Condensed Consolidated Statements of Income and Comprehensive Income (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011	Dec. 31, 2011
SALES	$ 408,988	$ 385,091	$ 1,136,694	$ 1,100,218
Costs and Expenses
Cost of sales	278,651	266,184	794,519	786,467
Selling and general expenses	15,837	15,762	51,705	48,187
Other operating expense (income), net (Note 15)	1,392	(4,171)	(5,054)	(5,580)
Costs and Expenses, Total	295,880	277,775	841,170	829,074
Equity in income of New Zealand joint venture	66	994	250	3,817
OPERATING INCOME	113,174	108,310	295,774	274,961
Interest expense	(8,253)	(12,356)	(36,133)	(38,300)
Interest and miscellaneous income, net	234	331	294	935
INCOME BEFORE INCOME TAXES	105,155	96,285	259,935	237,596
Income tax (expense) benefit	(24,595)	8,624	(56,859)	(17,822)
NET INCOME	80,560	104,909	203,076	219,774	276,005
OTHER COMPREHENSIVE INCOME (LOSS)
Foreign currency translation adjustment	5,373	3,584	3,115	11,314	3,546
New Zealand joint venture cash flow hedges	878	(630)	86	(498)	(2,373)
Amortization of losses from pension and postretirement plans, net of income tax expense of $1,482, $1,017, $4,332 and $2,871	3,401	2,261	9,943	6,449	(46,263)
Total other comprehensive income	9,652	5,215	13,144	17,265
COMPREHENSIVE INCOME	$ 90,212	$ 110,124	$ 216,220	$ 237,039
EARNINGS PER COMMON SHARE (Note 2)
Basic earnings per share	$ 0.66	$ 0.86	$ 1.66	$ 1.81
Diluted earnings per share	$ 0.62	$ 0.84	$ 1.58	$ 1.75
Dividends per share	$ 0.44	$ 0.40	$ 1.24	$ 1.12	$ 1.52