CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) shares in Millions, $ in Millions		Total	Common Stock Outstanding	Treasury Stock	APIC		Accumulated Earnings	AOCI		NCI
Beginning balance at Dec. 31, 2019		$ 4,671.0	$ 1.0	$ (1,130.0)	$ 4,051.0	[1]	$ 2,319.0	$ (610.0)	[2]	$ 40.0	[3]
Beginning balance (in shares) at Dec. 31, 2019			109.0	26.5
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net earnings (loss) attributable to Owens Corning		(917.0)					(917.0)
Net earnings attributable to noncontrolling interests		1.0
Currency translation adjustment		(124.0)						(122.0)	[2]	(2.0)	[3]
Pension and other postretirement adjustment (net of tax)		7.0						7.0	[2]
Deferred loss on hedging transactions (net of tax)		(1.0)						(1.0)	[2]
Issuance of common stock under share-based payment plans, shares			0.4	(0.4)
Issuance of common stock under share-based payment plans		0.0		$ 16.0	(16.0)	[1]
Purchases of treasury stock (shares)			(1.6)	1.6
Purchases of treasury stock		(96.0)		$ (96.0)
Stock-based compensation expense		11.0			11.0	[1]
Dividends declared	[4]	(26.0)					(26.0)
Ending balance at Mar. 31, 2020		3,526.0	$ 1.0	$ (1,210.0)	4,046.0	[1]	1,376.0	(726.0)	[2]	39.0	[3]
Ending balance (in shares) at Mar. 31, 2020			107.8	27.7
Beginning balance at Dec. 31, 2020		3,941.0	$ 1.0	$ (1,400.0)	4,059.0		1,829.0	(588.0)		40.0
Beginning balance (in shares) at Dec. 31, 2020			105.6	29.9
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net earnings (loss) attributable to Owens Corning		210.0					210.0			0.0
Net earnings attributable to noncontrolling interests		0.0
Currency translation adjustment		(46.0)						(45.0)		(1.0)
Pension and other postretirement adjustment (net of tax)		1.0						1.0
Deferred loss on hedging transactions (net of tax)		12.0						12.0
Issuance of common stock under share-based payment plans, shares			0.5	(0.5)
Issuance of common stock under share-based payment plans		7.0		$ 22.0	(15.0)
Purchases of treasury stock (shares)			(1.8)	(1.8)
Purchases of treasury stock		(142.0)		$ (142.0)
Stock-based compensation expense		12.0			12.0
Dividends declared	[4]	(28.0)					(28.0)
Ending balance at Mar. 31, 2021		$ 3,967.0	$ 1.0	$ (1,520.0)	$ 4,056.0		$ 2,011.0	$ (620.0)		$ 39.0
Ending balance (in shares) at Mar. 31, 2021			104.3	31.2

[1] Additional Paid in Capital (APIC)

[2] Accumulated Other Comprehensive Earnings (Deficit) (“AOCI”)

[3] Noncontrolling Interest (“NCI”)

[4] Quarterly dividend declarations of $0.26 and $0.24 per share as of March 31, 2021 and March 31, 2020, respectively.