Condensed Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011
Cash Flows from Operating Activities:
Net income	$ 102,789	$ 118,562
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation, depletion and amortization	127,994	121,033
Amortization of financing costs	912	361
Amortization of net loss on treasury lock	1,574	(1,385)
Share-based compensation expense	8,477	7,191
Deferred income tax provision	31,445	21,377
Cellulosic biofuel producer credit reduction	142,251
Alternative fuel mixture credits	(72,436)
Loss on disposals of property, plant and equipment	4,668	6,970
Loss on early extinguishment of debt	21,296
Pension and postretirement benefits	(7,775)	2,619
Other, net	(3,354)	(3,752)
Increase in assets -
Accounts receivable	(52,528)	(39,374)
Inventories	(4,217)	(1,346)
Prepaid expenses and other current assets	(8,587)	(5,269)
Increase (decrease) in liabilities -
Accounts payable	(10,650)	22,474
Accrued liabilities	(30,048)	(12,644)
Net cash provided by operating activities	251,811	236,817
Cash Flows from Investing Activities:
Additions to property, plant and equipment	(94,396)	(214,958)
Treasury grant proceeds	57,399
Acquisitions of businesses	(35,393)	(35,643)
Additions to other long term assets	(1,181)	(10,973)
Proceeds from disposals of property, plant and equipment	25	427
Net cash used for investing activities	(73,546)	(261,147)
Cash Flows from Financing Activities:
Proceeds from long-term debt	397,044
Payments on long-term debt	(433,202)	(498)
Financing costs paid	(821)
Settlement of treasury lock	(65,500)	9,910
Common stock dividends paid	(68,776)	(56,053)
Repurchases of common stock	(41,524)	(93,425)
Proceeds from exercise of stock options	16,121	6,870
Excess tax benefits from share-based awards	2,986	1,087
Net cash used for financing activities	(193,672)	(132,109)
Net decrease in cash and cash equivalents	(15,407)	(156,439)
Cash and cash equivalents, beginning of period	156,313	196,556
Cash and cash equivalents, end of period	$ 140,906	$ 40,117