Income Taxes (Details) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011	Dec. 31, 2011
Income tax (provisions) expense	$ 3,884,000	$ 3,223,000	$ 10,599,000	$ 7,505,000
Uncertain Tax Positions	0
Penalties and Interest Accrued	0		0		0
Potlatch TRS [Member]
Income tax (provisions) expense	3,900,000	3,200,000	10,500,000	7,500,000
REIT [Member]
Income tax (provisions) expense			$ 100,000