Condensed Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012
Cash Flows from Operating Activities:
Net income	$ 209,258	$ 102,789
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation, depletion and amortization	129,838	127,994
Amortization of financing costs	3,332	912
Amortization of net loss on treasury lock	4,242	1,574
Share-based compensation expense	9,956	8,477
Deferred income tax provision	3,604	173,696
Alternative fuel mixture credits	76,280	(72,436)
Loss on disposals of property, plant and equipment	5,147	4,668
Loss on early extinguishment of debt		21,296
Pension and postretirement benefits	10,600	(7,775)
Other, net	(496)	(3,354)
(Increase) decrease in assets -
Accounts receivable	(57,583)	(52,528)
Inventories	1,875	(4,217)
Prepaid expenses and other current assets	(9,196)	(8,587)
Increase (decrease) in liabilities -
Accounts payable	46,418	(10,650)
Accrued liabilities	(13,107)	(30,048)
Net cash provided by operating activities	420,168	251,811
Cash Flows from Investing Activities:
Additions to property, plant and equipment	(130,410)	(94,396)
Acquisition of business		(35,393)
Treasury grant proceeds		57,399
Additions to other long term assets	(2,459)	(1,181)
Proceeds from disposals of property, plant and equipment	350	25
Net cash used for investing activities	(132,519)	(73,546)
Cash Flows from Financing Activities:
Proceeds on long-term debt		397,044
Payments on long-term debt	(11,967)	(433,202)
Financing costs paid	(8,220)	(821)
Settlement of treasury lock		(65,500)
Common stock dividends paid	(69,883)	(68,776)
Repurchases of common stock	(7,799)	(41,524)
Proceeds from exercise of stock options	2,756	16,121
Excess tax benefits from share-based awards	7,539	2,986
Shares withheld to cover employee restricted stock taxes	(10,873)
Net cash used for financing activities	(98,447)	(193,672)
Net increase (decrease) in cash and cash equivalents	189,202	(15,407)
Cash and cash equivalents, beginning of period	207,393	156,313
Cash and cash equivalents, end of period	$ 396,595	$ 140,906