CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Cash flows from operating activities:
Net income	$ 95,566	$ 129,674	$ 127,252
Adjustments to reconcile net income to net cash from operating activities:
Depreciation and amortization	264,449	161,646	122,663
Pre-tax, non-cash acquisition accounting inventory adjustments	13,559	0	0
Allowance for doubtful accounts	7,933	1,213	759
Amortization of deferred financing costs and debt discount	3,301	1,793	1,572
Accretion of environmental liabilities	11,541	9,917	9,680
Changes in environmental liability estimates	(3,682)	(8,458)	(2,840)
Deferred income taxes	31,119	34,163	37,836
Other (income) expense	(1,705)	802	(3,048)
Stock-based compensation	8,946	7,494	8,164
Excess tax benefit of stock-based compensation	(1,409)	(2,556)	(3,352)
Income tax benefit related to stock option exercises	1,399	2,546	3,347
Write-off of deferred financing costs and debt (premium) discount	0	5,341	0
Environmental expenditures	(19,416)	(11,191)	(11,319)
Changes in assets and liabilities:
Accounts receivable	(53,735)	54,373	(65,210)
Inventories and supplies	(1,144)	(12,871)	(11,696)
Other current assets	20,379	9,334	(25,065)
Accounts payable	37,117	5,930	(8,116)
Other current and long-term liabilities	1,621	(64,785)	(1,096)
Net cash from operating activities	415,839	324,365	179,531
Cash flows from investing activities:
Additions to property, plant and equipment	(280,207)	(197,397)	(148,513)
Proceeds from sales of fixed assets	4,699	8,125	6,794
Acquisitions, net of cash acquired	(63,264)	(1,373,921)	(336,960)
Additions to intangible assets including costs to obtain or renew permits	(6,740)	(4,046)	(2,927)
Purchase of marketable securities	0	(10,517)	0
Proceeds from sales of marketable securities	0	0	425
Proceeds from sale of long-term investments	0	0	1,000
Other	0	5,120	0
Net cash used in investing activities	(345,512)	(1,572,636)	(480,181)
Cash flows from financing activities:
Change in uncashed checks	12,268	(12,070)	9,822
Proceeds from exercise of stock options	400	288	1,350
Remittance of shares, net	(731)	(2,912)	(4,061)
Excess tax benefit of stock-based compensation	1,409	2,556	3,352
Deferred financing costs paid	(2,504)	(19,056)	(8,463)
Proceeds from employee stock purchase plan	7,425	6,196	3,516
Payments on capital leases	(4,891)	(6,599)	(7,837)
Proceeds from issuance of common stock, net	0	369,520	0
Principal payments on debt	0	(520,000)	0
Distribution of cash earned on employee participation plan	0	(55)	(189)
Issuance of senior unsecured notes, at par	0	1,400,000	0
Issuance of senior secured notes, including premium	0	0	261,250
Issuance costs related to issuances of common stock	(250)	0	0
Net cash from financing activities	13,126	1,217,868	258,740
Effect of exchange rate change on cash	(3,216)	(484)	423
Increase (decrease) in cash and cash equivalents	80,237	(30,887)	(41,487)
Cash and cash equivalents, beginning of year	229,836	260,723	302,210
Cash and cash equivalents, end of year	310,073	229,836	260,723
Cash payments for interest and income taxes:
Interest paid	75,627	41,817	31,201
Income taxes (received) paid	(8,162)	13,179	48,725
Non-cash investing and financing activities:
Property, plant and equipment accrued	33,214	29,788	18,682
Transfer of inventory to property, plant and equipment	11,369	0	0
Accrued working capital adjustments	0	(750)	3,694
Assets acquired through capital lease	$ 0	$ 154	$ 1,807