Owens Corning (OC) 10-Q 28 Apr 21 2021 Q1 Quarterly report Financial data

DOCUMENT AND ENTITY INFORMATION

DOCUMENT AND ENTITY INFORMATION - shares	3 Months Ended
	Mar. 31, 2021	Apr. 23, 2021
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Mar. 31, 2021
Document Transition Report	false
Entity File Number	1-33100
Entity Registrant Name	Owens Corning
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	43-2109021
Entity Address, Address Line One	One Owens Corning Parkway,
Entity Address, City or Town	Toledo,
Entity Address, State or Province	OH
Entity Address, Postal Zip Code	43659
City Area Code	419
Local Phone Number	248-8000
Title of 12(b) Security	Common Stock, par value $0.01 per share
Trading Symbol	OC
Security Exchange Name	NYSE
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock Shares Outstanding		104,462,073
Entity Central Index Key	0001370946
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	Q1
Amendment Flag	false

CONSOLIDATED STATEMENTS OF EARN

CONSOLIDATED STATEMENTS OF EARNINGS (LOSS) - USD ($) shares in Thousands, $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Income Statement [Abstract]
NET SALES	$ 1,915	$ 1,601
COST OF SALES	1,471	1,295
Gross margin	444	306
OPERATING EXPENSES
Marketing and administrative expenses	174	179
Science and technology expenses	20	21
Goodwill impairment charge	0	944
Other (income) expenses, net	(48)	32
Total operating expenses	146	1,176
OPERATING INCOME (LOSS)	298	(870)
Non-operating income	(3)	(4)
EARNINGS (LOSS) BEFORE INTEREST AND TAXES	301	(866)
Interest expense, net	33	27
EARNINGS (LOSS) BEFORE TAXES	268	(893)
Income tax expense	59	24
Equity in net earnings of affiliates	1	1
NET EARNINGS (LOSS)	210	(916)
Net earnings attributable to noncontrolling interests	0	1
NET EARNINGS (LOSS) ATTRIBUTABLE TO OWENS CORNING	$ 210	$ (917)
EARNINGS (LOSS) PER COMMON SHARE ATTRIBUTABLE TO OWENS CORNING COMMON STOCKHOLDERS
Basic (in dollars per share)	$ 1.99	$ (8.43)
Diluted (in dollars per share)	$ 1.98	$ (8.43)
WEIGHTED AVERAGE COMMON SHARES
Basic (in shares)	105,400	108,800
Diluted (in shares)	106,000	108,800

CONSOLIDATED STATEMENTS OF COMP

CONSOLIDATED STATEMENTS OF COMPREHENSIVE EARNINGS (LOSS) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Statement of Comprehensive Income [Abstract]
NET EARNINGS (LOSS)	$ 210	$ (916)
Currency translation adjustment (net of tax of $(1) and $(10) for the three months ended March 31, 2021 and 2020, respectively)	(45)	(122)
Pension and other postretirement adjustment (net of tax of $0 for both the three months ended March 31, 2021 and 2020)	1	7
Hedging adjustment (net of tax of $(4) and $1 for the three months ended March 31, 2021 and 2020, respectively)	12	(1)
COMPREHENSIVE EARNINGS (LOSS)	178	(1,032)
Comprehensive earnings attributable to noncontrolling interests	0	1
COMPREHENSIVE EARNINGS (LOSS) ATTRIBUTABLE TO OWENS CORNING	$ 178	$ (1,033)

CONSOLIDATED STATEMENTS OF CO_2

CONSOLIDATED STATEMENTS OF COMPREHENSIVE EARNINGS (Parenthetical) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Statement of Comprehensive Income [Abstract]
Currency translation tax	$ (1)	$ (10)
Pension and other postretirement tax	0	0
Hedging tax	$ (4)	$ (1)

CONDENSED CONSOLIDATED BALANCE

CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($) $ in Millions		Mar. 31, 2021	Dec. 31, 2020
CURRENT ASSETS
Cash and cash equivalents		$ 605	$ 717
Receivables, less allowances of $10 at March 31, 2021 and $10 at December 31, 2020		1,167	919
Inventories		854	855
Other current assets		112	115
Total current assets		2,738	2,606
Property, plant and equipment, net		3,758	3,809
Operating lease right-of-use assets		145	154
Goodwill		980	989
Intangible assets		1,647	1,667
Deferred income taxes		28	28
Other non-current assets		264	228
TOTAL ASSETS		9,560	9,481
LIABILITIES AND EQUITY
Current operating lease liabilities		52	55
Other current liabilities		1,415	1,385
Total current liabilities		1,467	1,440
Long-term debt, net of current portion		3,145	3,126
Pension plan liability		153	159
Other employee benefits liability		169	171
Non-current operating lease liabilities		92	99
Deferred income taxes		341	332
Other liabilities		226	213
OWENS CORNING STOCKHOLDERS’ EQUITY
Preferred stock, par value $0.01 per share	[1]	0	0
Common stock, par value $0.01 per share	[2]	1	1
Additional paid in capital		4,056	4,059
Accumulated earnings		2,011	1,829
Accumulated other comprehensive deficit		(620)	(588)
Cost of common stock in treasury	[3]	(1,520)	(1,400)
Total Owens Corning stockholders’ equity		3,928	3,901
Noncontrolling interests		39	40
Total equity		3,967	3,941
TOTAL LIABILITIES AND EQUITY		$ 9,560	$ 9,481
[1]	10 shares authorized; none issued or outstanding at March 31, 2021 and December 31, 2020
[2]	400 shares authorized; 135.5 issued and 104.3 outstanding at March 31, 2021; 135.5 issued and 105.6 outstanding at December 31, 2020
[3]	shares at March 31, 2021 and 29.9 shares at December 31, 2020

CONSOLIDATED BALANCE SHEETS (Pa

CONSOLIDATED BALANCE SHEETS (Parentheticals) - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020
Statement of Financial Position [Abstract]
Allowance for doubtful accounts	$ 10	$ 11
Preferred stock, par value	$ 0.01	$ 0.01
Preferred stock, authorized	10,000,000	10,000,000
Preferred stock, issued	0	0
Preferred stock, outstanding	0	0
Common stock, par value	$ 0.01	$ 0.01
Common stock, authorized	400,000,000	400,000,000
Common stock, issued	135,500,000	135,500,000
Common stock, outstanding	108,600,000	109,000,000
Treasury stock shares	26,900,000	26,500,000

CONSOLIDATED STATEMENTS OF STOC

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	$ 1	$ (1,130)	$ 4,051	[1]	$ 2,319	$ (610)	[2]	$ 40	[3]
Beginning balance (in shares) at Dec. 31, 2019			109	26.5
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net earnings (loss) attributable to Owens Corning		(917)					(917)
Net earnings attributable to noncontrolling interests		1
Currency translation adjustment		(124)						(122)	[2]	(2)	[3]
Pension and other postretirement adjustment (net of tax)		7						7	[2]
Deferred loss on hedging transactions (net of tax)		(1)						(1)	[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		$ 16	(16)	[1]
Purchases of treasury stock (shares)			(1.6)	1.6
Purchases of treasury stock		(96)		$ (96)
Stock-based compensation expense		11			11	[1]
Dividends declared	[4]	(26)					(26)
Ending balance at Mar. 31, 2020		3,526	$ 1	$ (1,210)	4,046	[1]	1,376	(726)	[2]	39	[3]
Ending balance (in shares) at Mar. 31, 2020			107.8	27.7
Beginning balance at Dec. 31, 2020		3,941	$ 1	$ (1,400)	4,059		1,829	(588)		40
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					210			0
Net earnings attributable to noncontrolling interests		0
Currency translation adjustment		(46)						(45)		(1)
Pension and other postretirement adjustment (net of tax)		1						1
Deferred loss on hedging transactions (net of tax)		12						12
Issuance of common stock under share-based payment plans, shares			0.5	(0.5)
Issuance of common stock under share-based payment plans		7		$ 22	(15)
Purchases of treasury stock (shares)			(1.8)	(1.8)
Purchases of treasury stock		(142)		$ (142)
Stock-based compensation expense		12			12
Dividends declared	[4]	(28)					(28)
Ending balance at Mar. 31, 2021		$ 3,967	$ 1	$ (1,520)	$ 4,056		$ 2,011	$ (620)		$ 39
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.

CONSOLIDATED STATEMENTS OF ST_2

CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (Parenthetical) - $ / shares	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019
Statement of Stockholders' Equity [Abstract]
Dividends (dollars per share)	$ 0.24	$ 0.24	$ 0.24

CONSOLIDATED STATEMENTS OF CASH

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
NET CASH FLOW PROVIDED BY (USED FOR) OPERATING ACTIVITIES
NET EARNINGS (LOSS)	$ 210	$ (916)
Adjustments to reconcile net earnings (loss) to cash provided by (used for) operating activities:
Depreciation and amortization	119	116
Deferred income taxes	13	21
Provision for pension and other employee benefits liabilities	0	(1)
Stock-based compensation expense	12	11
Goodwill impairment charge	0	944
Intangible assets impairment charge	0	43
Other adjustments to reconcile net earnings (loss) to cash provided by (used for) operating activities	(6)	14
Changes in operating assets and liabilities	(136)	(265)
Pension fund contribution	(1)	(11)
Payments for other employee benefits liabilities	(4)	(4)
Other	(3)	(4)
Net cash flow provided by (used for) operating activities	204	(52)
NET CASH FLOW USED FOR INVESTING ACTIVITIES
Cash paid for property, plant, and equipment	(84)	(92)
Purchase of Interwrap	0	15
Derivative settlements	(35)	16
Other	(2)	0
Net cash flow used for investing activities	(121)	(61)
NET CASH FLOW (USED FOR) PROVIDED BY FINANCING ACTIVITIES
Proceeds from senior revolving credit and receivables securitization facilities	0	736
Payments on senior revolving credit and receivables securitization facilities	0	(336)
Net decrease in short-term debt	0	(11)
Dividends paid	(55)	(26)
Purchases of treasury stock	(142)	(96)
Other	3	(4)
Net cash flow (used for) provided by financing activities	(194)	213
Effect of exchange rate changes on cash	(1)	(38)
Net (decrease) increase in cash, cash equivalents, and restricted cash	(112)	62
Cash, cash equivalents and restricted cash at beginning of period	724	179
CASH, CASH EQUIVALENTS AND RESTRICTED CASH AT END OF PERIOD	612	241
Term Loan
NET CASH FLOW (USED FOR) PROVIDED BY FINANCING ACTIVITIES
Payments on senior revolving credit and receivables securitization facilities	$ 0	$ (50)

GENERAL

GENERAL	3 Months Ended
	Mar. 31, 2021
Accounting Changes and Error Corrections [Abstract]
GENERAL	GENERAL Unless the context requires otherwise, the terms “Owens Corning,” “Company,” “we” and “our” in this report refer to Owens Corning, a Delaware corporation, and its subsidiaries. The Consolidated Financial Statements included in this report are unaudited, pursuant to certain rules and regulations of the Securities and Exchange Commission, and include, in the opinion of the Company, normal recurring adjustments necessary for a fair statement of the results for the periods indicated, which, however, are not necessarily indicative of results which may be expected for the full year. The December 31, 2020 balance sheet data was derived from audited financial statements, but does not include all disclosures required by accounting principles generally accepted in the United States ("U.S."). In connection with the Consolidated Financial Statements and Notes included in this report, reference is made to the Consolidated Financial Statements and Notes contained in the Company’s Form 10-K for the year ended December 31, 2020 (the "2020 Form 10-K"). Certain reclassifications have been made to the periods presented for 2020 to conform to the classifications used in the periods presented for 2021. Revenue Recognition As of December 31, 2020, our contract liability balances (for extended warranties, down payments and deposits, collectively) totaled $66 million, of which $13 million was recognized as revenue in the first three months of 2021. As of March 31, 2021, our contract liability balances totaled $77 million. Cash, Cash Equivalents and Restricted Cash On the Consolidated Statements of Cash Flows, the total of Cash, cash equivalents and restricted cash includes restricted cash of $7 million as of March 31, 2021, December 31, 2020, March 31, 2020 and December 31, 2019. Restricted cash primarily represents amounts received from a counterparty related to its performance assurance on an executory contract, which is included in Other current assets on the Consolidated Balance Sheets. These amounts are contractually required to be set aside, and the counterparty can exchange the cash for another form of performance assurance at its discretion. Related Party Transactions In the first quarter of 2021, a related party relationship was established as a result of a member of the Company’s Board of Directors being named an executive officer of one of the Company’s preexisting suppliers. The related party transactions with this supplier consist of the purchase of raw materials. Purchases from the related party supplier for the three months ended March 31, 2021 were $20 million. As of March 31, 2021, amounts due to the related party supplier were $5 million. Leases During the first quarter of 2021, the Company entered into a lease for a warehouse located near our manufacturing facility in Fort Smith, Arkansas that is expected to commence in 2022. The lease is for a to-be-constructed warehouse where the Company will serve as the construction agent for the landlord. At no point during the construction period will the Company control the underlying asset as defined in ASC 842 (Leases). This lease will result in finance lease right-of-use assets and corresponding lease liabilities of approximately $35 million at the time of lease commencement. Accounting Pronouncements The following table summarizes recent ASU's issued by the Financial Accounting Standards Board (FASB) that could have an impact on the Company's Consolidated Financial Statements: Standard Description Effective Date for Company Effect on the Recently adopted standards: ASU 2019-12 "Income Taxes (Topic 740)" This standard simplifies accounting for income taxes including such topics as intraperiod tax allocations, franchise taxes and separate company financial statements. January 1, 2021 The adoption of this standard did not have a material effect on our consolidated financial statements.

SEGMENT INFORMATION

SEGMENT INFORMATION	3 Months Ended
	Mar. 31, 2021
Segment Reporting [Abstract]
SEGMENT INFORMATION	SEGMENT INFORMATION The Company has three reportable segments: Composites, Insulation and Roofing. Accounting policies for the segments are the same as those for the Company. The Company’s three reportable segments are defined as follows: Composites – The Company manufactures, fabricates and sells glass reinforcements in the form of fiber. Glass reinforcement materials are also used downstream by the Composites segment to manufacture and sell glass fiber products in the form of fabrics, non-wovens and other specialized products. Insulation – Within our Insulation segment, the Company manufactures and sells fiberglass insulation into residential, commercial, industrial and other markets for both thermal and acoustical applications. It also manufactures and sells glass fiber pipe insulation, flexible duct media, bonded and granulated mineral wool insulation, cellular glass insulation and foam insulation used in above- and below-grade construction applications. Roofing – Within our Roofing segment, the Company manufactures and sells residential roofing shingles, oxidized asphalt materials, roofing components used in residential and commercial construction and specialty applications, and synthetic packaging materials. NET SALES The following table summarizes our Net sales by segment and geographic region (in millions). Corporate eliminations (shown below) largely reflect intercompany sales from Composites to Roofing. External customer sales are attributed to geographic region based upon the location from which the product is sold to the external customer. For the three months ended March 31, 2021 Reportable Segments Composites Insulation Roofing Eliminations Consolidated Disaggregation Categories U.S. residential $ 75 $ 263 $ 659 $ (55) $ 942 U.S. commercial and industrial 146 162 22 — 330 Total United States 221 425 681 (55) 1,272 Europe 159 153 3 — 315 Asia-Pacific 138 36 3 — 177 Rest of world 41 86 24 — 151 NET SALES $ 559 $ 700 $ 711 $ (55) $ 1,915 For the three months ended March 31, 2020 Reportable Segments Composites Insulation Roofing Eliminations Consolidated Disaggregation Categories U.S. residential $ 66 $ 211 $ 492 $ (50) $ 719 U.S. commercial and industrial 151 162 28 — 341 Total United States 217 373 520 (50) 1,060 Europe 141 143 4 (1) 287 Asia-Pacific 105 20 3 — 128 Rest of world 31 67 28 — 126 NET SALES $ 494 $ 603 $ 555 $ (51) $ 1,601 EARNINGS BEFORE INTEREST AND TAXES Earnings before interest and taxes (EBIT) by segment consist of net sales less related costs and expenses and are presented on a basis that is used internally for evaluating segment performance. Certain items, such as general corporate expenses or income and certain other expense or income items, are excluded from the internal evaluation of segment performance. Accordingly, these items are not reflected in EBIT for our reportable segments and are included within Corporate, Other and Eliminations. The following table summarizes EBIT by segment (in millions): Three Months Ended 2021 2020 Reportable Segments Composites $ 79 $ 44 Insulation 82 39 Roofing 156 64 Total reportable segments 317 147 Restructuring costs (1) (5) Gains on sale of certain precious metals 20 10 Goodwill impairment charge — (944) Intangible assets impairment charge — (43) General corporate expense and other (35) (31) Total corporate, other and eliminations (16) (1,013) EBIT $ 301 $ (866)

INVENTORIES

INVENTORIES	3 Months Ended
	Mar. 31, 2021
Inventory Disclosure [Abstract]
INVENTORIES	INVENTORIES Inventories consist of the following (in millions): March 31, 2021 December 31, 2020 Finished goods $ 511 $ 532 Materials and supplies 343 323 Total inventories $ 854 $ 855

DERIVATIVE FINANCIAL INSTRUMENT

DERIVATIVE FINANCIAL INSTRUMENTS	3 Months Ended
	Mar. 31, 2021
Derivative Instruments and Hedging Activities Disclosure [Abstract]
DERIVATIVE FINANCIAL INSTRUMENTS	DERIVATIVE FINANCIAL INSTRUMENTS The Company is exposed to, among other risks, the impact of changes in commodity prices, foreign currency exchange rates, and interest rates in the normal course of business. The Company’s risk management program is designed to manage the exposure and volatility arising from these risks, and utilizes derivative financial instruments to offset a portion of these risks. The Company uses derivative financial instruments only to the extent necessary to hedge identified business risks, and does not enter into such transactions for trading purposes. The Company generally does not require collateral or other security with counterparties to these financial instruments and is therefore subject to credit risk in the event of nonperformance; however, the Company monitors credit risk and currently does not anticipate nonperformance by other parties. Contracts with counterparties generally contain right of offset provisions. These provisions effectively reduce the Company’s exposure to credit risk in situations where the Company has gain and loss positions outstanding with a single counterparty. It is the Company’s policy to offset on the Consolidated Balance Sheets the amounts recognized for derivative instruments with any cash collateral arising from derivative instruments executed with the same counterparty under a master netting agreement. As of March 31, 2021 and December 31, 2020, the Company did not have any amounts on deposit with any of its counterparties, nor did any of its counterparties have any amounts on deposit with the Company. Derivative Fair Values Our derivatives consist of natural gas forward swaps, cross-currency swaps, foreign exchange forward contracts and U.S. treasury rate lock agreements, all of which are over-the-counter and not traded through an exchange. The Company uses widely accepted valuation tools to determine fair value, such as discounting cash flows to calculate a present value for the derivatives. The models use Level 2 inputs, such as forward curves and other commonly quoted observable transactions and prices. The fair value of our derivatives and hedging instruments are all classified as Level 2 investments within the three-tier hierarchy. The following table presents the fair value of derivatives and hedging instruments and the respective location on the Consolidated Balance Sheets (in millions): Fair Value at Location March 31, 2021 December 31, 2020 Derivative assets designated as hedging instruments: Net investment hedges: Cross-currency swaps Other current assets $ 5 $ 5 Cash flow hedges: Natural gas forward swaps Other current assets $ 3 $ 2 Treasury interest rate lock Other non-current assets $ 19 $ 4 Derivative liabilities designated as hedging instruments: Net investment hedges: Cross-currency swaps Other liabilities $ 7 $ 11 Derivative assets not designated as hedging instruments: Foreign exchange forward contracts Other current assets $ 16 $ 2 Derivative liabilities not designated as hedging instruments: Foreign exchange forward contracts Other current liabilities $ 1 $ 45 Consolidated Statements of Earnings (Loss) Activity The following table presents the impact and respective location of derivative activities on the Consolidated Statements of Earnings (Loss) (in millions): Three Months Ended Location 2021 2020 Derivative activity designated as hedging instruments: Natural gas cash flow hedges: Amount of (gain)/loss reclassified from AOCI (as defined below) into earnings (a) Cost of sales $ (1) $ 2 Cross-currency swap net investment hedges: Amount of gain recognized in earnings on derivative amounts excluded from effectiveness testing Interest expense, net $ (1) $ (3) Derivative activity not designated as hedging instruments: Foreign currency: Amount of gain recognized in earnings (b) Other (income) expenses, net $ (20) $ (12) (a) Accumulated Other Comprehensive Earnings (Deficit) ("AOCI") (b) Gains related to foreign currency derivatives were substantially offset by net revaluation impacts on foreign currency denominated balance sheet exposures, which were also recorded in Other (income) expenses, net. Please refer to the "Other Derivatives" section below for additional detail. Consolidated Statements of Comprehensive Earnings (Loss) Activity The following table presents the impact of derivative activities on the Consolidated Statements of Comprehensive Earnings (Loss) (in millions): Amount of (Gain) Loss Recognized in Comprehensive Earnings (Loss) Three Months Ended Hedging Type Derivative Financial Instrument 2021 2020 Net investment hedge Cross-currency swaps $ (5) $ (42) Cash flow hedge Natural gas forward swaps $ (4) $ — Cash flow hedge Treasury interest rate lock $ (15) $ 1 Cash Flow Hedges The Company uses a combination of derivative financial instruments, which qualify as cash flow hedges, and physical contracts to manage forecasted exposure to electricity and natural gas prices. As of March 31, 2021, the notional amounts of these natural gas forward swaps was 2 million MMBtu (or MMBtu equivalent) based on European indices. In March 2020, the Company entered into a $175 million forward U.S. Treasury rate lock agreement to manage the U.S. Treasury portion of its interest rate risk associated with the anticipated issuance of certain 10-year fixed rate senior notes before the end of 2022. The Company intends to cash settle this agreement upon a future issuance of certain senior notes thereby effectively locking in the U.S. Treasury fixed interest rate in effect at the time the agreement was initiated. The locked fixed rate of this agreement is 0.994%. The Company has designated this outstanding forward U.S. Treasury rate lock agreement, which expires on December 15, 2022, as a cash flow hedge. Net Investment Hedges The Company has translation exposure resulting from translating the financial statements of foreign subsidiaries into U.S. Dollars, which is recognized in Currency translation adjustment (a component of AOCI). The Company uses cross-currency forward contracts to hedge portions of the net investment in foreign subsidiaries against fluctuations in foreign exchange rates. As of March 31, 2021, the notional amount of these derivative financial instruments was $218 million related to the U.S. Dollar and European Euro. In the second quarter of 2020, the Company unwound certain net investment hedge contracts, resulting in cash proceeds of $30 million. Other Derivatives The Company uses forward currency exchange contracts to manage existing exposures to foreign exchange risk related to assets and liabilities recorded on the Consolidated Balance Sheets. As of March 31, 2021, the Company had notional amounts of $606 million for non-designated derivative financial instruments related to foreign currency exposures in U.S. Dollars primarily related to Brazilian Real, Chinese Yuan, European Euro, Hong Kong Dollar, Indian Rupee, and South Korean Won. In addition, the Company had notional amounts of $105 million for non-designated derivative financial instruments related to foreign currency exposures in European Euro primarily related to the Polish Zloty and Russian Ruble.

GOODWILL AND OTHER INTANGIBLE A

GOODWILL AND OTHER INTANGIBLE ASSETS	3 Months Ended
	Mar. 31, 2021
Goodwill and Intangible Assets Disclosure [Abstract]
GOODWILL AND OTHER INTANGIBLE ASSETS	Goodwill The Company tests goodwill and indefinite-lived intangible assets for impairment during the fourth quarter of each year, or more frequently should circumstances change or events occur that would more likely than not reduce the fair value of a reporting unit below its carrying value. No testing was deemed necessary in the first three months of 2021. The changes in the net carrying value of goodwill by segment are as follows (in millions): Composites Insulation Roofing Total Balance at December 31, 2020 $ 57 $ 532 $ 400 $ 989 Additions 3 — — 3 Foreign Currency Translation (1) (9) (2) (12) Balance at March 31, 2021 $ 59 $ 523 $ 398 $ 980 During the first quarter of 2020, the Company’s significant share price reduction during the COVID-19 pandemic was determined to be an indicator of impairment under ASC 350. The COVID-19 pandemic was expected to have a negative impact on results for the remainder of 2020 and create uncertainty in our markets. The narrow cushion on the Insulation reporting unit and the high level of macroeconomic uncertainty caused the Company to perform an interim goodwill impairment test as of March 31, 2020 over the Insulation reporting unit. After evaluating and weighing all relevant events and circumstances, and considering the substantial excess fair values for the Roofing and Composites reporting units, we concluded that it was not more likely than not that the fair values of these reporting units were less than their carrying values. Consequently, we determined that it was not necessary to perform an interim impairment test for the Roofing and Composites reporting units. Based on the results of this interim testing over the Insulation reporting unit, the Company recorded a $944 million pre-tax non-cash impairment charge in the first quarter of 2020. This charge was recorded in Goodwill impairment charge on the Consolidated Statements of Earnings (Loss), and was included in the Corporate, Other and Eliminations reporting category. Other Intangible Assets The Company amortizes the cost of other intangible assets over their estimated useful lives which, individually, range up to 45 years. The Company's future cash flows are not materially impacted by its ability to extend or renew agreements related to its amortizable intangible assets. Other intangible assets consist of the following (in millions): March 31, 2021 December 31, 2020 Gross Carrying Amount Accumulated Amortization Net Carrying Amount Gross Accumulated Net Trademarks $ 1,103 $ — $ 1,103 $ 1,109 $ — $ 1,109 Customer relationships 559 (201) 358 570 (200) 370 Technology 324 (180) 144 327 (172) 155 Other (a) 46 (4) 42 36 (3) 33 Total other intangible assets $ 2,032 $ (385) $ 1,647 $ 2,042 $ (375) $ 1,667 (a) The Other category primarily includes emissions and quarry rights. In the first quarter of 2020, we performed an interim impairment test of certain indefinite-lived trademarks and trade names used by our Insulation segment, based on the macroeconomic conditions that precipitated the interim goodwill impairment test described above. Based on the results of this testing, the Company recorded pre-tax non-cash impairment charges totaling $43 million in the first quarter of 2020 related to two of the Insulation trademarks and trade names. These charges were recorded in Other (income) expenses, net on the Consolidated Statements of Earnings (Loss), and were included in the Corporate, Other and Eliminations reporting category. Non-cash impairment charges included a pre-tax impairment charge of $34 million for a trade name used by our European building and technical insulation business, and a pre-tax impairment charge of $9 million related to a trademark used on global cellular glass insulation products. There is one trade name used by our European building and technical insulation business within our Insulation segment that is at an increased risk of impairment. A change in the estimated long-term revenue growth rate or increase in the discount rate assumption could increase the likelihood of a future impairment for this asset. The affected asset had a carrying value of $166 million as of March 31, 2021. The estimated amortization expense for intangible assets for the next five years is as follows (in millions): Period Amortization 2022 $ 46 2023 $ 44 2024 $ 39 2025 $ 37 2026 $ 37

PROPERTY, PLANT AND EQUIPMENT

PROPERTY, PLANT AND EQUIPMENT	3 Months Ended
	Mar. 31, 2021
Property, Plant and Equipment [Abstract]
PROPERTY, PLANT AND EQUIPTMENT	PROPERTY, PLANT AND EQUIPMENT Property, plant and equipment consist of the following (in millions): March 31, December 31, 2020 Land $ 220 $ 222 Buildings and leasehold improvements 1,236 1,241 Machinery and equipment 5,160 5,155 Construction in progress 259 292 6,875 6,910 Accumulated depreciation (3,117) (3,101) Property, plant and equipment, net $ 3,758 $ 3,809 Machinery and equipment includes certain precious metals used in our production tooling, which comprise approximately 10% of total machinery and equipment as of both March 31, 2021 and December 31, 2020. Precious metals used in our production tooling are depleted as they are consumed during the production process, which typically represents an annual expense of about 3% of the outstanding carrying value.

WARRANTIES

WARRANTIES	3 Months Ended
	Mar. 31, 2021
Product Warranties Disclosures [Abstract]
WARRANTIES	WARRANTIES The Company records a liability for warranty obligations at the date the related products are sold. Adjustments are made as new information becomes available. Please refer to Note 1 of our 2020 Form 10-K for information about our separately-priced extended warranty contracts. A reconciliation of the warranty liability is as follows (in millions): Three Months Ended March 31, 2021 2020 Beginning balance $ 72 $ 64 Amounts accrued for current year 5 4 Settlements of warranty claims (3) (3) Ending balance $ 74 $ 65

RESTRUCTURING AND ACQUISITION-R

RESTRUCTURING AND ACQUISITION-RELATED COSTS	3 Months Ended
	Mar. 31, 2021
Restructuring and Related Activities [Abstract]
RESTRUCTURING AND ACQUISITION-RELATED COSTS	RESTRUCTURING AND ACQUISITION-RELATED COSTS The Company may incur restructuring, transaction and integration costs related to acquisitions, and may incur restructuring costs in connection with its global cost reduction and productivity initiatives. 2020 Insulation Restructuring Actions During the fourth quarter of 2020, the Company took actions to avoid future capital outlays and reduce costs in its global Insulation segment, mainly through decisions to close certain manufacturing facilities in Shanghai, China and Fresno, Texas, and optimize a facility in Parainen, Finland. During the first three months of 2021, the Company recorded $1 million of charges related to accelerated depreciation. The Company expects to recognize less than $5 million of incremental charges throughout 2021 related to these actions. 2020 Composites Restructuring Actions During 2020, the Company took actions to reduce costs throughout its global Composites segment primarily through global workforce reductions, closure of manufacturing lines and other asset write-offs. The Company does not expect to recognize significant incremental costs related to these actions. Acquisition-Related Restructuring Following the acquisitions of Paroc Group Oy ("Paroc") and Pittsburgh Corning Corporation and Pittsburgh Corning Europe NV (collectively, "Pittsburgh Corning") into the Company's Insulation segment, the Company took actions to realize expected synergies from the newly acquired operations. The Company does not expect to recognize significant incremental costs related to these actions. Consolidated Statements of Earnings (Loss) Classification The following table presents the impact and respective location of total restructuring costs on the Consolidated Statements of Earnings (Loss), which are included within Corporate, Other and Eliminations (in millions): Three Months Ended March 31, Type of cost Location 2021 2020 Accelerated depreciation Cost of sales $ 1 $ 1 Other exit costs Cost of sales — 2 Severance Other (income) expenses, net — 2 Total restructuring costs $ 1 $ 5 Summary of Unpaid Liabilities The following table summarizes the status of the unpaid liabilities from the Company's restructuring activities (in millions): 2020 Insulation Restructuring Actions 2020 Composites Restructuring Actions Acquisition-Related Restructuring Balance at December 31, 2020 $ 2 $ 2 $ 9 Restructuring costs 1 — — Payments (1) (1) (1) Accelerated depreciation and other non-cash items (1) — — Balance at March 31, 2021 $ 1 $ 1 $ 8 Cumulative charges incurred $ 24 $ 13 $ 29 As of March 31, 2021, the remaining liability balance is comprised of $10 million of severance, inclusive of $4 million of non-current severance and $6 million of severance the Company expects to pay over the next twelve months.

DEBT

DEBT	3 Months Ended
	Mar. 31, 2021
Debt Disclosure [Abstract]
DEBT	DEBT Details of the Company’s outstanding long-term debt, as well as the fair values, are as follows (in millions): March 31, 2021 December 31, 2020 Carrying Value Fair Value Carrying Value Fair Value 4.200% senior notes, net of discount and financing fees, due 2022 $ 184 105 % $ 184 106 % 4.200% senior notes, net of discount and financing fees, due 2024 396 111 % 396 111 % 3.400% senior notes, net of discount and financing fees, due 2026 397 108 % 397 111 % 3.950% senior notes, net of discount and financing fees, due 2029 445 110 % 445 115 % 3.875% senior notes, net of discount and financing fees, due 2030 297 109 % 297 115 % 7.000% senior notes, net of discount and financing fees, due 2036 368 136 % 368 142 % 4.300% senior notes, net of discount and financing fees, due 2047 588 109 % 588 120 % 4.400% senior notes, net of discount and financing fees, due 2048 390 110 % 390 121 % Various finance leases, due through 2036 (a) 101 100 % 78 100 % Other 2 n/a 2 n/a Total long-term debt 3,168 n/a 3,145 n/a Less – current portion (a) 23 100 % 19 100 % Long-term debt, net of current portion $ 3,145 n/a $ 3,126 n/a (a) The Company determined that the book value of the above noted long-term debt instruments approximates fair value. The fair values of the Company's outstanding long-term debt instruments were estimated using market observable inputs, including quoted prices in active markets, market indices and interest rate measurements. Within the hierarchy of fair value measurements, these are Level 2 fair values. Senior Notes The Company issued $300 million of 2030 senior notes on May 12, 2020. Interest on the notes is payable semiannually in arrears on June 1 and December 1 each year, beginning on December 1, 2020. The proceeds from these notes were used for general corporate purposes. The Company issued $450 million of 2029 senior notes on August 12, 2019. Interest on the notes is payable semiannually in arrears on February 15 and August 15 each year, beginning on February 15, 2020. The proceeds from these notes were used to repay $416 million of our 2022 senior notes and $34 million of our 2036 senior notes. The Company issued $400 million of 2048 senior notes on January 25, 2018. Interest on the notes is payable semiannually in arrears on January 30 and July 30 each year, beginning on July 30, 2018. The proceeds from these notes were used, along with borrowings on a $600 million term loan commitment and borrowings on the Receivables Securitization Facility (as defined below), to fund the purchase of Paroc in the first quarter of 2018. The Company issued $600 million of 2047 senior notes on June 26, 2017. Interest on the notes is payable semiannually in arrears on January 15 and July 15 each year, beginning on January 15, 2018. A portion of the proceeds from these notes was used to fund the purchase of Pittsburgh Corning in 2017 and for general corporate purposes. The remaining proceeds were used to repay $144 million of our 2019 senior notes and $140 million of our 2036 senior notes. The Company issued $400 million of 2026 senior notes on August 8, 2016. Interest on the notes is payable semiannually in arrears on February 15 and August 15 each year, beginning on February 15, 2017. A portion of the proceeds from these notes was used to repay $158 million of our 2016 senior notes. The remaining proceeds were used to pay down portions of our Receivables Securitization Facility and for general corporate purposes. The Company issued $400 million of 2024 senior notes on November 12, 2014. Interest on the notes is payable semiannually in arrears on June 1 and December 1 each year, beginning on June 1, 2015. A portion of the proceeds from these notes was used to repay $242 million of our 2016 senior notes and $105 million of our 2019 senior notes. The remaining proceeds were used to pay down our Senior Revolving Credit Facility (as defined below), finance general working capital needs, and for general corporate purposes. The Company issued $600 million of 2022 senior notes on October 17, 2012. Interest on the notes is payable semiannually in arrears on June 15 and December 15 each year, beginning on June 15, 2013. The proceeds of these notes were used to repay $250 million of our 2016 senior notes and $100 million of our 2019 senior notes and pay down our Senior Revolving Credit Facility. On October 31, 2006, the Company issued $550 million of 2036 senior notes. The proceeds of these notes were used to pay certain unsecured and administrative claims, finance general working capital needs and for general corporate purposes. Collectively, the senior notes above are referred to as the “Senior Notes.” The Senior Notes are general unsecured obligations of the Company and rank pari passu with all existing and future senior unsecured indebtedness of the Company. The Company has the option to redeem all or part of the Senior Notes at any time at a “make-whole” redemption price. The Company is subject to certain covenants in connection with the issuance of the Senior Notes that it believes are usual and customary. The Company was in compliance with these covenants as of March 31, 2021. Senior Revolving Credit Facility The Company has an $800 million senior revolving credit facility (the "Senior Revolving Credit Facility") with a maturity date in May 2024 that includes both borrowings and letters of credit. Borrowings under the Senior Revolving Credit Facility may be used for general corporate purposes and working capital. The Company has the discretion to borrow under multiple options, which provide for varying terms and interest rates including the United States prime rate, federal funds rate plus a spread or LIBOR plus a spread. The Senior Revolving Credit Facility contains various covenants, including a maximum allowed leverage ratio and a minimum required interest expense coverage ratio, that the Company believes are usual and customary for a senior unsecured credit agreement. The Company was in compliance with these covenants as of March 31, 2021. Please refer to the Credit Facility Utilization section below for liquidity information as of March 31, 2021. Receivables Securitization Facility The Company has a Receivables Purchase Agreement (RPA) that is accounted for as secured borrowings in accordance with ASC 860, "Accounting for Transfers and Servicing." Owens Corning Sales, LLC and Owens Corning Receivables LLC, each a subsidiary of the Company, have a $280 million RPA with certain financial institutions. The Company has the ability to borrow at the lenders' cost of funds, which approximates A-1/P-1 commercial paper rates vs. LIBOR, plus a fixed spread. In April 2021, the securitization facility (the "Receivables Securitization Facility") was amended to extend the maturity date to April 2024. The new agreement also includes fallback language related to a benchmark reference rate replacement, when a LIBOR transition occurs. The RPA contains various covenants, including a maximum allowed leverage ratio and a minimum required interest expense coverage ratio that the Company believes are usual and customary for a securitization facility. The Company was in compliance with these covenants as of March 31, 2021. Please refer to the Credit Facility Utilization section below for liquidity information as of March 31, 2021. Owens Corning Receivables LLC’s sole business consists of the purchase or acceptance through capital contributions of trade receivables and related rights from Owens Corning Sales, LLC and the subsequent retransfer of or granting of a security interest in such trade receivables and related rights to certain purchasers who are party to the RPA. Owens Corning Receivables LLC is a separate legal entity with its own separate creditors who will be entitled, upon its liquidation, to be satisfied out of Owens Corning Receivables LLC’s assets prior to any assets or value in Owens Corning Receivables LLC becoming available to Owens Corning Receivables LLC’s equity holders. The assets of Owens Corning Receivables LLC are not available to pay creditors of the Company or any other affiliates of the Company or Owens Corning Sales, LLC. Credit Facility Utilization The following table shows how the Company utilized its primary sources of liquidity (in millions): Balance at March 31, 2021 Senior Revolving Credit Facility Receivables Securitization Facility Facility size or borrowing limit $ 800 $ 280 Collateral capacity limitation on availability n/a — Outstanding borrowings — — Outstanding letters of credit 4 1 Availability on facility $ 796 $ 279 Short-Term Debt Short-term borrowings were $1 million at both March 31, 2021 and December 31, 2020. The short-term borrowings consisted of various operating lines of credit. The weighted average interest rate on all short-term borrowings was approximately 1.1% as of both March 31, 2021 and December 31, 2020.

PENSION PLANS AND OTHER POSTRET

PENSION PLANS AND OTHER POSTRETIREMENT BENEFITS	3 Months Ended
	Mar. 31, 2021
Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Abstract]
PENSION PLANS AND OTHER POSTRETIREMENT BENEFITS	Pension Plans The Company sponsors defined benefit pension plans. Under the plans, pension benefits are based on an employee’s years of service and, for certain categories of employees, qualifying compensation. Company contributions to these pension plans are determined by an independent actuary to meet or exceed minimum funding requirements. In our non-U.S. plans, the unrecognized cost of any retroactive amendments and actuarial gains and losses are amortized over the average future service period of plan participants expected to receive benefits. In our U.S. plans, the unrecognized cost of any retroactive amendments and actuarial gains and losses are amortized over the average remaining life expectancy of the inactive participants as substantially all of the plan participants are inactive. The following table provides information regarding pension expense recognized (in millions): Three Months Ended March 31, 2021 2020 U.S. Non-U.S. Total U.S. Non-U.S. Total Components of Net Periodic Pension Cost Service cost $ 1 $ 2 $ 3 $ 1 $ 1 $ 2 Interest cost 6 2 8 7 2 9 Expected return on plan assets (9) (5) (14) (11) (4) (15) Amortization of actuarial loss 3 1 4 3 1 4 Net periodic pension cost $ 1 $ — $ 1 $ — $ — $ — The Company does not expect to contribute to the U.S. pension plans during 2021. The Company expects to contribute $25 million in cash to non-U.S. plans during 2021. The Company made cash contributions of $1 million to the plans during the three months ended March 31, 2021. Postemployment and Postretirement Benefits Other than Pensions ("OPEB") The Company maintains healthcare and life insurance benefit plans for certain retired employees and their dependents. The health care plans in the United States are non-funded and pay either (1) stated percentages of covered medically necessary expenses, after subtracting payments by Medicare or other providers and after stated deductibles have been met, or (2) fixed amounts of medical expense reimbursement. The following table provides the components of net periodic benefit cost for aggregated U.S. and non-U.S. plans for the periods indicated (in millions): Three Months Ended 2021 2020 Components of Net Periodic Benefit Cost Service cost $ — $ — Interest cost 1 2 Amortization of prior service credit — (1) Amortization of actuarial gain (2) (2) Net periodic benefit income $ (1) $ (1)

CONTINGENT LIABILITIES AND OTHE

CONTINGENT LIABILITIES AND OTHER MATTERS	3 Months Ended
	Mar. 31, 2021
Commitments and Contingencies Disclosure [Abstract]
CONTINGENT LIABILITIES AND OTHER MATTERS	CONTINGENT LIABILITIES AND OTHER MATTERS The Company may be involved in various legal and regulatory proceedings relating to employment, antitrust, tax, product liability, environmental, contracts, intellectual property and other matters (collectively, “Proceedings”). The Company regularly reviews the status of such Proceedings along with legal counsel. Liabilities for such Proceedings are recorded when it is probable that the liability has been incurred and when the amount of the liability can be reasonably estimated. Liabilities are adjusted when additional information becomes available. Management believes that the amount of any reasonably possible losses in excess of any amounts accrued, if any, with respect to such Proceedings or any other known claim, including the matters described below under the caption Environmental Matters (the “Environmental Matters”), are not material to the Company’s financial statements. Management believes that the ultimate disposition of the Proceedings and the Environmental Matters will not have a material adverse effect on the Company’s financial condition. While the likelihood is remote, the disposition of the Proceedings and Environmental Matters could have a material impact on the results of operations, cash flows or liquidity in any given reporting period. Litigation and Regulatory Proceedings The Company is involved in litigation and regulatory proceedings from time to time in the regular course of its business. The Company believes that adequate provisions for resolution of all contingencies, claims and pending matters have been made for probable losses that are reasonably estimable. Environmental Matters The Company has established policies and procedures designed to ensure that its operations are conducted in compliance with all relevant laws and regulations and that enable the Company to meet its high standards for corporate sustainability and environmental stewardship. Our manufacturing facilities are subject to numerous foreign, federal, state and local laws and regulations relating to the presence of hazardous materials, pollution and protection of the environment, including emissions to air, reductions of greenhouse gases, discharges to water, management of hazardous materials, handling and disposal of solid wastes, use of chemicals in our manufacturing processes, and remediation of contaminated sites. All Company manufacturing facilities operate using an ISO 14001 or equivalent environmental management system. The Company’s 2030 Sustainability Goals include significant global reductions in energy use, water consumption, waste to landfill, and emissions of greenhouse gases, fine particulate matter, and volatile organic air emissions, and protection of biodiversity. Owens Corning is involved in remedial response activities and is responsible for environmental remediation at a number of sites, including certain of its currently owned or formerly owned plants. These responsibilities arise under a number of laws, including, but not limited to, the Federal Resource Conservation and Recovery Act, and similar state or local laws pertaining to the management and remediation of hazardous materials and petroleum. The Company has also been named a potentially responsible party under the U.S. Federal Superfund law, or state equivalents, at a number of disposal sites. The Company became involved in these sites as a result of government action or in connection with business acquisitions. As of March 31, 2021, the Company was involved with a total of 21 sites worldwide, including 8 Superfund and state equivalent sites and 13 owned or formerly owned sites. None of the liabilities for these sites are individually significant to the Company. Remediation activities generally involve a potential range of activities and costs related to soil, groundwater, and sediment contamination. This can include pre-cleanup activities such as fact-finding and investigation, risk assessment, feasibility studies, remedial action design and implementation (where actions may range from monitoring to removal of contaminants, to installation of longer-term remediation systems). A number of factors affect the cost of environmental remediation, including the number of parties involved in a particular site, the determination of the extent of contamination, the length of time the remediation may require, the complexity of environmental regulations, variability in clean-up standards, the need for legal action, and changes in remediation technology. Taking these factors into account, Owens Corning has predicted the costs of remediation reasonably estimated to be paid over a period of years. The Company accrues an amount on an undiscounted basis, consistent with the reasonable estimates of these costs when it is probable that a liability has been incurred. Actual cost may differ from these estimates for the reasons mentioned above. At March 31, 2021, the Company had an accrual totaling $5 million for these costs, of which the current portion is $1 million. Changes in required remediation procedures or timing of

STOCK COMPENSATION

STOCK COMPENSATION	3 Months Ended
	Mar. 31, 2021
Share-based Payment Arrangement [Abstract]
STOCK COMPENSATION	STOCK COMPENSATION Description of the Plan On April 18, 2019, the Company’s stockholders approved the Owens Corning 2019 Stock Plan (the “2019 Stock Plan”) which authorizes grants of stock options, stock appreciation rights, restricted stock awards, restricted stock units, bonus stock awards and performance share awards. At March 31, 2021, the number of shares remaining available under the 2019 Stock Plan for all stock awards was approximately 3.1 million. Prior to 2019, employees were eligible to receive stock awards under the Owens Corning 2016 Stock Plan and the Owens Corning 2013 Stock Plan. Total Stock-Based Compensation Expense Stock-based compensation expense included in Marketing and administrative expenses in the accompanying Consolidated Statements of Earnings (Loss) is as follows (in millions): Three Months Ended March 31, 2021 2020 Total stock-based compensation expense $ 12 $ 11 Stock Options The Company has granted stock options under its stockholder approved stock plans. The Company calculates a weighted-average grant-date fair value using a Black-Scholes valuation model for options granted. Compensation expense for options is measured based on the fair market value of the option on the date of grant, and is recognized on a straight-line basis over a four The Company has not granted stock options since the year ended December 31, 2014. As of March 31, 2021, there was no unrecognized compensation cost related to stock options and the range of exercise prices on outstanding stock options was $33.73 - $42.16. The following table summarizes the Company’s stock option activity: Weighted-Average Number of Options Exercise Price Remaining Intrinsic Value (in millions) Outstanding, December 31, 2020 361,775 $ 37.77 1.50 $ 14 Exercised (207,475) 37.36 Outstanding, March 31, 2021 154,300 $ 38.33 1.59 $ 8 Exercisable, March 31, 2021 154,300 $ 38.33 1.59 $ 8 Restricted Stock Awards and Restricted Stock Units The Company has granted restricted stock awards and restricted stock units (collectively referred to as “RSUs”) under its stockholder approved stock plans. Compensation expense for RSUs is measured based on the closing market price of the stock at date of grant and is recognized on a straight-line basis over the vesting period, which is typically three or four The following table summarizes the Company’s RSU plans: Number of RSUs Weighted-Average Balance at December 31, 2020 1,419,454 $ 54.99 Granted 307,133 81.35 Vested (302,237) 61.98 Forfeited (16,850) 64.24 Balance at March 31, 2021 1,407,500 $ 59.08 As of March 31, 2021, there was $49 million of total unrecognized compensation cost related to RSUs. That cost is expected to be recognized over a weighted-average period of 2.54 years. The total grant date fair value of shares vested during the three months ended March 31, 2021 and 2020 was $19 million and $19 million, respectively. Performance Share Awards and Performance Share Units The Company has granted performance share awards and performance share units (collectively referred to as “PSUs”) as a part of its long-term incentive plan. All outstanding performance grants will fully settle in stock. The amount of stock ultimately distributed from all performance shares is contingent on meeting internal company-based metrics or an external-based stock performance metric. In the three months ended March 31, 2021, the Company granted both internal company-based and external-based metric PSUs. Internal Company-based metrics The internal company-based metrics are based on various Company metrics and typically vest over a three-year period. The amount of stock distributed will vary from 0% to 300% of PSUs awarded depending on each award's design and performance versus the internal Company-based metrics. The initial fair value for all internal Company-based metric PSUs assumes that the performance goals will be achieved and is based on the grant date stock price. This assumption is monitored quarterly and if it becomes probable that such goals will not be achieved or will be exceeded, compensation expense recognized will be adjusted and previous surplus compensation expense recognized will be reversed or additional expense will be recognized. The expected term represents the period from the grant date to the end of the vesting period. Pro-rata vesting may be utilized in the case of death, disability or approved retirement and awards, if earned, will be paid at the end of the vesting period. External-based metrics The external-based metrics vest after a three The following table provides a summary of these assumptions for shares granted in 2021: Expected volatility 42.74% Risk free interest rate 0.18% Expected term (in years) 2.90 Grant date fair value of units granted $ 99.19 The risk-free interest rate was based on zero coupon United States Treasury bills at the grant date. The expected term represents the period from the grant date to the end of the three-year performance period. PSU Summary As of March 31, 2021, there was $27 million total unrecognized compensation cost related to PSUs. That cost is expected to be recognized over a weighted-average period of 2.21 years. There were no shares vested during the three months ended March 31, 2021. The total grant date fair value of shares vested during the three months ended March 31, 2020 was $1 million. The following table summarizes the Company’s PSU activity: Number Weighted-Average Balance at December 31, 2020 323,361 $ 69.20 Granted 148,968 85.07 Forfeited (8,132) 61.53 Balance at March 31, 2021 464,197 $ 69.26 Employee Stock Purchase Plan The Owens Corning Employee Stock Purchase Plan (ESPP) is a tax-qualified plan under Section 423 of the Internal Revenue Code. The purchase price of shares purchased under the ESPP is equal to 85% of the lower of the fair market value of shares of Owens Corning common stock at the beginning or ending of the offering period, which is a six-month period ending on May 31 and November 30 of each year. On April 16, 2020, the Company's stockholders approved the Amended and Restated Owens Corning Employee Stock Purchase Plan which increased the number of shares available for issuance under the plan by 4.2 million shares. As of March 31, 2021, 4.1 million shares remain available for purchase. Included in total stock-based compensation expense is $1 million of expense related to the Company's ESPP recognized during the three months ended March 31, 2021. During the three months ended March 31, 2020, the Company recognized expense of $1 million related to the Company's ESPP. As of March 31, 2021, there was $1 million of total unrecognized compensation cost related to the ESPP.

EARNINGS PER SHARE

EARNINGS PER SHARE	3 Months Ended
	Mar. 31, 2021
Earnings Per Share [Abstract]
EARNINGS PER SHARE	EARNINGS PER SHARE The following table is a reconciliation of weighted-average shares for calculating basic and diluted earnings (loss) per-share (in millions, except per share amounts): Three Months Ended 2021 2020 Net earnings (loss) attributable to Owens Corning $ 210 $ (917) Weighted-average number of shares outstanding used for basic earnings (loss) per share 105.4 108.8 Non-vested restricted and performance shares 0.5 — Options to purchase common stock 0.1 — Weighted-average number of shares outstanding and common equivalent shares used for diluted earnings (loss) per share 106.0 108.8 Earnings (loss) per common share attributable to Owens Corning common stockholders: Basic $ 1.99 $ (8.43) Diluted $ 1.98 $ (8.43) For the three months ended March 31, 2021, there were no non-vested restricted or performance shares that had an anti-dilutive effect on earnings per share. For the three months ended March 31, 2020, diluted earnings per share was equal to basic earnings per share due to the net loss attributable to Owens Corning. On December 3, 2020, the Board of Directors approved a share buy-back program under which the Company is authorized to repurchase up to 10 million shares of the Company’s outstanding common stock (the “Repurchase Authorization”). The Repurchase Authorization enables the Company to repurchase shares through the open market, privately negotiated, or other transactions. The actual number of shares repurchased will depend on timing, market conditions and other factors and is at the Company’s discretion. The Company repurchased 1.6 million shares of its common stock for $131 million during the three months ended March 31, 2021, under the Repurchase Authorization. As of March 31, 2021, 7.9 million shares remain available for repurchase under the Repurchase Authorization.

INCOME TAXES

INCOME TAXES	3 Months Ended
	Mar. 31, 2021
Income Tax Disclosure [Abstract]
INCOME TAXES	INCOME TAXES The following table provides the Income tax expense (in millions) and effective tax rate for the periods indicated: Three Months Ended March 31, 2021 2020 Income tax expense $ 59 $ 24 Effective tax rate 22 % -3 % The difference between the effective tax rate and the U.S. federal statutory tax rate of 21% for the three months ended March 31, 2021 is primarily due to U.S. state and local income tax expense, U.S. federal taxes on foreign earnings, adjustments to valuation allowances against certain deferred tax assets, excess tax benefits related to stock compensation, and other discrete adjustments. The difference between the effective tax rate and the U.S. federal statutory tax rate of 21% for the three months ended March 31, 2020 is primarily a result of charges related to the impairment of goodwill and certain other indefinite-lived intangible assets recorded in the three months ended March 31, 2020, which were mostly non-deductible. Non-cash charges of $18 million were recorded in the three months ended March 31, 2020 related to adjustments to valuation allowances against certain deferred tax assets. Additional items which account for the difference between the statutory rate of 21% and the effective rate are the impact of recording U.S. state and local income tax expense, the impact of U.S. federal taxes on foreign earnings, and other discrete adjustments. The Company continues to assert indefinite reinvestment in accordance with ASC 740 based on the laws as of enactment of the Tax Act.

CHANGES IN ACCUMULATED OTHER CO

CHANGES IN ACCUMULATED OTHER COMPREHENSIVE INCOME	3 Months Ended
	Mar. 31, 2021
Equity [Abstract]
CHANGES IN ACCUMULATED OTHER COMPREHENSIVE INCOME	CHANGES IN ACCUMULATED OTHER COMPREHENSIVE INCOME The following table summarizes the changes in accumulated other comprehensive income (deficit) (in millions): Three Months Ended 2021 2020 Currency Translation Adjustment Beginning balance $ (220) $ (282) Net investment hedge amounts classified into AOCI, net of tax 4 32 Loss on foreign currency translation (49) (154) Other comprehensive loss, net of tax (45) (122) Ending balance $ (265) $ (404) Pension and Other Postretirement Adjustment Beginning balance $ (372) $ (326) Amounts reclassified from AOCI to net earnings, net of tax (a) 2 7 Amounts classified into AOCI, net of tax (1) — Other comprehensive income, net of tax 1 7 Ending balance $ (371) $ (319) Hedging Adjustment Beginning balance $ 4 $ (2) Amounts reclassified from AOCI to net earnings, net of tax (b) (1) 2 Amounts classified into AOCI, net of tax 13 (3) Other comprehensive income/(loss), net of tax 12 (1) Ending balance $ 16 $ (3) Total AOCI ending balance $ (620) $ (726) (a) These AOCI components are included in the computation of total Pension and Other postretirement expense and are recorded in Non-operating income. See Note 10 for additional information. (b) Amounts reclassified from (loss)/gain on cash flow hedges are reclassified from AOCI to income when the hedged item affects earnings and is recognized in Cost of sales or Interest expense, net depending on the hedged item. See Note 4 for additional information.

SEGMENT INFORMATION (Tables)

SEGMENT INFORMATION (Tables)	3 Months Ended
	Mar. 31, 2021
Segment Reporting [Abstract]
Reconciliation of Revenue from Segments to Consolidated	The following table summarizes our Net sales by segment and geographic region (in millions). Corporate eliminations (shown below) largely reflect intercompany sales from Composites to Roofing. External customer sales are attributed to geographic region based upon the location from which the product is sold to the external customer. For the three months ended March 31, 2021 Reportable Segments Composites Insulation Roofing Eliminations Consolidated Disaggregation Categories U.S. residential $ 75 $ 263 $ 659 $ (55) $ 942 U.S. commercial and industrial 146 162 22 — 330 Total United States 221 425 681 (55) 1,272 Europe 159 153 3 — 315 Asia-Pacific 138 36 3 — 177 Rest of world 41 86 24 — 151 NET SALES $ 559 $ 700 $ 711 $ (55) $ 1,915 For the three months ended March 31, 2020 Reportable Segments Composites Insulation Roofing Eliminations Consolidated Disaggregation Categories U.S. residential $ 66 $ 211 $ 492 $ (50) $ 719 U.S. commercial and industrial 151 162 28 — 341 Total United States 217 373 520 (50) 1,060 Europe 141 143 4 (1) 287 Asia-Pacific 105 20 3 — 128 Rest of world 31 67 28 — 126 NET SALES $ 494 $ 603 $ 555 $ (51) $ 1,601
Schedule of Earnings before Interest and Taxes	The following table summarizes EBIT by segment (in millions): Three Months Ended 2021 2020 Reportable Segments Composites $ 79 $ 44 Insulation 82 39 Roofing 156 64 Total reportable segments 317 147 Restructuring costs (1) (5) Gains on sale of certain precious metals 20 10 Goodwill impairment charge — (944) Intangible assets impairment charge — (43) General corporate expense and other (35) (31) Total corporate, other and eliminations (16) (1,013) EBIT $ 301 $ (866)

INVENTORIES (Tables)

INVENTORIES (Tables)	3 Months Ended
	Mar. 31, 2021
Inventory Disclosure [Abstract]
Schedule of Inventory, Current	Inventories consist of the following (in millions): March 31, 2021 December 31, 2020 Finished goods $ 511 $ 532 Materials and supplies 343 323 Total inventories $ 854 $ 855

DERIVATIVE FINANCIAL INSTRUME_2

DERIVATIVE FINANCIAL INSTRUMENTS (Tables)	3 Months Ended
	Mar. 31, 2021
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Schedule of Derivative Assets and Liabilities at Fair Value	The following table presents the fair value of derivatives and hedging instruments and the respective location on the Consolidated Balance Sheets (in millions): Fair Value at Location March 31, 2021 December 31, 2020 Derivative assets designated as hedging instruments: Net investment hedges: Cross-currency swaps Other current assets $ 5 $ 5 Cash flow hedges: Natural gas forward swaps Other current assets $ 3 $ 2 Treasury interest rate lock Other non-current assets $ 19 $ 4 Derivative liabilities designated as hedging instruments: Net investment hedges: Cross-currency swaps Other liabilities $ 7 $ 11 Derivative assets not designated as hedging instruments: Foreign exchange forward contracts Other current assets $ 16 $ 2 Derivative liabilities not designated as hedging instruments: Foreign exchange forward contracts Other current liabilities $ 1 $ 45
Schedule of Fair Value Derivative Instruments Statements of Earnings Location	The following table presents the impact and respective location of derivative activities on the Consolidated Statements of Earnings (Loss) (in millions): Three Months Ended Location 2021 2020 Derivative activity designated as hedging instruments: Natural gas cash flow hedges: Amount of (gain)/loss reclassified from AOCI (as defined below) into earnings (a) Cost of sales $ (1) $ 2 Cross-currency swap net investment hedges: Amount of gain recognized in earnings on derivative amounts excluded from effectiveness testing Interest expense, net $ (1) $ (3) Derivative activity not designated as hedging instruments: Foreign currency: Amount of gain recognized in earnings (b) Other (income) expenses, net $ (20) $ (12) (a) Accumulated Other Comprehensive Earnings (Deficit) ("AOCI") (b) Gains related to foreign currency derivatives were substantially offset by net revaluation impacts on foreign currency denominated balance sheet exposures, which were also recorded in Other (income) expenses, net. Please refer to the "Other Derivatives" section below for additional detail. Consolidated Statements of Comprehensive Earnings (Loss) Activity The following table presents the impact of derivative activities on the Consolidated Statements of Comprehensive Earnings (Loss) (in millions): Amount of (Gain) Loss Recognized in Comprehensive Earnings (Loss) Three Months Ended Hedging Type Derivative Financial Instrument 2021 2020 Net investment hedge Cross-currency swaps $ (5) $ (42) Cash flow hedge Natural gas forward swaps $ (4) $ — Cash flow hedge Treasury interest rate lock $ (15) $ 1

GOODWILL AND OTHER INTANGIBLE_2

GOODWILL AND OTHER INTANGIBLE ASSETS (Tables)	3 Months Ended
	Mar. 31, 2021
Goodwill and Intangible Assets Disclosure [Abstract]
Schedule of Goodwill	Composites Insulation Roofing Total Balance at December 31, 2020 $ 57 $ 532 $ 400 $ 989 Additions 3 — — 3 Foreign Currency Translation (1) (9) (2) (12) Balance at March 31, 2021 $ 59 $ 523 $ 398 $ 980
Schedule of Finite-Lived Intangible Assets	Other intangible assets consist of the following (in millions): March 31, 2021 December 31, 2020 Gross Carrying Amount Accumulated Amortization Net Carrying Amount Gross Accumulated Net Trademarks $ 1,103 $ — $ 1,103 $ 1,109 $ — $ 1,109 Customer relationships 559 (201) 358 570 (200) 370 Technology 324 (180) 144 327 (172) 155 Other (a) 46 (4) 42 36 (3) 33 Total other intangible assets $ 2,032 $ (385) $ 1,647 $ 2,042 $ (375) $ 1,667
Finite-lived Intangible Assets Amortization Expense	The estimated amortization expense for intangible assets for the next five years is as follows (in millions): Period Amortization 2022 $ 46 2023 $ 44 2024 $ 39 2025 $ 37 2026 $ 37

PROPERTY, PLANT AND EQUIPMENT (

PROPERTY, PLANT AND EQUIPMENT (Tables)	3 Months Ended
	Mar. 31, 2021
Property, Plant and Equipment [Abstract]
Property, Plant and Equipment	Property, plant and equipment consist of the following (in millions): March 31, December 31, 2020 Land $ 220 $ 222 Buildings and leasehold improvements 1,236 1,241 Machinery and equipment 5,160 5,155 Construction in progress 259 292 6,875 6,910 Accumulated depreciation (3,117) (3,101) Property, plant and equipment, net $ 3,758 $ 3,809

WARRANTIES (Tables)

WARRANTIES (Tables)	3 Months Ended
	Mar. 31, 2021
Product Warranties Disclosures [Abstract]
Schedule of Product Warranty Liability	The Company records a liability for warranty obligations at the date the related products are sold. Adjustments are made as new information becomes available. Please refer to Note 1 of our 2020 Form 10-K for information about our separately-priced extended warranty contracts. A reconciliation of the warranty liability is as follows (in millions): Three Months Ended March 31, 2021 2020 Beginning balance $ 72 $ 64 Amounts accrued for current year 5 4 Settlements of warranty claims (3) (3) Ending balance $ 74 $ 65

RESTRUCTURING AND ACQUISITION_2

RESTRUCTURING AND ACQUISITION-RELATED COSTS (Tables)	3 Months Ended
	Mar. 31, 2021
Restructuring and Related Activities [Abstract]
Schedule of Restructuring Costs on the Consolidated Statements of Earnings	Consolidated Statements of Earnings (Loss) Classification The following table presents the impact and respective location of total restructuring costs on the Consolidated Statements of Earnings (Loss), which are included within Corporate, Other and Eliminations (in millions): Three Months Ended March 31, Type of cost Location 2021 2020 Accelerated depreciation Cost of sales $ 1 $ 1 Other exit costs Cost of sales — 2 Severance Other (income) expenses, net — 2 Total restructuring costs $ 1 $ 5
Schedule of Restructuring Reserve by Type of Cost	Summary of Unpaid Liabilities The following table summarizes the status of the unpaid liabilities from the Company's restructuring activities (in millions): 2020 Insulation Restructuring Actions 2020 Composites Restructuring Actions Acquisition-Related Restructuring Balance at December 31, 2020 $ 2 $ 2 $ 9 Restructuring costs 1 — — Payments (1) (1) (1) Accelerated depreciation and other non-cash items (1) — — Balance at March 31, 2021 $ 1 $ 1 $ 8 Cumulative charges incurred $ 24 $ 13 $ 29 As of March 31, 2021, the remaining liability balance is comprised of $10 million of severance, inclusive of $4 million of non-current severance and $6 million of severance the Company expects to pay over the next twelve months.

DEBT (Tables)

DEBT (Tables)	3 Months Ended
	Mar. 31, 2021
Debt Disclosure [Abstract]
Schedule of Long-term Debt Instruments	Details of the Company’s outstanding long-term debt, as well as the fair values, are as follows (in millions): March 31, 2021 December 31, 2020 Carrying Value Fair Value Carrying Value Fair Value 4.200% senior notes, net of discount and financing fees, due 2022 $ 184 105 % $ 184 106 % 4.200% senior notes, net of discount and financing fees, due 2024 396 111 % 396 111 % 3.400% senior notes, net of discount and financing fees, due 2026 397 108 % 397 111 % 3.950% senior notes, net of discount and financing fees, due 2029 445 110 % 445 115 % 3.875% senior notes, net of discount and financing fees, due 2030 297 109 % 297 115 % 7.000% senior notes, net of discount and financing fees, due 2036 368 136 % 368 142 % 4.300% senior notes, net of discount and financing fees, due 2047 588 109 % 588 120 % 4.400% senior notes, net of discount and financing fees, due 2048 390 110 % 390 121 % Various finance leases, due through 2036 (a) 101 100 % 78 100 % Other 2 n/a 2 n/a Total long-term debt 3,168 n/a 3,145 n/a Less – current portion (a) 23 100 % 19 100 % Long-term debt, net of current portion $ 3,145 n/a $ 3,126 n/a
Schedule of Line of Credit Facilities	The following table shows how the Company utilized its primary sources of liquidity (in millions): Balance at March 31, 2021 Senior Revolving Credit Facility Receivables Securitization Facility Facility size or borrowing limit $ 800 $ 280 Collateral capacity limitation on availability n/a — Outstanding borrowings — — Outstanding letters of credit 4 1 Availability on facility $ 796 $ 279

PENSION PLANS AND OTHER POSTR_2

PENSION PLANS AND OTHER POSTRETIREMENT BENEFITS (Tables)	3 Months Ended
	Mar. 31, 2021
Pension Plan
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Schedule of Net Benefit Costs	The following table provides information regarding pension expense recognized (in millions): Three Months Ended March 31, 2021 2020 U.S. Non-U.S. Total U.S. Non-U.S. Total Components of Net Periodic Pension Cost Service cost $ 1 $ 2 $ 3 $ 1 $ 1 $ 2 Interest cost 6 2 8 7 2 9 Expected return on plan assets (9) (5) (14) (11) (4) (15) Amortization of actuarial loss 3 1 4 3 1 4 Net periodic pension cost $ 1 $ — $ 1 $ — $ — $ —
Other Postretirement Benefits Plan
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Schedule of Net Benefit Costs	The following table provides the components of net periodic benefit cost for aggregated U.S. and non-U.S. plans for the periods indicated (in millions): Three Months Ended 2021 2020 Components of Net Periodic Benefit Cost Service cost $ — $ — Interest cost 1 2 Amortization of prior service credit — (1) Amortization of actuarial gain (2) (2) Net periodic benefit income $ (1) $ (1)

STOCK COMPENSATION (Tables)

STOCK COMPENSATION (Tables)	3 Months Ended
	Mar. 31, 2021
Share-based Payment Arrangement [Abstract]
Disclosure of Share-based Compensation Arrangements by Share-based Payment Award	Stock-based compensation expense included in Marketing and administrative expenses in the accompanying Consolidated Statements of Earnings (Loss) is as follows (in millions): Three Months Ended March 31, 2021 2020 Total stock-based compensation expense $ 12 $ 11
Schedule of Share-based Compensation, Stock Options, Activity	The following table summarizes the Company’s stock option activity: Weighted-Average Number of Options Exercise Price Remaining Intrinsic Value (in millions) Outstanding, December 31, 2020 361,775 $ 37.77 1.50 $ 14 Exercised (207,475) 37.36 Outstanding, March 31, 2021 154,300 $ 38.33 1.59 $ 8 Exercisable, March 31, 2021 154,300 $ 38.33 1.59 $ 8
Schedule of Share-based Compensation, Restricted Stock and Restricted Stock Units Activity	The following table summarizes the Company’s RSU plans: Number of RSUs Weighted-Average Balance at December 31, 2020 1,419,454 $ 54.99 Granted 307,133 81.35 Vested (302,237) 61.98 Forfeited (16,850) 64.24 Balance at March 31, 2021 1,407,500 $ 59.08
Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions	The following table provides a summary of these assumptions for shares granted in 2021: Expected volatility 42.74% Risk free interest rate 0.18% Expected term (in years) 2.90 Grant date fair value of units granted $ 99.19
Schedule of Share-based Compensation Arrangement by Share-based Payment Award, Performance-Based Units, Vested and Expected to Vest	The following table summarizes the Company’s PSU activity: Number Weighted-Average Balance at December 31, 2020 323,361 $ 69.20 Granted 148,968 85.07 Forfeited (8,132) 61.53 Balance at March 31, 2021 464,197 $ 69.26

EARNINGS PER SHARE (Tables)

EARNINGS PER SHARE (Tables)	3 Months Ended
	Mar. 31, 2021
Earnings Per Share [Abstract]
Schedule of Earnings Per Share, Basic and Diluted	The following table is a reconciliation of weighted-average shares for calculating basic and diluted earnings (loss) per-share (in millions, except per share amounts): Three Months Ended 2021 2020 Net earnings (loss) attributable to Owens Corning $ 210 $ (917) Weighted-average number of shares outstanding used for basic earnings (loss) per share 105.4 108.8 Non-vested restricted and performance shares 0.5 — Options to purchase common stock 0.1 — Weighted-average number of shares outstanding and common equivalent shares used for diluted earnings (loss) per share 106.0 108.8 Earnings (loss) per common share attributable to Owens Corning common stockholders: Basic $ 1.99 $ (8.43) Diluted $ 1.98 $ (8.43)

INCOME TAXES (Tables)

INCOME TAXES (Tables)	3 Months Ended
	Mar. 31, 2021
Income Tax Disclosure [Abstract]
Schedule of Effective Income Tax Rate Reconciliation	The following table provides the Income tax expense (in millions) and effective tax rate for the periods indicated: Three Months Ended March 31, 2021 2020 Income tax expense $ 59 $ 24 Effective tax rate 22 % -3 %

CHANGES IN ACCUMULATED OTHER _2

CHANGES IN ACCUMULATED OTHER COMPREHENSIVE INCOME (Tables)	3 Months Ended
	Mar. 31, 2021
Equity [Abstract]
Components of Accumulated Other Comprehensive Income (Loss)	The following table summarizes the changes in accumulated other comprehensive income (deficit) (in millions): Three Months Ended 2021 2020 Currency Translation Adjustment Beginning balance $ (220) $ (282) Net investment hedge amounts classified into AOCI, net of tax 4 32 Loss on foreign currency translation (49) (154) Other comprehensive loss, net of tax (45) (122) Ending balance $ (265) $ (404) Pension and Other Postretirement Adjustment Beginning balance $ (372) $ (326) Amounts reclassified from AOCI to net earnings, net of tax (a) 2 7 Amounts classified into AOCI, net of tax (1) — Other comprehensive income, net of tax 1 7 Ending balance $ (371) $ (319) Hedging Adjustment Beginning balance $ 4 $ (2) Amounts reclassified from AOCI to net earnings, net of tax (b) (1) 2 Amounts classified into AOCI, net of tax 13 (3) Other comprehensive income/(loss), net of tax 12 (1) Ending balance $ 16 $ (3) Total AOCI ending balance $ (620) $ (726) (a) These AOCI components are included in the computation of total Pension and Other postretirement expense and are recorded in Non-operating income. See Note 10 for additional information. (b) Amounts reclassified from (loss)/gain on cash flow hedges are reclassified from AOCI to income when the hedged item affects earnings and is recognized in Cost of sales or Interest expense, net depending on the hedged item. See Note 4 for additional information.

GENERAL (Details)

GENERAL (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020	Dec. 31, 2019
Accounting Changes and Error Corrections [Abstract]
Contract liability	$ 77		$ 66
Contract liability, revenue recognized	13
Restricted cash	7	$ 7	$ 7	$ 7
Goodwill impairment charge	0	$ 944
Related party transaction, expenses	20
Due to Related Parties	5
Lessee, operating lease, lease not yet commenced	$ 35

SEGMENT INFORMATION (Details)

SEGMENT INFORMATION (Details) $ in Millions	3 Months Ended
	Mar. 31, 2021USD ($)segment	Mar. 31, 2020USD ($)
Segment Reporting, Significant Reconciling Item [Line Items]
Number of reportable segments | segment	3
Disaggregated revenue	$ 1,915	$ 1,601
NET SALES	1,915	1,601
EBIT	301	(866)
Restructuring costs	(1)	(5)
Gains on sale of certain precious metals	20	10
Goodwill impairment charge	0	944
Intangible assets impairment charge	0	43
General corporate expense and other	(35)	(31)
Eliminations
Segment Reporting, Significant Reconciling Item [Line Items]
Disaggregated revenue	(55)	(51)
EBIT	(16)	(1,013)
U.S.
Segment Reporting, Significant Reconciling Item [Line Items]
Disaggregated revenue	1,272	1,060
U.S. | Eliminations
Segment Reporting, Significant Reconciling Item [Line Items]
Disaggregated revenue	(55)	(50)
U.S. | Residential
Segment Reporting, Significant Reconciling Item [Line Items]
Disaggregated revenue	942	719
U.S. | Residential | Eliminations
Segment Reporting, Significant Reconciling Item [Line Items]
Disaggregated revenue	(55)	(50)
U.S. | Commercial and Industrial Sector
Segment Reporting, Significant Reconciling Item [Line Items]
Disaggregated revenue	330	341
U.S. | Commercial and Industrial Sector | Eliminations
Segment Reporting, Significant Reconciling Item [Line Items]
Disaggregated revenue	0	0
Europe
Segment Reporting, Significant Reconciling Item [Line Items]
Disaggregated revenue	315	287
Europe | Eliminations
Segment Reporting, Significant Reconciling Item [Line Items]
Disaggregated revenue	0	(1)
Asia Pacific
Segment Reporting, Significant Reconciling Item [Line Items]
Disaggregated revenue	177	128
Asia Pacific | Eliminations
Segment Reporting, Significant Reconciling Item [Line Items]
Disaggregated revenue	0	0
Rest of world
Segment Reporting, Significant Reconciling Item [Line Items]
Disaggregated revenue	151	126
Rest of world | Eliminations
Segment Reporting, Significant Reconciling Item [Line Items]
Disaggregated revenue	0	0
Composites
Segment Reporting, Significant Reconciling Item [Line Items]
Disaggregated revenue	559	494
EBIT	79	44
Composites | U.S.
Segment Reporting, Significant Reconciling Item [Line Items]
Disaggregated revenue	221	217
Composites | U.S. | Residential
Segment Reporting, Significant Reconciling Item [Line Items]
Disaggregated revenue	75	66
Composites | U.S. | Commercial and Industrial Sector
Segment Reporting, Significant Reconciling Item [Line Items]
Disaggregated revenue	146	151
Composites | Europe
Segment Reporting, Significant Reconciling Item [Line Items]
Disaggregated revenue	159	141
Composites | Asia Pacific
Segment Reporting, Significant Reconciling Item [Line Items]
Disaggregated revenue	138	105
Composites | Rest of world
Segment Reporting, Significant Reconciling Item [Line Items]
Disaggregated revenue	41	31
Insulation
Segment Reporting, Significant Reconciling Item [Line Items]
Disaggregated revenue	700	603
EBIT	82	39
Insulation | U.S.
Segment Reporting, Significant Reconciling Item [Line Items]
Disaggregated revenue	425	373
Insulation | U.S. | Residential
Segment Reporting, Significant Reconciling Item [Line Items]
Disaggregated revenue	263	211
Insulation | U.S. | Commercial and Industrial Sector
Segment Reporting, Significant Reconciling Item [Line Items]
Disaggregated revenue	162	162
Insulation | Europe
Segment Reporting, Significant Reconciling Item [Line Items]
Disaggregated revenue	153	143
Insulation | Asia Pacific
Segment Reporting, Significant Reconciling Item [Line Items]
Disaggregated revenue	36	20
Insulation | Rest of world
Segment Reporting, Significant Reconciling Item [Line Items]
Disaggregated revenue	86	67
Roofing
Segment Reporting, Significant Reconciling Item [Line Items]
Disaggregated revenue	711	555
EBIT	156	64
Roofing | U.S.
Segment Reporting, Significant Reconciling Item [Line Items]
Disaggregated revenue	681	520
Roofing | U.S. | Residential
Segment Reporting, Significant Reconciling Item [Line Items]
Disaggregated revenue	659	492
Roofing | U.S. | Commercial and Industrial Sector
Segment Reporting, Significant Reconciling Item [Line Items]
Disaggregated revenue	22	28
Roofing | Europe
Segment Reporting, Significant Reconciling Item [Line Items]
Disaggregated revenue	3	4
Roofing | Asia Pacific
Segment Reporting, Significant Reconciling Item [Line Items]
Disaggregated revenue	3	3
Roofing | Rest of world
Segment Reporting, Significant Reconciling Item [Line Items]
Disaggregated revenue	24	28
Total Segments
Segment Reporting, Significant Reconciling Item [Line Items]
EBIT	$ 317	$ 147

INVENTORIES (Details)

INVENTORIES (Details) - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020
Inventory Disclosure [Abstract]
Finished goods	$ 511	$ 532
Materials and supplies	343	323
Total inventories	$ 854	$ 855

DERIVATIVE FINANCIAL INSTRUME_3

DERIVATIVE FINANCIAL INSTRUMENTS BALANCE SHEET (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020
Net Investment Hedging | Cross Currency Interest Rate Contract
Derivatives, Fair Value [Line Items]
Amount of (gain)/loss recognized in earnings	$ 5	$ 42
Nondesignated as Hedging Instrument | Foreign Exchange Contract | Other Expense [Member]
Derivatives, Fair Value [Line Items]
Amount of (gain)/loss recognized in earnings	(20)	$ (12)
Other current assets | Designated as Hedging Instrument | Net Investment Hedging | Cross Currency Interest Rate Contract
Derivatives, Fair Value [Line Items]
Derivative asset, fair value	5		$ 5
Other current assets | Designated as Hedging Instrument | Cash Flow Hedging | Cross Currency Interest Rate Contract
Derivatives, Fair Value [Line Items]
Derivative asset, fair value	3		2
Other current assets | Nondesignated as Hedging Instrument | Foreign Exchange Contract
Derivatives, Fair Value [Line Items]
Derivative asset, fair value	16		2
Other non-current assets | Designated as Hedging Instrument | Cash Flow Hedging | Cross Currency Interest Rate Contract
Derivatives, Fair Value [Line Items]
Derivative asset, fair value	19		4
Other liabilities | Designated as Hedging Instrument | Net Investment Hedging | Cross Currency Interest Rate Contract
Derivatives, Fair Value [Line Items]
Derivative liability, fair value	7		11
Current liabilities | Nondesignated as Hedging Instrument | Foreign Exchange Contract
Derivatives, Fair Value [Line Items]
Derivative liability, fair value	$ 1		$ 45

DERIVATIVE FINANCIAL INSTRUME_4

DERIVATIVE FINANCIAL INSTRUMENTS INCOME STATEMENT (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Cost of sales | Designated as Hedging Instrument | Energy Related Derivative
Derivative Instruments Gain Loss [Line Items]
Amount of (gain)/loss reclassified from AOCI (as defined below) into earnings (a)	$ 1	$ (2)
Interest expense, net | Designated as Hedging Instrument | Interest Rate Swap
Derivative Instruments Gain Loss [Line Items]
Derivative, Gain on Derivative	(1)	(3)
Other Expense | Nondesignated as Hedging Instrument | Foreign Exchange Contract
Derivative Instruments Gain Loss [Line Items]
Amount of (gain)/loss recognized in earnings	(20)	(12)
Net Investment Hedging | Cross Currency Interest Rate Contract
Derivative Instruments Gain Loss [Line Items]
Amount of (gain)/loss recognized in earnings	5	42
Cash Flow Hedging | Energy Related Derivative
Derivative Instruments Gain Loss [Line Items]
Amount of (gain)/loss recognized in earnings	4	0
Cash Flow Hedging | Treasury interest rate lock
Derivative Instruments Gain Loss [Line Items]
Amount of (gain)/loss recognized in earnings	$ 15	$ (1)

DERIVATIVE FINANCIAL INSTRUME_5

DERIVATIVE FINANCIAL INSTRUMENTS DERIVATIVE FINANCIAL INSTRUMENTS CASH FLOW (Details) MMBTU in Millions, $ in Millions	3 Months Ended
	Jun. 30, 2020USD ($)	Mar. 31, 2021USD ($)MMBTU
Derivative [Line Items]
Derivative, nonmonetary notional amount | MMBTU		2
Cross Currency Interest Rate Contract
Derivative [Line Items]
Proceeds from derivative instrument	$ 30
Treasury interest rate lock
Derivative [Line Items]
Derivative, notional amount		$ 175
Derivative, fixed interest rate		0.994%
United States of America, Dollars | Cross Currency Interest Rate Contract
Derivative [Line Items]
Derivative, notional amount		$ 218
Euro Member Countries, Euro | Foreign exchange forward contracts
Derivative [Line Items]
Derivative, notional amount		105
U.S. | Foreign exchange forward contracts
Derivative [Line Items]
Derivative, notional amount		$ 606

GOODWILL AND OTHER INTANGIBLE_3

GOODWILL AND OTHER INTANGIBLE ASSETS - Narrative (Details) $ in Millions	3 Months Ended
	Mar. 31, 2021USD ($)site
Finite-Lived Intangible Assets [Line Items]
Non-cash impairment charge	$ 944
Number of intangible assets impaired | site	2
Other
Finite-Lived Intangible Assets [Line Items]
Non-cash impairment charge	$ 43
Weighted average useful life	45 years
Insulation | Trade name
Finite-Lived Intangible Assets [Line Items]
Non-cash impairment charge	$ 34
Indefinite-lived intangible assets	166
Insulation | Trademarks
Finite-Lived Intangible Assets [Line Items]
Non-cash impairment charge	$ 9

GOODWILL AND OTHER INTANGIBLE_4

GOODWILL AND OTHER INTANGIBLE ASSETS - Goodwill Rollforward (Details) $ in Millions	3 Months Ended
	Mar. 31, 2021USD ($)
Goodwill [Line Items]
Balance at beginning of period	$ 989
Additions	3
Foreign Currency Translation	(12)
Balance at end of period	980
Composites
Goodwill [Line Items]
Balance at beginning of period	57
Additions	3
Foreign Currency Translation	(1)
Balance at end of period	59
Insulation
Goodwill [Line Items]
Balance at beginning of period	532
Additions	0
Foreign Currency Translation	(9)
Balance at end of period	523
Roofing
Goodwill [Line Items]
Balance at beginning of period	400
Additions	0
Foreign Currency Translation	(2)
Balance at end of period	$ 398

GOODWILL AND OTHER INTANGIBLE_5

GOODWILL AND OTHER INTANGIBLE ASSETS - Intangible Assets Rollforward (Details) - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount	$ 2,032	$ 2,042
Accumulated amortization	(385)	(375)
Net Carrying Amount	1,647	1,667
Trademarks
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount	1,103	1,109
Net Carrying Amount	1,103	1,109
Customer relationships
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount	559	570
Accumulated amortization	(201)	(200)
Net Carrying Amount	358	370
Technology
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount	324	327
Accumulated amortization	(180)	(172)
Net Carrying Amount	144	155
Other
Finite-Lived Intangible Assets [Line Items]
Gross carrying amount	46	36
Accumulated amortization	(4)	(3)
Net Carrying Amount	$ 42	$ 33

GOODWILL AND OTHER INTANGIBLE_6

GOODWILL AND OTHER INTANGIBLE ASSETS - Amortization Expense (Details) $ in Millions	Mar. 31, 2021USD ($)
Goodwill and Intangible Assets Disclosure [Abstract]
2022	$ 46
2023	44
2024	39
2025	37
2026	$ 37

PROPERTY, PLANT AND EQUIPMENT_2

PROPERTY, PLANT AND EQUIPMENT (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Dec. 31, 2020
Property Plant And Equipment [Line Items]
Property plant and equipment, gross	$ 6,875	$ 6,910
Accumulated depreciation	(3,117)	(3,101)
Property, plant and equipment, net	$ 3,758	$ 3,809
Precious metals depletion percentage	10.00%	10.00%
Precious metal percent of deprecation expense	0.03
Other significant noncash transaction, consideration received	20 million
Proceeds from sale of assets	$ 20
Land
Property Plant And Equipment [Line Items]
Property plant and equipment, gross	220	$ 222
Buildings and leasehold improvements
Property Plant And Equipment [Line Items]
Property plant and equipment, gross	1,236	1,241
Machinery and equipment
Property Plant And Equipment [Line Items]
Property plant and equipment, gross	5,160	5,155
Construction in progress
Property Plant And Equipment [Line Items]
Property plant and equipment, gross	$ 259	$ 292

WARRANTIES (Details)

WARRANTIES (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Movement In Standard And Extended Product Warranty Increase Decrease Roll Forward
Product warranty accrual, beginning balance	$ 72	$ 64
Amounts accrued for current year	5	4
Settlements of warranty claims	(3)	(3)
Product warranty accrual, ending balance	$ 74	$ 65

RESTRUCTURING AND ACQUISITION_3

RESTRUCTURING AND ACQUISITION-RELATED COSTS RESTRUCTURING (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020
Restructuring Cost and Reserve [Line Items]
Restructuring costs	$ 1	$ 5
Restructuring cost, expected cost	5
2020 Insulation Restructuring Actions
Restructuring Cost and Reserve [Line Items]
Restructuring costs	1
Restructuring reserve	1		$ 2
Payments	(1)
Accelerated depreciation and other non-cash items	1
Cumulative charges incurred	24
2020 Composites Restructuring Actions
Restructuring Cost and Reserve [Line Items]
Restructuring costs	0
Restructuring reserve	1		2
Payments	(1)
Accelerated depreciation and other non-cash items	0
Cumulative charges incurred	13
Pittsburgh Corning Related Restructuring
Restructuring Cost and Reserve [Line Items]
Restructuring costs	0
Restructuring reserve	8		$ 9
Payments	(1)
Accelerated depreciation and other non-cash items	0
Cumulative charges incurred	29
Accelerated depreciation
Restructuring Cost and Reserve [Line Items]
Restructuring costs	1
Accelerated depreciation | Cost of sales
Restructuring Cost and Reserve [Line Items]
Restructuring costs	1	1
Other exit costs | Cost of sales
Restructuring Cost and Reserve [Line Items]
Restructuring costs	0	2
Severance
Restructuring Cost and Reserve [Line Items]
Restructuring reserve	10
Restructuring reserve, noncurrent	4
Restructuring reserve, current	6
Severance | Other Expense
Restructuring Cost and Reserve [Line Items]
Restructuring costs	$ 0	$ 2

DEBT (Details)

DEBT (Details) - USD ($)	Aug. 12, 2019	Jun. 27, 2017	Mar. 31, 2021	Mar. 31, 2019	Jun. 30, 2016	Jun. 30, 2014	Dec. 31, 2020	Jun. 30, 2020	May 12, 2020	Apr. 01, 2018	Jan. 25, 2018	Jun. 30, 2017	Jun. 26, 2017	Aug. 08, 2016	Nov. 12, 2014	Oct. 17, 2012
Debt Instrument [Line Items]
Long-term debt			$ 3,168,000,000				$ 3,145,000,000
Fair value long-term debt			100.00%				100.00%
Other			$ 2,000,000				$ 2,000,000
Long-term debt, current maturities			23,000,000				19,000,000
Long-term debt, net of current portion			3,145,000,000				3,126,000,000
Line of credit facility, maximum borrowing capacity												$ 800,000,000
Short-term debt			$ 1,000,000				$ 1,000,000
Debt instrument, term			1 year
Short-term debt, weighted average interest rate, at point in time			1.10%				1.10%
Senior Notes Due 2022
Debt Instrument [Line Items]
Long-term debt			$ 184,000,000				$ 184,000,000
Fair value long-term debt			105.00%				106.00%
Long-term debt, percentage rate			4.20%					4.20%
Debt instrument, face amount																$ 600,000,000
Repayments of debt	$ 416,000,000
Senior Notes Due 2024
Debt Instrument [Line Items]
Long-term debt			$ 396,000,000				$ 396,000,000
Fair value long-term debt			111.00%				111.00%
Long-term debt, percentage rate			4.20%					4.20%
Debt instrument, face amount															$ 400,000,000
Senior Notes Due 2026
Debt Instrument [Line Items]
Long-term debt			$ 397,000,000				$ 397,000,000
Fair value long-term debt			108.00%				111.00%
Long-term debt, percentage rate			3.40%					3.40%
Debt instrument, face amount														$ 400,000,000
Senior Notes Due 2029
Debt Instrument [Line Items]
Long-term debt			$ 445,000,000				$ 445,000,000
Fair value long-term debt			110.00%				115.00%
Debt instrument, face amount	450,000,000
Senior Notes, Due 2030
Debt Instrument [Line Items]
Long-term debt			$ 297,000,000				$ 297,000,000
Fair value long-term debt			109.00%				115.00%
Debt instrument, face amount									$ 300,000,000
Senior Notes Due 2036
Debt Instrument [Line Items]
Long-term debt			$ 368,000,000				$ 368,000,000
Fair value long-term debt			136.00%				142.00%
Long-term debt, percentage rate			7.00%					7.00%
Debt instrument, face amount																$ 550,000,000
Repayments of debt	$ 34,000,000	$ 140,000,000
Senior Notes Due 2047
Debt Instrument [Line Items]
Long-term debt			$ 588,000,000				$ 588,000,000
Fair value long-term debt			109.00%				120.00%
Long-term debt, percentage rate			4.30%
Debt instrument, face amount													$ 600,000,000
Senior Notes Due 2048
Debt Instrument [Line Items]
Long-term debt			$ 390,000,000				$ 390,000,000
Fair value long-term debt			110.00%				121.00%
Long-term debt, percentage rate			4.40%
Debt instrument, face amount											$ 400,000,000
Various finance leases, due through 2032
Debt Instrument [Line Items]
Long-term debt			$ 101,000,000				$ 78,000,000
Fair value long-term debt			100.00%				100.00%
Senior Notes Due 2019
Debt Instrument [Line Items]
Repayments of debt		$ 144,000,000			$ 105,000,000	$ 100,000,000
Senior Notes Due 2016
Debt Instrument [Line Items]
Repayments of debt			$ 158,000,000		$ 242,000,000	$ 250,000,000
Senior Revolving Credit Facility B
Debt Instrument [Line Items]
Proceeds from issuance of debt				$ 600,000,000
Line of credit facility, maximum borrowing capacity			800,000,000
Availability on facility			796,000,000
Letter Of Credit Under Receivables Purchase Agreement
Debt Instrument [Line Items]
Long-term debt, current maturities										$ 280,000,000
Line of credit facility, maximum borrowing capacity			280,000,000
Availability on facility			$ 279,000,000

DEBT - Credit Facility Utilizat

DEBT - Credit Facility Utilization (Details) - USD ($) $ in Millions	Mar. 31, 2021	Jun. 30, 2017
Debt Instrument [Line Items]
Facility size or borrowing limit		$ 800
Senior Revolving Credit Facility B
Debt Instrument [Line Items]
Facility size or borrowing limit	$ 800
Outstanding borrowings	0
Outstanding letters of credit	4
Availability on facility	796
Letter Of Credit Under Receivables Purchase Agreement
Debt Instrument [Line Items]
Facility size or borrowing limit	280
Collateral capacity limitation on availability	0
Outstanding borrowings	0
Outstanding letters of credit	1
Availability on facility	$ 279

PENSION PLANS AND OTHER POSTR_3

PENSION PLANS AND OTHER POSTRETIREMENT BENEFITS (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2021
Defined Benefit Plan, Estimated Future Benefit Payments [Abstract]
Contributions by employer	$ 1
Pension Plan
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Service cost	3	$ 2
Interest cost	8	9
Expected return on plan assets	(14)	(15)
Amortization of actuarial loss	4	4
Net periodic benefit income	1	0
Other Postretirement Benefits Plan
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Service cost	0	0
Interest cost	1	2
Amortization of prior service credit	0	(1)
Amortization of actuarial loss	(2)	(2)
Net periodic benefit income	(1)	(1)
U.S. | Pension Plan
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Service cost	1	1
Interest cost	6	7
Expected return on plan assets	(9)	(11)
Amortization of actuarial loss	3	3
Net periodic benefit income	1	0
Foreign Plan | Pension Plan
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Service cost	2	1
Interest cost	2	2
Expected return on plan assets	(5)	(4)
Amortization of actuarial loss	1	1
Net periodic benefit income	$ 0	$ 0
Maximum | Scenario, Forecast | Foreign Plan
Defined Benefit Plan, Estimated Future Benefit Payments [Abstract]
Expected future employer contributions, current fiscal year			$ 25

CONTINGENT LIABILITIES AND OT_2

CONTINGENT LIABILITIES AND OTHER MATTERS (Details) $ in Millions	Mar. 31, 2021USD ($)site
Unusual or Infrequent Item, or Both [Line Items]
Environmental liability sites	21
Environmental exit costs, accrual | $	$ 5
Environmental exit costs, accrual, current | $	$ 1
Superfund Site
Unusual or Infrequent Item, or Both [Line Items]
Environmental liability sites	8
Owned or Formally Owned Sites
Unusual or Infrequent Item, or Both [Line Items]
Environmental liability sites	13

STOCK COMPENSATION - Narrative

STOCK COMPENSATION - Narrative (Details) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2021USD ($)$ / sharesshares	Mar. 31, 2020USD ($)	Apr. 16, 2020shares	Apr. 18, 2013
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Allocated share based compensation expense (less than)	$ 12	$ 11
Vesting period	4 years
Maximum employee subscription rate				85.00%
Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Exercise price range, exercisable options, weighted average exercise price | $ / shares	$ 25.45
Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Exercise price range, exercisable options, weighted average exercise price | $ / shares	$ 42.16
Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	4 years
Options Maximum term (in years)	10 years
Employee emergence equity program expense	$ 1
Options | Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Exercise price range, exercisable options, weighted average exercise price | $ / shares	$ 33.73
Options | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Exercise price range, exercisable options, weighted average exercise price | $ / shares	$ 42.16
Restricted Stock Awards and Restricted Stock Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	4 years
Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	2 years 6 months 14 days
Compensation cost not yet recognized	$ 49
Vested in period, fair value	$ 19	$ 19
Performance Stock Units (PSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	2 years 2 months 15 days
Compensation cost not yet recognized	$ 27
Vested in period, fair value	1
Employee Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation cost not yet recognized	$ 1
Stock Plan Member, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares available for grant | shares	3.1
Internal Based Performance Metric
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Performance stock payout minimum	0
Performance stock payout range maximum	3
External Based Performance Metric
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Vesting period	3 years
Performance stock payout minimum	0
Performance stock payout range maximum	2
Employee Stock Purchase Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of shares available for grant | shares	4.1		4.2

STOCK COMPENSATION - Stock Opti

STOCK COMPENSATION - Stock Option Activity (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Number of options, beginning balance	361,775
Exercised (in shares)	(207,475)
Number of options, ending balance	154,300
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Abstract]
Beginning Balance	$ 37.77
Exercised, weighted average exercise price	37.36
Ending Balance	$ 38.33
Weighted average remaining contractual term (in years)	1 year 7 months 2 days	1 year 6 months
Exercise price range, exercisable options, weighted average remaining contractual term (in years)	1 year 7 months 2 days
Intrinsic value	$ 8		$ 14
Intrinsic value, exercisable	$ 8

STOCK COMPENSATION - Restricted

STOCK COMPENSATION - Restricted Stock Activity (Details) - Restricted Stock Units (RSUs)	3 Months Ended
	Mar. 31, 2021$ / sharesshares
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Balance at December 31, 2020 | shares	1,419,454
Granted (in shares) | shares	307,133
Vested (in shares) | shares	(302,237)
Forfeited (in shares) | shares	(16,850)
Balance at March 31, 2021 | shares	1,407,500
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Balance at December 31, 2020 | $ / shares	$ 54.99
Granted, weighted average grant date fair value | $ / shares	81.35
Vested, weighted average grant date fair value | $ / shares	61.98
Forfeited, weighted average grant date fair value | $ / shares	64.24
Balance at March 31, 2021 | $ / shares	$ 59.08

STOCK COMPENSATION - Summary of

STOCK COMPENSATION - Summary of Assumptions (Details) - Performance Stock Units (PSUs) 2018	3 Months Ended
	Mar. 31, 2021$ / shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected volatility rate	42.74%
Risk free interest rate	0.18%
Expected term (in years)	2 years 10 months 24 days
Grant date fair value of units granted	$ 99.19

STOCK COMPENSATION - Performanc

STOCK COMPENSATION - Performance Stock Units (Details) - Performance Stock Units (PSUs)	3 Months Ended
	Mar. 31, 2021$ / sharesshares
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]
Balance at December 31, 2020 | shares	323,361
Granted (in shares) | shares	148,968
Forfeited (in shares) | shares	(8,132)
Balance at March 31, 2021 | shares	464,197
Share-based Compensation Arrangement by Share-based Payment Award, Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract]
Balance at December 31, 2020 | $ / shares	$ 69.20
Granted, weighted average grant date fair value | $ / shares	85.07
Forfeited, weighted average grant date fair value | $ / shares	61.53
Balance at March 31, 2021 | $ / shares	$ 69.26

EARNINGS PER SHARE (Details)

EARNINGS PER SHARE (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Oct. 24, 2016
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Net earnings (loss) attributable to Owens Corning	$ 210	$ (917)
Weighted-average number of shares outstanding used for basic earnings (loss) per share	105,400,000	108,800,000
Non-vested restricted and performance shares	500,000	0
Options to purchase common stock	100,000	0
Weighted-average number of shares outstanding and common equivalent shares used for diluted earnings (loss) per share	106,000,000	108,800,000
Basic (in dollars per share)	$ 1.99	$ (8.43)
Diluted (in dollars per share)	$ 1.98	$ (8.43)
Repurchase Program 2016
Equity Class Of Treasury Stock [Line Items]
Stock repurchase program, number of shares authorized to be repurchased			10,000,000
Stock repurchased during period, shares	1,600,000
Payments for repurchase of equity	$ 131

INCOME TAXES (Details)

INCOME TAXES (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Income Tax Disclosure [Abstract]
Income tax expense	$ 59	$ 24
Effective tax rate	22.00%	(3.00%)

CHANGES IN ACCUMULATED OTHER _3

CHANGES IN ACCUMULATED OTHER COMPREHENSIVE INCOME (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Total AOCI beginning balance	$ (588)
Amounts classified into AOCI, net of tax	0	$ 0
Amounts classified into AOCI, net of tax	12	(1)
Total AOCI ending balance	$ (620)	(726)
Short-term debt, weighted average interest rate, at point in time	1.10%		1.10%
Currency Translation Adjustment
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Total AOCI beginning balance	$ (220)	(282)
Net investment hedge amounts classified into AOCI, net of tax	4	32
Loss on foreign currency translation	(49)	(154)
Other comprehensive loss, net of tax	(45)	(122)
Total AOCI ending balance	(265)	(404)
Pension and Other Postretirement Adjustment
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Total AOCI beginning balance	(372)	(326)
Other comprehensive loss, net of tax	1	7
Amounts reclassified from AOCI to net earnings, net of tax	2	7
Amounts classified into AOCI, net of tax	(1)	0
Total AOCI ending balance	(371)	(319)
Hedging Adjustment
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Total AOCI beginning balance	4	(2)
Other comprehensive loss, net of tax	12	(1)
Amounts reclassified from AOCI to net earnings, net of tax	(1)	2
Amounts classified into AOCI, net of tax	13	(3)
Total AOCI ending balance	$ 16	$ (3)