Summary of Significant Accounting Policies Earnings per share (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Loss Attributed to LP Common Shares [Abstract]
Income (loss) from continuing operations									$ 32.1	$ (172.1)	$ (32.6)
Loss from discontinued operations									(3.3)	(9.2)	(6.4)
Net income (loss) attributed to Louisiana-Pacific Corporation									$ 28.8	$ (181.3)	$ (39.0)
Denominator:
Basic - weighted average common shares outstanding									137.1	133.2	129.1
Dilutive effect of employee stock plans									2.3	0	0
Dilutive effect of stock warrants									3.2	0	0
Diluted shares outstanding									142.6	133.2	129.1
Basic earnings per share:
Income (loss) from continuing operations	$ 0.35	$ 0.23	$ (0.27)	$ (0.08)	$ (0.42)	$ (0.44)	$ (0.25)	$ (0.18)	$ 0.23	$ (1.29)	$ (0.25)
Loss from discontinued operations									$ (0.02)	$ (0.07)	$ (0.05)
Net income (loss) per share - basic	$ 0.33	$ 0.23	$ (0.27)	$ (0.08)	$ (0.42)	$ (0.49)	$ (0.27)	$ (0.18)	$ 0.21	$ (1.36)	$ (0.30)
Diluted earnings per share:
Income (loss) from continuing operations	$ 0.34	$ 0.22	$ (0.27)	$ (0.08)	$ (0.42)	$ (0.44)	$ (0.25)	$ (0.18)	$ 0.22	$ (1.29)	$ (0.25)
Loss from discontinued operations									$ (0.02)	$ (0.07)	$ (0.05)
Net income (loss) per share - diluted	$ 0.32	$ 0.22	$ (0.27)	$ (0.08)	$ (0.42)	$ (0.49)	$ (0.27)	$ (0.18)	$ 0.20	$ (1.36)	$ (0.30)
Antidilutive securities excluded from computation of earnings per share									5.3	7.1	9.1