Contingency Reserves Hardboard Contingencies Rollforward (Details) (USD $) In Millions, unless otherwise specified			3 Months Ended
Mar. 31, 2012	Dec. 31, 2011	Mar. 31, 2012 Hardboard Siding Reserves [Member]	Mar. 31, 2011 Hardboard Siding Reserves [Member]	Sep. 30, 2010 Hardboard Siding Reserves [Member]	Dec. 31, 2009 Hardboard Siding Reserves [Member]
Loss Contingency Accrual [Roll Forward]
Beginning Balance	$ 20.7	$ 21.2	$ 6.2		$ 17.4	$ 17.8
Payments made for claims			(0.1)	(0.3)
Payments made for administrative costs			0	(0.1)
Ending Balance	$ 20.7	$ 21.2	$ 6.1		$ 17.4	$ 17.8

The carrying amount as of the balance sheet date of the combined total of loss contingency liabilities.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 5

-Paragraph 9, 10, 11, 12

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 450

-SubTopic 20

-Section 50

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6952336&loc=d3e14326-108349

Name:	us-gaap_LossContingencyAccrualAtCarryingValue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant