Segment Information Interim Financial Results (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
Segment Reporting Information [Line Items]
Product Warranty Accrual, Period Increase (Decrease)									$ 1.8	$ 0.4	$ 0
Net sales	458.7	467.8	427.8	361.5	312.2	350.6	362.4	331.7	1,715.8	1,356.9	1,383.6
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Extraordinary Items, Noncontrolling Interest	56.8	37.3	(45.5)	(10.6)	(49.6)	(74.2)	(33.9)	(26.4)	38.0	(184.1)	(47.9)
Income (loss) from continuing operations, including portion attributable to noncontrolling interest	49.1	31.4	(37.2)	(11.2)	(56.8)	(59.3)	(32.9)	(22.9)	32.1	(171.9)	(32.2)
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	46.1	31.3	(37.3)	(11.3)	(57.2)	(65.6)	(35.4)	(22.9)	28.8	(181.1)	(38.6)
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)
Income (loss) per share 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)
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)
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)
Operating income (loss)									107.4	(140.1)	(7.6)
Other Operating Income (Expense), Net	4.1	(1.2)	(0.2)	0.2	0	9.8	0.6	0.8	2.9	11.2	(0.1)
(Gain) loss on sale or impairment of long-lived assets	(0.4)	(4.3)	(0.1)	(0.1)	(0.9)	(65.0)	(2.5)	(5.5)	(4.9)	(73.9)	(2.4)
General corporate and other expenses, net	(22.4)	(18.1)	(18.2)	(20.1)	(16.9)	(15.2)	(16.5)	(17.8)	(78.7)	(66.4)	(73.4)
Nonoperating Income (Expense)	19.6	0.4	(54.8)	(0.1)	0.6	(4.0)	0.6	1.8	(69.4)	(44.0)	(40.3)
Foreign currency gains (losses)									(2.7)	(1.0)	2.2
Other-than-temporary investment impairment	0	0	0	0	(14.8)	0	0	0	0	(14.8)	(17.0)
Investment income	3.1	4.1	3.4	4.2	4.5	16.7	3.5	4.0	14.8	28.7	38.4
Interest Expense	(12.9)	(10.7)	(13.1)	(12.6)	(14.3)	(14.2)	(14.4)	(14.0)	(49.3)	(56.9)	(63.9)
Income (loss) from continuing operations before income taxes, extraordinary items, noncontrolling interest	61.1	39.3	(48.3)	(12.4)	(59.8)	(80.2)	(41.3)	(29.7)	39.7	(211.0)	(54.3)
Income Tax Expense (Benefit)	12.0	7.9	(11.1)	(1.2)	(3.0)	(20.9)	(8.4)	(6.8)	7.6	(39.1)	(22.1)
OSB [Member]
Segment Reporting Information [Line Items]
Net sales	243.1	226.6	194.9	149.0	130.6	138.8	140.6	132.1	814.1	542.0	602.7
Operating income (loss)	58.0	49.3	17.0	(0.3)	(15.5)	(16.0)	(22.9)	(9.1)	124.0	(63.5)	25.8
Siding [Member]
Segment Reporting Information [Line Items]
Net sales	116.7	134.1	137.0	113.1	93.0	112.0	118.6	106.2	500.9	429.8	427.8
Operating income (loss)	11.0	20.3	19.4	16.8	6.2	11.8	11.3	12.7	67.4	42.0	51.3
Engineered Wood Products [Member]
Segment Reporting Information [Line Items]
Net sales	51.6	61.5	51.7	48.6	46.4	54.9	53.6	48.3	213.4	203.3	192.0
Operating income (loss)	(4.6)	(3.0)	(3.4)	(2.8)	(3.6)	(3.2)	(3.2)	(5.5)	(13.9)	(15.5)	(21.3)
South America [Member]
Segment Reporting Information [Line Items]
Net sales	41.7	42.0	42.7	42.4	33.8	36.3	39.5	35.3	168.8	144.9	124.7
Operating income (loss)	6.8	4.5	3.6	3.1	1.5	2.3	4.2	3.6	18.0	11.6	7.2
Other
Segment Reporting Information [Line Items]
Net sales	7.5	9.1	10.7	10.0	9.1	9.5	10.4	10.5	37.4	39.4	42.9
Operating income (loss)	(1.2)	(2.0)	(1.9)	(0.7)	(6.6)	(3.2)	(2.0)	(0.7)	(5.7)	(12.5)	(1.1)
Intersegment sales
Segment Reporting Information [Line Items]
Net sales	(1.9)	(5.5)	(9.2)	(1.6)	(0.7)	(0.9)	(0.3)	(0.7)	(18.8)	(2.5)	(6.5)
OSB Siding [Member]
Segment Reporting Information [Line Items]
Product Warranty Accrual, Period Increase (Decrease)									$ (0.8)