Consolidated Statements of Income and Comprehensive Income (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended										12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011		Sep. 30, 2011		Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
SALES	$ 434,306	$ 408,988	$ 371,926	$ 355,780	$ 388,423		$ 385,091		$ 357,397	$ 357,731	$ 1,571,000	$ 1,488,642	$ 1,315,233
Costs and Expenses
Cost of sales											1,104,805	1,073,732	990,099
Selling and general expenses											68,397	66,541	67,102
Other operating income, net (Note 14)											(13,103)	(3,829)	(10,519)
Costs and Expenses, Total											1,160,099	1,136,444	1,046,682
Equity in income of New Zealand joint venture											550	4,088	1,033
OPERATING INCOME BEFORE GAIN ON SALE OF A PORTION OF INTEREST IN NEW ZEALAND JOINT VENTURE											411,451	356,286	269,584
Gain on sale of a portion of interest in New Zealand joint venture (Note 5)											0	0	12,367
OPERATING INCOME	115,678	113,174	98,590	84,009	81,325	[1]	108,310		79,073	87,578	411,451	356,286	281,951
Interest expense											(44,981)	(50,775)	(50,463)
Interest and miscellaneous income, net											606	851	1,315
INCOME BEFORE INCOME TAXES											367,076	306,362	232,803
Income tax expense											(88,391)	(30,357)	(15,217)
NET INCOME	75,609	80,560	69,079	53,437	56,230	[1]	104,909	[2]	56,454	58,412	278,685	276,005	217,586
OTHER COMPREHENSIVE INCOME (LOSS)
Foreign currency translation adjustment											4,352	3,546	4,162
New Zealand joint venture cash flow hedges											213	(2,373)	837
(Loss) gain from pension and postretirement plans, net of income tax (expense) benefit of ($339), $20,665, and $1,570											(496)	(46,263)	6,385
Total other comprehensive income (loss)											4,069	(45,090)	11,384
COMPREHENSIVE INCOME											$ 282,754	$ 230,915	$ 228,970
EARNINGS PER COMMON SHARE
Basic earnings per share	$ 0.61	$ 0.66	$ 0.56	$ 0.44	$ 0.46		$ 0.86		$ 0.46	$ 0.48	$ 2.27	$ 2.27	$ 1.81
Diluted earnings per share	$ 0.59	$ 0.62	$ 0.54	$ 0.42	$ 0.45		$ 0.84		$ 0.45	$ 0.47	$ 2.17	$ 2.20	$ 1.79
Dividends per share											$ 1.68	$ 1.52	$ 1.36

[1] Fourth quarter 2011 included a pre-tax expense of $6.5 million ($4.1 million after tax) due to an increase in a disposition reserve.

[2] Third quarter 2011 included a benefit of $16.0 million from the reversal of a reserve related to the taxability of the AFMC.