Contingency Reserves Hardboard Contingencies Rollforward (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Loss Contingencies [Line Items]
Loss Contingency Accrual, Carrying Value, Period Increase (Decrease)	$ 0	$ (10.7)	$ 0	$ (10.7)
Loss Contingency Accrual [Roll Forward]
Beginning Balance, December 31			21.2
Ending Balance	20.1		20.1
Hardboard Siding Reserves [Member]
Loss Contingencies [Line Items]
Loss Contingency Accrual, Carrying Value, Period Increase (Decrease)		(10.7)	0
Loss Contingency Accrual [Roll Forward]
Beginning Balance, December 31			6.2	17.8
Payments made for claims			(0.3)	(0.4)
Payments made for administrative costs			(0.1)	(0.3)
Ending Balance	$ 5.8	$ 6.4	$ 5.8	$ 6.4