UNAUDITED CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Cash flows from operating activities:
Net income	$ 8,960	$ 10,502
Adjustments to reconcile net income to net cash from operating activities:
Depreciation and amortization	69,356	60,006
Pre-tax, non-cash acquisition accounting inventory adjustments	0	13,559
Allowance for doubtful accounts	2,086	1,823
Amortization of deferred financing costs and debt discount	824	846
Accretion of environmental liabilities	2,724	2,835
Changes in environmental liability estimates	(821)	(58)
Deferred income taxes	0	32
Stock-based compensation	2,278	1,887
Excess tax benefit of stock-based compensation	(117)	(1,227)
Income tax benefit related to stock option exercises	117	1,216
Other income	(4,178)	(525)
Environmental expenditures	(4,186)	(5,291)
Changes in assets and liabilities, net of acquisitions
Accounts receivable	3,741	(28,726)
Inventories and supplies	(1,709)	13,573
Other current assets	(30,532)	6,377
Accounts payable	(23,374)	(16,112)
Other current and long-term liabilities	(20,573)	(21,128)
Net cash from operating activities	4,596	39,589
Cash flows from investing activities:
Additions to property, plant and equipment	(75,005)	(72,249)
Proceeds from sales of fixed assets	876	921
Proceeds from sales of marketable securities	12,870	0
Acquisitions, net of cash acquired	0	(197)
Additions to intangible assets, including costs to obtain or renew permits	(1,075)	(725)
Net cash used in investing activities	(62,334)	(72,250)
Cash flows from financing activities:
Change in uncashed checks	21	26,419
Proceeds from exercise of stock options	0	397
Remittance of shares, net	(750)	(41)
Repurchases of common stock	(1,225)	0
Proceeds from employee stock purchase plan	2,141	1,546
Deferred financing costs paid	0	(2,318)
Payments on capital leases	(638)	(1,346)
Issuance costs related to 2012 issuance of common stock	0	(250)
Excess tax benefit of stock-based compensation	117	1,227
Net cash from financing activities	(334)	25,634
Effect of exchange rate change on cash	(2,994)	(705)
Decrease in cash and cash equivalents	(61,066)	(7,732)
Cash and cash equivalents, beginning of period	310,073	229,836
Cash and cash equivalents, end of period	249,007	222,104
Cash payments for interest and income taxes:
Interest paid	21,436	21,725
Income taxes paid	5,389	3,662
Non-cash investing and financing activities:
Property, plant and equipment accrued	26,715	21,722
Transfer of inventory to property, plant and equipment	$ 0	$ 11,369