Financial Instruments (Narrative) (Details) (USD $)	3 Months Ended		9 Months Ended		3 Months Ended		1 Months Ended	3 Months Ended		9 Months Ended		3 Months Ended	9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011 Eastern Spruce/Pine [Member] Commodity Swap Contract [Member] mbf	Oct. 13, 2010 Eastern Spruce/Pine [Member] Commodity Swap Contract [Member] mbf	Feb. 28, 2011 Southern Yellow Pine [Member] Commodity Swap Contract [Member] mbf	Sep. 30, 2011 Southern Yellow Pine [Member] Commodity Swap Contract [Member] mbf	Sep. 30, 2011 Other non-current assets [Member]	Sep. 30, 2011 Maximum [Member] Interest Rate Swap [Member]	Sep. 30, 2011 Interest Rate Swap [Member] Minimum [Member]	Sep. 30, 2011 Commodity Swap Contract [Member]	Sep. 30, 2011 Commodity Swap Contract [Member]
Derivatives, Fair Value [Line Items]
Number of interest rate swap agreements	8		8
Notional amounts	$ 63,250,000		$ 63,250,000
Debentures	22,500,000		22,500,000
Medium-term notes	40,750,000		40,750,000
Swaps fixed interest rate, minimum	6.95%		6.95%
Swaps fixed interest rate, maximum	8.89%		8.89%
LIBOR variable interest rate, minimum	4.738%		4.738%
LIBOR variable interest rate, maximum	7.805%		7.805%
Derivative, Maturity Date										Feb. 01, 2018	Jan. 01, 2012
Derivative asset									2,400,000
Derivative liability						33,000		31,200
Increase in carrying amount of debt	2,400,000		2,400,000
Net gain recognized in income	1,900,000	1,700,000	2,600,000	1,500,000
Decrease in carrying amount of debt	1,900,000	1,700,000	2,600,000	1,500,000
Unrealized gain or loss recognized in income	0		0
Net gain recognized resulting in reduction in interest expense	300,000	200,000	800,000	200,000
Hedge ineffectiveness recognized	0	0	0	0
Commodity contracts cash settlements each month (in mbf)					5,500			7,800
Cash settlements					300,000
Realized gain on settlement of commodity swap contract	300,000		600,000
Remaining commodity swap contract cash settled (in mbf)							7,150
Cash payment							200,000
Unrealized gains												$ 1,700,000	$ 4,400,000