CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Cash flows from operating activities:
Net income	$ 32,015	$ 22,730
Adjustments to reconcile net income to net cash from operating activities:
Depreciation and amortization	36,831	25,460
Allowance for doubtful accounts	203	205
Amortization of deferred financing costs and debt discount	367	614
Accretion of environmental liabilities	2,416	2,389
Changes in environmental liability estimates	(646)	(260)
Deferred income taxes	(269)	486
Stock-based compensation	2,141	1,744
Excess tax benefit of stock-based compensation	(713)	(1,105)
Income tax benefit related to stock option exercises	713	1,105
Other expense	299	455
Environmental expenditures	(1,722)	(2,340)
Changes in assets and liabilities, net of acquisitions
Accounts receivable	(12,955)	(10,341)
Other current assets	(1,890)	2,949
Accounts payable	(4,302)	(6,876)
Other current liabilities	(22,935)	(22,359)
Net cash from operating activities	29,553	14,856
Cash flows from investing activities:
Additions to property, plant and equipment	(27,661)	(34,115)
Proceeds from sales of fixed assets	425	1,013
Acquisitions, net of cash acquired	(8,751)	(2,152)
Additions to intangible assets, including costs to obtain or renew permits	(425)	(322)
Purchase of available for sale securities	(4,468)	0
Proceeds from sales of marketable securities	0	388
Other	5,120	0
Net cash used in investing activities	(35,760)	(35,188)
Cash flows from financing activities:
Change in uncashed checks	(13,576)	(5,216)
Proceeds from exercise of stock options	30	39
Remittance of shares, net	0	(1,784)
Proceeds from employee stock purchase plan	1,238	699
Deferred financing costs paid	0	(5,628)
Payments on capital leases	(2,166)	(1,690)
Distribution of cash earned on employee participation plan	(38)	(189)
Excess tax benefit of stock-based compensation	713	1,105
Issuance of senior secured notes, including premium	0	261,250
Net cash from financing activities	(13,799)	248,586
Effect of exchange rate change on cash	810	1,299
(Decrease) increase in cash and cash equivalents	(19,196)	229,553
Cash and cash equivalents, beginning of period	260,723	302,210
Cash and cash equivalents, end of period	241,527	531,763
Cash payments for interest and income taxes:
Interest paid	20,811	10,789
Income taxes paid	1,050	8,274
Non-cash investing and financing activities:
Property, plant and equipment accrued	$ 19,766	$ 17,571