	10,130	0
Issuance of Clean Harbors common stock for Eveready common shares	0	0	118,427
Issuance of acquisition-related common stock, net	$ 0	$ 1,015	$ 0