Goodwill and Other Intangible Assets (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Jun. 30, 2020	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Goodwill [Line Items]
Goodwill, Beginning Balance		$ 30	$ 16
Goodwill, Acquired During Period		0	14
Asset Impairment Charges		(5)
Goodwill		25	30	$ 16
Intangible Assets, Net (Excluding Goodwill)		61	51
Finite-lived Intangible Assets Acquired			15
Amortization of Intangible Assets		(5)	(5)	(4)
Intangible Assets, Net (Excluding Goodwill)		56	61	51
Finite-Lived Intangible Assets, Amortization Expense, Next Twelve Months		5
Licensing Agreements [Member]
Goodwill [Line Items]
Intangible Assets, Net (Excluding Goodwill)		38	41
Finite-lived Intangible Assets Acquired			0
Amortization of Intangible Assets		(4)	(3)
Intangible Assets, Net (Excluding Goodwill)		34	38	41
Licensing Agreements [Member] | CANADA
Goodwill [Line Items]
Intangible Assets, Net (Excluding Goodwill)		91
Technology-Based Intangible Assets [Member]
Goodwill [Line Items]
Intangible Assets, Net (Excluding Goodwill)		20	10
Finite-lived Intangible Assets Acquired			12
Amortization of Intangible Assets		(1)	(2)
Intangible Assets, Net (Excluding Goodwill)		19	20	10
Trademarks [Member]
Goodwill [Line Items]
Intangible Assets, Net (Excluding Goodwill)		3	0
Finite-lived Intangible Assets Acquired			3
Amortization of Intangible Assets		0	0
Intangible Assets, Net (Excluding Goodwill)		3	3	0
Siding
Goodwill [Line Items]
Goodwill, Beginning Balance		4	0
Goodwill, Acquired During Period	$ 4	0	4
Asset Impairment Charges		0
Goodwill		4	4	0
OSB
Goodwill [Line Items]
Goodwill, Beginning Balance		16	16
Goodwill, Acquired During Period		0	0
Asset Impairment Charges		0
Goodwill		16	16	16
Other
Goodwill [Line Items]
Goodwill, Beginning Balance		10	0
Goodwill, Acquired During Period		0	10
Asset Impairment Charges		(5)
Goodwill		5	$ 10	$ 0
Entreka [Member]
Goodwill [Line Items]
Asset Impairment Charges		$ (5)