Selected Segment Data (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Segment Reporting Information [Line Items]
Net sales:	$ 582.4	$ 493.0	$ 1,087.0	$ 964.7
Other operating charges and credits, net	(11.4)	0.0	(11.4)	(11.6)
Loss on sale or impairment of long-lived assets, net	0.7	0.5	0.7	0.6
Other Selling, General and Administrative Expense	27.2	22.0	51.2	44.7
Other non-operating items	1.4	0.4	1.9	(1.8)
Interest income	2.1	1.0	3.9	2.4
Interest expense, net of capitalized interest	(9.3)	(7.2)	(17.3)	(14.7)
Income (loss) from operations before taxes	47.9	(18.5)	62.6	(59.3)
Provision (benefit) for income taxes	16.2	1.0	20.6	(5.3)
Net income (loss)	31.7	(19.5)	42.0	(54.0)
Operating profit (loss):	52.2	(14.1)	71.1	(47.3)
OSB [Member]
Segment Reporting Information [Line Items]
Net sales:	252.8	211.0	469.8	401.2
Operating profit (loss):	44.0	(18.1)	59.3	(46.5)
Siding [Member]
Segment Reporting Information [Line Items]
Net sales:	207.2	163.9	388.5	337.4
Operating profit (loss):	41.8	29.2	68.7	62.1
Engineered Wood Products [Member]
Segment Reporting Information [Line Items]
Net sales:	78.0	72.0	149.8	136.8
Operating profit (loss):	0.5	(2.3)	(2.0)	(6.4)
South America [Member]
Segment Reporting Information [Line Items]
Net sales:	41.0	38.7	71.5	74.6
Operating profit (loss):	6.9	2.0	12.0	4.4
Other [Member]
Segment Reporting Information [Line Items]
Net sales:	6.6	7.4	12.7	14.7
Operating profit (loss):	(0.2)	(1.0)	(0.6)	(1.9)
Intersegment elimination [Member]
Segment Reporting Information [Line Items]
Net sales:	$ (3.2)	$ 0.0	$ (5.3)	$ 0.0