Income Taxes (Details) (USD $)	3 Months Ended			9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010	Mar. 31, 2010	Sep. 30, 2011	Sep. 30, 2010	Dec. 31, 2010
Income tax (provisions) expense	$ 3,223,000	$ 1,588,000		$ 7,505,000	$ 7,960,000
Deferred taxes, charge to earnings			3,000,000	7,506,000	8,801,000
Accrued as a receivable for interest, open tax refund	0			0		800,000
Maximum [Member]
Interest and penalties in tax provision, net benefit	100,000	100,000		100,000	100,000
Accrued for the payment of interest	100,000			100,000		100,000
Potlatch TRS [Member]
Income tax (provisions) expense	3,200,000	1,600,000		7,500,000	5,100,000
Income tax benefit related to continuing operations					300,000
REIT [Member]
Income tax (provisions) expense				$ 0	$ 400,000