Core Natural Resources 10-Q 10 Nov 20 2020 Q3 Quarterly report Financial data

Cover

Cover - shares	9 Months Ended
	Oct. 03, 2020	Nov. 03, 2020
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Oct. 3, 2020
Document Transition Report	false
Entity File Number	1-14315
Entity Registrant Name	Cornerstone Building Brands, Inc.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	76-0127701
Entity Address, Address Line One	5020 Weston Parkway
Entity Address, Address Line Two	Suite 400
Entity Address, City or Town	Cary
Entity Address, State or Province	NC
Entity Address, Postal Zip Code	27513
City Area Code	866
Local Phone Number	419-0042
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Title of 12(b) Security	Common Stock $0.01 par value per share
Trading Symbol	CNR
Security Exchange Name	NYSE
Entity Common Stock, Shares Outstanding		125,101,514
Entity Central Index Key	0000883902
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	Q3
Amendment Flag	false

CONSOLIDATED STATEMENTS OF OPER

CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Oct. 03, 2020	Sep. 28, 2019	Oct. 03, 2020	Sep. 28, 2019
Income Statement [Abstract]
Sales	$ 1,227,253	$ 1,285,043	$ 3,426,000	$ 3,645,332
Cost of sales	929,751	975,240	2,642,880	2,844,949
Gross profit	297,502	309,803	783,120	800,383
Selling, general and administrative expenses	137,250	154,034	436,575	466,368
Intangible asset amortization	45,446	44,725	135,547	132,699
Restructuring and impairment charges, net	2,918	4,984	32,164	15,522
Strategic development and acquisition related costs	7,909	10,500	13,550	36,668
Goodwill impairment	0	0	503,171	0
Income (loss) from operations	103,979	95,560	(337,887)	149,126
Interest income	328	155	1,007	491
Interest expense	(51,519)	(56,549)	(158,738)	(173,134)
Foreign exchange gain (loss)	812	(616)	(1,300)	1,084
Other income (expense), net	(23)	717	(25)	665
Income (loss) before income taxes	53,577	39,267	(496,943)	(21,768)
Provision (benefit) for income taxes	23,061	14,103	(12,285)	(4,448)
Net income (loss)	30,516	25,164	(484,658)	(17,320)
Net income allocated to participating securities	(488)	(374)	0	0
Net income (loss) applicable to common shares	$ 30,028	$ 24,790	$ (484,658)	$ (17,320)
Income (loss) per common share:
Basic (in USD per share)	$ 0.24	$ 0.20	$ (3.86)	$ (0.14)
Diluted (in USD per share)	$ 0.24	$ 0.20	$ (3.86)	$ (0.14)
Weighted average number of common shares outstanding:
Basic (in shares)	125,100	125,557	125,655	125,526
Diluted (in shares)	125,289	125,558	125,655	125,526

CONSOLIDATED STATEMENTS OF COMP

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Oct. 03, 2020	Sep. 28, 2019	Oct. 03, 2020	Sep. 28, 2019
Comprehensive income (loss):
Net income (loss)	$ 30,516	$ 25,164	$ (484,658)	$ (17,320)
Other comprehensive income (loss), net of tax:
Foreign exchange translation gains (losses)	7,354	(1,862)	6,357	4,278
Unrealized gain (loss) on derivative instruments, net of income tax of $(426), $2,054, $12,788 and $9,267, respectively	194	(6,858)	(41,711)	(29,604)
Other comprehensive income (loss)	7,548	(8,720)	(35,354)	(25,326)
Comprehensive income (loss)	$ 38,064	$ 16,444	$ (520,012)	$ (42,646)

CONSOLIDATED STATEMENTS OF CO_2

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) (Parenthetical) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Oct. 03, 2020	Sep. 28, 2019	Oct. 03, 2020	Sep. 28, 2019
Statement of Comprehensive Income [Abstract]
Unrealized loss on derivative instruments, tax (benefit) expense	$ (426)	$ 2,054	$ 12,788	$ 9,267

CONSOLIDATED BALANCE SHEETS

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Oct. 03, 2020	Dec. 31, 2019
Current assets:
Cash and cash equivalents	$ 627,603	$ 98,386
Restricted cash	6,223	3,921
Accounts receivable, less allowances of $13,411 and $9,962, respectively	578,684	491,740
Inventories, net	408,897	439,194
Income taxes receivable	34,310	48,466
Investments in debt and equity securities, at market	1,917	3,776
Prepaid expenses and other	73,096	78,516
Assets held for sale	5,087	1,750
Total current assets	1,735,817	1,165,749
Property, plant and equipment, less accumulated depreciation of $619,650 and $556,143, respectively	635,904	652,841
Lease right-of-use assets	277,037	316,155
Goodwill	1,189,992	1,669,594
Intangible assets, net	1,623,133	1,740,700
Deferred income taxes	1,139	7,510
Other assets, net	11,959	11,797
Total assets	5,474,981	5,564,346
Current liabilities:
Current portion of long-term debt	25,600	25,600
Accounts payable	229,353	205,629
Accrued compensation and benefits	78,269	92,130
Accrued interest	32,001	19,070
Accrued income taxes	2,730	0
Current portion of lease liabilities	69,408	72,428
Other accrued expenses	258,890	233,687
Total current liabilities	696,251	648,544
Long-term debt	3,567,302	3,156,924
Deferred income taxes	244,468	291,987
Long-term lease liabilities	210,446	243,780
Other long-term liabilities	336,224	287,793
Total long-term liabilities	4,358,440	3,980,484
Stockholders’ equity:
Common stock, $0.01 par value; 200,000,000 authorized; 125,128,804 and 125,101,519 shares issued and outstanding at October 3, 2020, respectively; and 126,110,000 and 126,054,487 shares issued and outstanding at December 31, 2019, respectively	1,252	1,261
Additional paid-in capital	1,253,877	1,248,787
Accumulated deficit	(766,565)	(281,229)
Accumulated other comprehensive loss, net	(67,752)	(32,398)
Treasury stock, at cost (27,285 and 55,513 shares at October 3, 2020 and December 31, 2019, respectively)	(522)	(1,103)
Total stockholders’ equity	420,290	935,318
Total liabilities and stockholders’ equity	$ 5,474,981	$ 5,564,346

CONSOLIDATED BALANCE SHEETS (Pa

CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	Oct. 03, 2020	Dec. 31, 2019
Statement of Financial Position [Abstract]
Allowance for doubtful accounts receivable	$ 13,411	$ 9,962
Accumulated depreciation on property, plant and equipment	$ 619,650	$ 556,143
Common stock, par value (in USD per share)	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	200,000,000	200,000,000
Common stock shares issued (in shares)	125,128,804	126,110,000
Common stock, shares outstanding (in shares)	125,101,519	126,054,487
Treasury stock, shares (in shares)	27,285	55,513

CONSOLIDATED STATEMENTS OF CASH

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	9 Months Ended
	Oct. 03, 2020	Sep. 28, 2019
Cash flows from operating activities:
Net loss	$ (484,658)	$ (17,320)
Adjustments to reconcile net loss to net cash provided by (used in) operating activities:
Depreciation and amortization	212,413	191,485
Non-cash interest expense	6,948	6,233
Share-based compensation expense	12,568	10,613
Non-cash fair value premium on purchased inventory	0	16,249
Goodwill impairment	503,171	0
Asset impairment	3,490	0
Loss (gain) on asset sales, net	710	(335)
Provision for doubtful accounts	3,762	(492)
Deferred income taxes	(27,052)	(45,192)
Changes in operating assets and liabilities, net of effect of acquisitions:
Accounts receivable	(84,309)	(138,329)
Inventories	30,980	63,327
Income taxes	16,886	1,256
Prepaid expenses and other	6,246	(4,374)
Accounts payable	22,669	8,486
Accrued expenses	12,920	(21,005)
Other, net	132	(2,783)
Net cash provided by operating activities	236,876	67,819
Cash flows from investing activities:
Acquisitions, net of cash acquired	(41,841)	(179,184)
Capital expenditures	(62,535)	(86,364)
Proceeds from sale of property, plant and equipment	1,538	873
Net cash used in investing activities	(102,838)	(264,675)
Cash flows from financing activities:
Payments on term loan	(19,215)	(12,810)
Proceeds from senior notes	500,000	0
Payments of financing costs	(6,905)	0
Payments related to tax withholding for share-based compensation	(478)	(231)
Purchases of treasury stock	(6,428)	0
Net cash provided by financing activities	396,974	156,959
Effect of exchange rate changes on cash and cash equivalents	507	1,406
Net increase (decrease) in cash, cash equivalents and restricted cash	531,519	(38,491)
Cash, cash equivalents and restricted cash at beginning of period	102,307	147,607
Cash, cash equivalents and restricted cash at end of period	633,826	109,116
Taxes paid (refunded), net	(1,881)	47,881
ABL Facility
Cash flows from financing activities:
Proceeds from line of credit	345,000	290,000
Payments on line of credit	(415,000)	(120,000)
Cash flow revolver
Cash flows from financing activities:
Proceeds from line of credit	115,000	0
Payments on line of credit	$ (115,000)	$ 0

CONSOLIDATED STATEMENTS OF STOC

CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Cumulative Effect, Period of Adoption, Adjustment	Common Stock	Additional Paid-In Capital	Retained Earnings (Deficit)	Retained Earnings (Deficit)Cumulative Effect, Period of Adoption, Adjustment	Accumulated Other Comprehensive Income (Loss)	Treasury Stock
Beginning balance (in shares) at Dec. 31, 2018			125,583,159					(110,899)
Beginning balance at Dec. 31, 2018	$ 959,982		$ 1,256	$ 1,237,056	$ (265,839)		$ (10,813)	$ (1,678)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Treasury stock purchases (in shares)								(34,724)
Treasury stock purchases	(231)							$ (231)
Retirement of treasury shares (in shares)			(84,810)					84,810
Retirement of treasury shares			$ (1)	(722)				$ 723
Issuance of restricted stock (in shares)			109,430
Issuance of restricted stock			$ 2	(2)
Issuance of common stock for the Ply Gem merger (in shares)			13,731
Issuance of common stock for the Ply Gem merger	167			167
Other comprehensive income (loss)	(25,326)						(25,326)
Deferred compensation obligation				(86)				$ 86
Deferred compensation obligation (in shares)								5,712
Share-based compensation	10,613			10,613
Net income (loss)	(17,320)				(17,320)
Ending balance (in shares) at Sep. 28, 2019			125,621,510					(55,101)
Ending balance at Sep. 28, 2019	927,885		$ 1,257	1,247,026	(283,159)		(36,139)	$ (1,100)
Beginning balance (in shares) at Jun. 29, 2019			125,588,427					(69,315)
Beginning balance at Jun. 29, 2019	908,204		$ 1,256	1,243,897	(308,323)		(27,419)	$ (1,207)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Treasury stock purchases (in shares)								(12,612)
Treasury stock purchases	(64)							$ (64)
Retirement of treasury shares (in shares)			(26,826)					26,826
Retirement of treasury shares				(171)				$ 171
Issuance of restricted stock (in shares)			46,178
Issuance of restricted stock			$ 1	(1)
Issuance of common stock for the Ply Gem merger (in shares)			13,731
Issuance of common stock for the Ply Gem merger	167			167
Other comprehensive income (loss)	(8,720)						(8,720)
Share-based compensation	3,134			3,134
Net income (loss)	25,164				25,164
Ending balance (in shares) at Sep. 28, 2019			125,621,510					(55,101)
Ending balance at Sep. 28, 2019	927,885		$ 1,257	1,247,026	(283,159)		(36,139)	$ (1,100)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative effect of accounting change		$ (678)				$ (678)
Beginning balance (in shares) at Dec. 31, 2019			126,110,000					(55,513)
Beginning balance at Dec. 31, 2019	935,318		$ 1,261	1,248,787	(281,229)		(32,398)	$ (1,103)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Treasury stock purchases (in shares)								(1,168,514)
Treasury stock purchases	(6,906)							$ (6,906)
Retirement of treasury shares (in shares)			(1,166,973)					1,166,973
Retirement of treasury shares			$ (12)	(6,883)				$ 6,895
Issuance of restricted stock (in shares)			185,777
Issuance of restricted stock			$ 2	(2)
Other comprehensive income (loss)	(35,354)						(35,354)
Deferred compensation obligation			$ 1	(593)				$ 592
Deferred compensation obligation (in shares)								29,769
Share-based compensation	12,568			12,568
Net income (loss)	(484,658)				(484,658)
Ending balance (in shares) at Oct. 03, 2020			125,128,804					(27,285)
Ending balance at Oct. 03, 2020	420,290		$ 1,252	1,253,877	(766,565)		(67,752)	$ (522)
Beginning balance (in shares) at Jul. 04, 2020			125,122,988					(25,650)
Beginning balance at Jul. 04, 2020	378,212		$ 1,252	1,249,852	(797,081)		(75,300)	$ (511)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Treasury stock purchases (in shares)								(1,635)
Treasury stock purchases	(11)							$ (11)
Issuance of restricted stock (in shares)			5,816
Other comprehensive income (loss)	7,548						7,548
Share-based compensation	4,025			4,025
Net income (loss)	30,516				30,516
Ending balance (in shares) at Oct. 03, 2020			125,128,804					(27,285)
Ending balance at Oct. 03, 2020	$ 420,290		$ 1,252	$ 1,253,877	$ (766,565)		$ (67,752)	$ (522)

SUMMARY OF SIGNIFICANT ACCOUNTI

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES	9 Months Ended
	Oct. 03, 2020
Accounting Policies [Abstract]
SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES	SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES Basis of Presentation The accompanying unaudited consolidated financial statements for Cornerstone Building Brands, Inc. (together with its subsidiaries, unless otherwise indicated, the “Company,” “Cornerstone,” “NCI”, “we,” “us” or “our”) have been prepared in accordance with generally accepted accounting principles for interim financial information and with the instructions to Form 10-Q and Article 10 of Regulation S-X. Accordingly, they do not include all of the information and notes required by generally accepted accounting principles (“GAAP”) for complete financial statements. In the opinion of management, the unaudited consolidated financial statements included herein contain all adjustments, which consist of normal recurring adjustments, necessary to fairly present the Company’s financial position, results of operations and cash flows for the periods indicated. Operating results for the period from January 1, 2020 through October 3, 2020 are not necessarily indicative of the results that may be expected for the fiscal year ending December 31, 2020. Certain reclassifications have been made to the prior period disaggregated revenue amounts in the notes to the consolidated financial statements to conform to the current presentation. The net effect of these reclassifications was not material to the consolidated financial statements (see disaggregated revenue table below). For additional information, refer to the consolidated financial statements and notes thereto included in the Company’s Annual Report on Form 10-K for the fiscal year ended December 31, 2019 filed with the Securities and Exchange Commission (the “SEC”) on March 3, 2020. On July 17, 2018, the Company entered into an Agreement and Plan of Merger (the “Merger Agreement”) with Ply Gem Parent, LLC (“Ply Gem”), and for certain limited purposes as set forth in the Merger Agreement, Clayton, Dubilier & Rice, LLC (“CD&R”), pursuant to which, at the closing of the merger, Ply Gem would be merged with and into NCI, with NCI continuing its existence as a corporation organized under the laws of the State of Delaware (the “Merger”). In connection with the Merger, 58,709,067 shares of NCI common stock were issued to the holders of all of the equity interests in Ply Gem (the “Stock Issuance”), representing approximately 47% of the total number of shares of NCI Common Stock outstanding following the consummation of the Merger on November 16, 2018. There are approximately 57,103 shares of NCI Common Stock of the original 58,709,067 that have not yet been issued pending holder identification and have been accrued as purchase consideration within other current liabilities in the consolidated balance sheet at October 3, 2020. Reporting Periods The Company’s current fiscal quarters are based on a four-four-five week calendar with periods ending on the Saturday of the last week in the quarter except that December 31st will always be the year-end date. Therefore, the financial results of certain fiscal quarters may not be comparable to prior fiscal quarters. Restricted Cash The following table provides a reconciliation of cash, cash equivalents and restricted cash reported within the consolidated balance sheets that total the amounts shown in the consolidated statements of cash flows (in thousands): October 3, December 31, Cash and cash equivalents $ 627,603 $ 98,386 Restricted cash (1) 6,223 3,921 Total cash, cash equivalents and restricted cash shown in the consolidated statements of cash flows $ 633,826 $ 102,307 (1) Restricted cash primarily relates to escrow balances held for an outstanding earn-out agreement and working capital and other indemnification agreements. Accounts Receivables and Related Allowance The Company reports accounts receivable net of the allowance for expected credit losses. Trade accounts receivable are the result of sales of metal building products, insulated metal panels, metal coating, vinyl siding, metal siding, injection molded products, vinyl windows, aluminum windows, and other products and services to customers throughout the United States and Canada and affiliated territories, including international builders who resell to end users. Sales are primarily denominated in U.S. dollars. Credit sales do not normally require a pledge of collateral; however, various types of liens may be filed to enhance the collection process and we require payment prior to shipment for certain international shipments. The Company establishes reserves for doubtful accounts on a customer by customer basis when we believe the required payment of specific amounts owed is unlikely to occur. Bad debt provisions are included in selling, general and administrative expenses. In establishing these reserves, the Company considers changes in the financial position of a customer, availability of security, unusual macroeconomic conditions, lien rights and bond rights as well as disputes, if any, with our customers. Our allowance for doubtful accounts reflects reserves for customer receivables to reduce receivables to amounts expected to be collected. We determine past due status as of the contractual payment date. Interest on delinquent accounts receivable is included in the trade accounts receivable balance and recognized as interest income when earned and collectability is reasonably assured. Uncollectible accounts are written off when a settlement is reached for an amount that is less than the outstanding historical balance, all collection efforts have been exhausted and/or any legal action taken by the Company has concluded. The following table represents the rollforward of the reserve for uncollectible accounts for the periods indicated (in thousands): Nine Months Ended October 3, 2020 Ending balance, December 31, 2019 $ 9,962 Cumulative effect of accounting change (1) 678 Provision for expected credit losses 3,762 Amounts charged against allowance for credit losses, net of recoveries (1,801) Allowance for credit losses of acquired company at date of acquisition 810 Ending balance, October 3, 2020 $ 13,411 (1) Cumulative effect of accounting change reflects the modified retrospective effect of adopting ASU 2016-13 Financial Instruments—Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments (See Note 2 — Accounting Pronouncements ) . Net Sales The Company adopted Accounting Standards Update (“ASU”) No. 2014-09, Revenue from Contracts with Customers (“ASU 2014-09”), as of October 29, 2018. ASU 2014-09 provides enhancements to the quality and consistency of how revenue is reported while also improving comparability in the financial statements of companies reporting using International Financial Reporting Standards and GAAP. The core principle of this update is that an entity should recognize revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. The Company enters into contracts that pertain to products, which are accounted for as separate performance obligations and are typically one year or less in duration. The Company does not exercise significant judgment in determining the timing for the satisfaction of performance obligations or the transaction price. Revenue is measured as the amount of consideration expected to be received in exchange for our products. The Company has elected to apply the practical expedient provided for in ASU No. 2014-09 and has not disclosed information regarding remaining performance obligations that have original expected durations of one year or less. Revenue is generally recognized when the product has shipped from our facility and control has transferred to the customer. For a portion of our business, when we process customer owned material, control is deemed to transfer to the customer as the processing is being completed. Our revenues are adjusted for variable consideration, which includes customer volume rebates and prompt payment discounts. We measure variable consideration by estimating expected outcomes using analysis and inputs based upon anticipated performance, historical data, and current and forecasted information. Customer returns are recorded as a reduction to sales on an actual basis throughout the year and also include an estimate at the end of each reporting period for future customer returns related to sales recorded prior to the end of the period. The Company generally estimates customer returns based upon the time lag that historically occurs between the sale date and the return date while also factoring in any new business conditions that might impact the historical analysis such as new product introduction. Measurement of variable consideration is reviewed by management periodically and revenue is adjusted accordingly. We do not have significant financing components. Shipping and handling activities performed by us are considered activities to fulfill the sales of our products. Amounts billed for shipping and handling are included in net sales, while costs incurred for shipping and handling are included in cost of sales. In accordance with certain contractual arrangements, we receive payment from our customers in advance related to performance obligations that are to be satisfied in the future and recognize such payments as deferred revenue, primarily related to the Company's weathertightness warranties (see Note 12 — Warranty). The following table presents disaggregated revenue disclosure details of net sales by segment (in thousands): Three Months Ended Nine Months Ended October 3, September 28, October 3, September 28, Windows Net Sales Disaggregation: Vinyl windows (1) $ 465,472 $ 473,202 $ 1,283,337 $ 1,334,747 Aluminum windows (1) 22,056 18,404 61,338 56,490 Other (1) 13,786 12,732 33,364 43,342 Total $ 501,314 $ 504,338 $ 1,378,039 $ 1,434,579 Siding Net Sales Disaggregation: Vinyl siding $ 146,585 $ 148,912 $ 387,559 $ 400,220 Metal 75,477 75,933 192,567 199,265 Injection molded 20,460 17,429 49,556 47,163 Stone 20,988 32,254 61,999 70,441 Other products & services 58,388 41,271 156,509 123,512 Total $ 321,898 $ 315,799 $ 848,190 $ 840,601 Commercial Net Sales Disaggregation: Metal building products $ 281,339 $ 320,028 $ 842,863 $ 914,623 Insulated metal panels 89,088 109,322 260,410 332,403 Metal coil coating 33,614 35,556 96,498 123,126 Total $ 404,041 $ 464,906 $ 1,199,771 $ 1,370,152 Total Net Sales: $ 1,227,253 $ 1,285,043 $ 3,426,000 $ 3,645,332 (1) Aluminum windows and other net sales for the three months ended September 28, 2019 includes $6.5 million and $1.4 million, respectively, of net sales previously included in vinyl windows. Aluminum windows and other net sales for the nine months ended September 28, 2019 includes $16.8 million and $3.8 million, respectively, of net sales previously included in vinyl windows.

ACCOUNTING PRONOUNCEMENTS

ACCOUNTING PRONOUNCEMENTS	9 Months Ended
	Oct. 03, 2020
Accounting Standards Update and Change in Accounting Principle [Abstract]
ACCOUNTING PRONOUNCMENTS	ACCOUNTING PRONOUNCEMENTS Adopted Accounting Pronouncements In June 2016, the Financial Accounting Standards Board ("FASB") issued ASU 2016-13 Financial Instruments—Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments. This ASU requires an entity to measure all expected credit losses for financial assets, including trade receivables, held at the reporting date based on historical experience, current conditions, and reasonable and supportable forecasts. Entities will now incorporate forward-looking information based on expected losses to estimate credit losses. Effective January 1, 2020, the Company adopted this guidance on a modified retrospective basis, pursuant to which it recorded a $0.7 million adjustment to increase the opening balance of accumulated deficit as of January 1, 2020 for the impact of applying the new standard. The adjustment related to recording an incremental credit loss to the accounts receivable allowance for doubtful accounts at the beginning of the first period in which the accounting standard is effective. Additional credit loss disclosures are included in Note 1 — Summary of Significant Accounting Policies . In August 2018, the FASB issued ASU 2018-13, Fair Value Measurement (Topic 820): Disclosure Framework—Changes to the Disclosure Requirements for Fair Value Measurement, which modifies disclosure requirements for fair value measurements under FASB Accounting Standards Codification ("ASC") 820, Fair Value Measurement. Effective January 1, 2020, the Company adopted this guidance. The application of ASU 2018-13 did not have a material effect on consolidated financial statements. In August 2018, the FASB issued ASU 2018-14, Compensation—Retirement Benefits—Defined Benefit Plans—General (Subtopic 715-20): Disclosure Framework—Changes to the Disclosure Requirements for Defined Benefit Plans , which removes disclosures no longer considered cost beneficial, clarifies the specific requirements of disclosures and adds disclosure requirements identified as relevant. Effective January 1, 2020, the Company adopted this guidance. The application of ASU 2018-14 did not have a material effect on consolidated financial statements. Recent Accounting Pronouncements In December 2019, the FASB issued ASU 2019-12, Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes, which simplifies the accounting for income taxes by removing certain exceptions to the general principles in Topic 740 and also improves consistent application of and simplifies GAAP for other areas of Topic 740 by clarifying and amending existing guidance. The Company will be required to adopt this guidance in the annual and interim periods for our fiscal year ending December 31, 2021, with early adoption permitted. The Company is evaluating the impact of adopting this guidance. In March 2020, the FASB issued ASU 2020-04, Reference Rate Reform (Topic 848): Facilitation of the Effects of Reference Rate Reform on Financial Reporting , which provides optional guidance to ease the potential burden in accounting for reference rate reform on financial reporting. The amendments in this ASU are elective, apply to all entities that have contracts, hedging relationships, and other transactions that reference LIBOR or another reference rate expected to be discontinued because of rate reform, and are effective as of March 12, 2020 through December 31, 2022. The Company is evaluating the impact of electing to apply the amendments in this guidance. Additionally, there were various other accounting standards and interpretations issued that the Company has not yet been required to adopt, none of which is expected to have a material impact on the Company’s consolidated financial statements going forward.

ACQUISITIONS

ACQUISITIONS	9 Months Ended
	Oct. 03, 2020
Business Combinations [Abstract]
ACQUISITIONS	ACQUISITIONS Kleary Acquisition On March 2, 2020, the Company acquired 100% of the issued and outstanding shares of the common stock of Kleary Masonry, Inc. ("Kleary") for total consideration of $40.0 million, exclusive of the $2.0 million working capital adjustment that was finalized during the three months ended July 4, 2020. The transaction was financed with cash on hand and through borrowings under the Company’s asset-based revolving credit facility. Kleary primarily services residential customers with manufactured stone installations and commercial customers with manufactured wall installations in the Sacramento, California area. Kleary's results are reported within the Siding business segment. The acquisition of Kleary strengthens the Company's position as a market leader in stone veneer. The Company accounted for the transaction as an acquisition in accordance with the provisions of ASC 805, Business Combinations , which results in a new valuation for the assets and liabilities of Kleary based upon fair values as of the closing date. The Company determined the fair value of the tangible and intangible assets and the liabilities acquired, and recorded goodwill based on the excess of the fair value of the acquisition consideration over such fair values, as follows (in thousands): Assets acquired: Cash $ 143 Accounts receivable 7,235 Inventories 670 Prepaid expenses and other current assets 277 Property, plant and equipment 1,042 Lease right of use assets 445 Intangible assets (trade names/customer relationships) 22,350 Goodwill 11,721 Other assets 680 Total assets acquired 44,563 Liabilities assumed: Accounts payable 1,126 Other accrued expenses 1,005 Lease liabilities 339 Other long-term liabilities 109 Total liabilities assumed 2,579 Net assets acquired $ 41,984 The $11.7 million of goodwill was allocated to the Siding segment and is expected to be deductible for tax purposes. The goodwill is attributable to the workforce of the acquired business and the synergies expected to be realized. During the three and nine months ended October 3, 2020, the Company incurred $6.9 million and $8.1 million, respectively, of acquisition-related costs for Kleary, primarily consisting of a contingent earnout, wh ich are recorded in strategic development and acquisition related costs in the Company’s consolidated statements of operations. The final acquisition accounting allocation for the acquisition of Kleary remains subject to further adjustments. The specific accounts subject to ongoing acquisition accounting adjustments include accounts receivable, inventories, prepaid expenses and other current assets, goodwill, intangibles, accounts payable, accrued expenses, accrued warranties and other liabilities. Therefore, the measurement period remained open as of October 3, 2020, and the preliminary acquisition accounting allocation detailed above is subject to further adjustment. The Company anticipates completing these acquisition accounting adjustments during the first quarter of fiscal 2021. Unaudited Pro Forma Financial Information During the three and nine months ended October 3, 2020, Kleary contributed net sales of $13.3 million and $25.9 million, respectively, a net loss of $0.9 million and net income of $0.8 million, respectively, which has been included within the Company’s consolidated statement of operations. The following table provides unaudited supplemental pro forma results for Cornerstone, prepared in accordance with ASC 805, for the three and nine months ended October 3, 2020 and September 28, 2019 as if the Kleary and ESW (defined below) acquisitions had occurred on January 1, 2019 (in thousands except for per share data): Three Months Ended Nine Months Ended October 3, September 28, October 3, September 28, Net sales $ 1,227,253 $ 1,298,307 $ 3,434,358 $ 3,694,102 Net income (loss) applicable to common shares 30,516 25,164 (482,789) (19,843) Net income (loss) per common share: Basic $ 0.24 $ 0.20 $ (3.84) $ (0.16) Diluted $ 0.24 $ 0.20 $ (3.84) $ (0.16) The unaudited supplemental pro forma financial information was prepared based on the historical information of Cornerstone, Environmental Stoneworks and Kleary. The unaudited supplemental pro forma financial information does not give effect to the potential impact of current financial conditions, any anticipated synergies, operating efficiencies or cost savings that may result from the two acquisitions or any integration costs. Unaudited pro forma balances are not necessarily indicative of operating results had the Environmental Stoneworks and Kleary acquisitions occurred on January 1, 2019 or of future results. Environmental Stoneworks On January 12, 2019, the Company entered into a Unit Purchase Agreement (the “Purchase Agreement”) with Environmental Materials, LLC, a Delaware limited liability company (“ESW”), the Members of Environmental Materials, LLC (the “Sellers”) and Charles P. Gallagher and Wayne C. Kocourek, solely in their capacity as the Seller Representative (as defined in the Purchase Agreement), pursuant to which, on February 20, 2019, the Company’s wholly-owned subsidiary, Ply Gem Industries, Inc., purchased from the Sellers 100% of the outstanding limited liability company interests of ESW (the “Environmental Stoneworks Acquisition”) for total consideration of $182.6 million, subject to certain post-closing adjustments, for ESW. The transaction was financed through borrowings under the Company’s asset-based revolving credit facility. The Environmental Stoneworks Acquisition, when combined with the Company’s existing stone businesses, positions the Company as a market leader in stone veneer. The Company accounted for the transaction as an acquisition in accordance with the provisions of ASC Topic 805, Business Combinations , which results in a new valuation for the assets and liabilities of ESW based upon fair values as of the closing date. The Company determined the fair value of the tangible and intangible assets and the liabilities acquired, and recorded goodwill based on the excess of the fair value of the acquisition consideration over such fair values, as follows (in thousands): Assets acquired: Restricted cash $ 3,379 Accounts receivable 16,825 Inventories 13,062 Prepaid expenses and other current assets 3,677 Property, plant and equipment 14,295 Lease right of use assets 11,372 Intangible assets (trade names/customer relationships) 91,170 Goodwill 63,543 Deferred taxes 474 Other assets 157 Total assets acquired 217,954 Liabilities assumed: Accounts payable 5,910 Other accrued expenses 14,666 Lease liabilities 11,365 Other long-term liabilities 3,450 Total liabilities assumed 35,391 Net assets acquired $ 182,563

RESTRUCTURING

RESTRUCTURING	9 Months Ended
	Oct. 03, 2020
Restructuring and Related Activities [Abstract]
RESTRUCTURING	RESTRUCTURING The Company has various initiatives and programs in place within its business units to reduce selling, general, and administrative expenses ("SG&A"), manufacturing costs and to optimize the Company's combined manufacturing footprint. During the nine months ended October 3, 2020, the Company incurred restructuring charges of $7.2 million, $2.9 million and $20.4 million in the Windows, Siding and Commercial segments, respectively, and $1.8 million in restructuring charges at Corporate headquarters. Restructuring charges incurred to date since inception of the current restructuring initiatives began in 2019 are $50.4 million. The following table summarizes our restructuring plan costs and charges related to the restructuring plans for the period indicated, which are recorded in restructuring and impairment charges in the Company’s consolidated statements of operations (in thousands): Three Months Ended Nine Months Ended October 3, 2020 October 3, 2020 Severance $ 1,074 $ 23,563 Asset impairments 1,169 4,938 Other restructuring costs 675 3,820 Total restructuring costs $ 2,918 $ 32,321 For the nine months ended October 3, 2020, $32.1 million of restructuring costs are recorded within restructuring and impairment costs and $0.2 million are recorded within cost of goods sold, in the Company’s consolidated statement of operations. The asset impairments of $4.9 million for the nine months ended October 3, 2020 are comprised primarily of equipment costs of $3.4 million and right of use asset impairments of $1.5 million related predominantly to the closure of the Company's Ambridge, Pennsylvania Commercial facility. The following table summarizes our severance liability and cash payments made pursuant to the restructuring plans from inception through October 3, 2020 (in thousands): Windows Siding Commercial Corporate Total Balance, December 31, 2018 $ — $ 85 $ — $ 2,333 $ 2,418 Costs incurred 1,094 1,834 2,721 4,009 9,658 Cash payments (676) (1,437) (2,721) (4,579) (9,413) Balance, December 31, 2019 $ 418 $ 482 $ — $ 1,763 $ 2,663 Costs incurred 3,389 2,367 16,413 1,394 23,563 Cash payments (3,368) (2,169) (14,314) (1,394) (21,245) Balance, October 3, 2020 $ 439 $ 680 $ 2,099 $ 1,763 $ 4,981 These severance liabilities are included within other accrued expenses on the consolidated balance sheets.

GOODWILL

GOODWILL	9 Months Ended
	Oct. 03, 2020
Goodwill and Intangible Assets Disclosure [Abstract]
GOODWILL	GOODWILL The Company’s goodwill balance and changes in the carrying amount of goodwill by segment follows (in thousands): Windows Siding Commercial Total Balance, December 31, 2019 $ 714,023 $ 807,280 $ 148,291 $ 1,669,594 Goodwill recognized from Kleary Acquisition — 11,721 — 11,721 Impairment (320,990) (176,774) (5,407) (503,171) Currency translation 1,885 7,081 — 8,966 Purchase accounting adjustments — 2,882 — 2,882 Balance, October 3, 2020 $ 394,918 $ 652,190 $ 142,884 $ 1,189,992 The Company performs an annual impairment assessment of goodwill and indefinite-lived intangibles. Additionally, we assess goodwill and indefinite-lived intangibles for impairment whenever events or changes in circumstances indicate that the fair values may be below the carrying values of such assets. The Company performs these annual and interim impairment tests at the following levels: Windows, Siding, Metal Coil Coating, Engineered Building Products, Metal Components, and Insulated Metal Panels. Unforeseen events, changes in circumstances and market conditions and material differences in the value of intangible assets due to changes in estimates of future cash flows could negatively affect the fair value of our assets and result in a non-cash impairment charge. Some factors considered important that could trigger an impairment review include the following: significant underperformance relative to expected historical or projected future operating results, significant changes in the manner of our use of the acquired assets or the strategy for our overall business, significant declines in stock price for a sustained period, and significant sustained negative industry or economic trends. The fair value of the Company's reporting units is based on a blend of estimated discounted cash flows and publicly traded company multiples. A significant reduction in projected sales and earnings which would lead to a reduction in future cash flows could indicate potential impairment. The results from each of these models are then weighted and combined into a single estimate of fair value for the Company's reporting units. Estimated discounted cash flows are based on projected sales and related cost of sales. Publicly traded company multiples and acquisition multiples are derived from information on traded shares and analysis of recent acquisitions in the marketplace, respectively, for companies with operations similar to ours. The primary assumptions used in these various models include earnings multiples of acquisitions in a comparable industry, future cash flow estimates of each of the reporting units, weighted average cost of capital, working capital and capital expenditure requirements. As a result of the decline in the Company’s market valuation and near-term economic uncertainties related to the COVID-19 pandemic, during the first quarter of fiscal 2020, the Company determined that an interim goodwill impairment test was necessary. The Company determined that deterioration in discount rates and market multiples during the three months ended April 4, 2020 from the COVID-19 driven economic uncertainty when combined with lower forecasted discounted cash flows, decreased the fair values of the Company’s reporting units. The Company performed an impairment evaluation by comparing the fair market value of its reporting units, as determined using an equally weighted discounted cash flow model and market approach, to its carrying value. It was determined that the Siding, Windows and Metal Coil Coating reporting units' carrying value each exceeded their fair value. As a result of this analysis, the Company recorded a goodwill impairment charge of approximately $321.0 million for the Windows reporting unit, $176.8 million for the Siding reporting unit, and $5.4 million for the Metal Coil Coating reporting unit (which is within the Commercial segment). This non-cash charge does not affect the Company’s cash position, liquidity or debt covenant compliance, nor will it have any impact on future operations. However, there can be no assurance that: 1) valuation multiples will not decline, 2) discount rates will not increase, or 3) the earnings, book values or projected earnings and cash flows of the Company’s reporting units will not decline. The Company will continue to analyze changes to these assumptions in future periods. There were no additional impairment triggers identified during the nine months ended October 3, 2020. The Company will continue to perform its required annual goodwill impairment test during the fourth quarter and further declines in the Company's end markets could result in additional goodwill impairment charges. In addition to ASC 350, Intangibles-goodwill and other , the Company evaluated its property and equipment and intangible assets for impairment during the first quarter of fiscal 2020 in accordance with ASC 360, Property, plant and equipment . This analysis was triggered by a decrease in projected cash flows due to the depressed construction market. The impairment test results did not indicate that an impairment existed at April 4, 2020 other than the $3.1 million included in restructuring and impairment charges, net, in the Company's consolidated statement of operations for the three months ended April 4, 2020. There were no additional impairment triggers identified during the nine months ended October 3, 2020.

INVENTORIES

INVENTORIES	9 Months Ended
	Oct. 03, 2020
Inventory Disclosure [Abstract]
INVENTORIES	INVENTORIES The components of inventory are as follows (in thousands): October 3, 2020 December 31, 2019 Raw materials $ 232,627 $ 239,063 Work in process and finished goods 176,270 200,131 Total inventory $ 408,897 $ 439,194 As of October 3, 2020, the Company had inventory purchase commitments of $21.2 million.

INTANGIBLES

INTANGIBLES	9 Months Ended
	Oct. 03, 2020
Goodwill and Intangible Assets Disclosure [Abstract]
INTANGIBLES	INTANGIBLES The table that follows presents the major components of intangible assets as of October 3, 2020 and December 31, 2019 (in thousands): Range of Life (Years) Weighted Average Amortization Period (Years) Cost Accumulated Amortization Net Carrying Value As of October 3, 2020 Amortized intangible assets: Trademarks/Trade names 5 – 15 8 $ 248,021 $ (51,658) $ 196,363 Customer lists and relationships 7 – 20 10 1,754,347 (327,577) 1,426,770 Total intangible assets 10 $ 2,002,368 $ (379,235) $ 1,623,133 As of December 31, 2019 Amortized intangible assets: Trademarks/Trade names 5 – 15 9 $ 252,942 $ (38,010) $ 214,932 Customer lists and relationships 9 – 20 11 1,737,060 (211,292) 1,525,768 Total intangible assets 10 $ 1,990,002 $ (249,302) $ 1,740,700

ASSETS HELD FOR SALE

ASSETS HELD FOR SALE	9 Months Ended
	Oct. 03, 2020
Property, Plant and Equipment Assets Held-for-sale Disclosure [Abstract]
ASSETS HELD FOR SALE	ASSETS HELD FOR SALE We record assets held for sale at the lower of the carrying value or fair value less costs to sell. The following criteria are used to determine if property is held for sale: (i) management has the authority and commits to a plan to sell the property; (ii) the property is available for immediate sale in its present condition; (iii) there is an active program to locate a buyer and the plan to sell the property has been initiated; (iv) the sale of the property is probable within one year; (v) the property is being actively marketed at a reasonable sale price relative to its current fair value; and (vi) it is unlikely that the plan to sell will be withdrawn or that significant changes to the plan will be made. In determining the fair value of the assets less cost to sell, we consider factors including current sales prices for comparable assets in the area, recent market analysis studies, appraisals and any recent legitimate offers. If the estimated fair value less cost to sell of an asset is less than its current carrying value, the asset is written down to its estimated fair value less cost to sell. The total carrying value of assets held for sale was $5.1 million and $1.8 million as of October 3, 2020 and December 31, 2019, respectively. Assets held for sale at October 3, 2020 are actively marketed for sale or were under contract. During the three and nine months ended October 3, 2020, the Company reclassified certain facilities within the Commercial segment that have a net book value of $4.3 million to assets held for sale. Additionally, during the nine months ended October 3, 2020, the Company acquired certain real property assets of $0.8 million through its executive relocation program which are classified as held for sale as of October 3, 2020. During the three and nine months ended October 3, 2020, the Company sold certain real property assets with a net book value of $1.8 million which had previously been classified as held for sale. In connection with the sale, the Company recognized a net loss of $0.4 million which is included in Corporate restructuring and impairment charges, net, in the consolidated statements of operations for the three and nine months ended October 3, 2020. Due to uncertainties in the estimation process, actual results could differ from the estimates used in our historical analysis. Our assumptions about property sales prices require significant judgment because the current market is highly sensitive to changes in economic conditions. We determined the estimated fair values of assets held for sale based on current market conditions and assumptions made by management, which may differ from actual results and may result in impairments if market conditions deteriorate. Certain assets held for sale are valued at fair value and are measured at fair value on a nonrecurring basis. Assets held for sale are reported at fair value, if, on an individual basis, the fair value of the asset is less than carrying value. The fair value of assets held for sale is estimated using Level 3 inputs, such as broker quotes for like-kind assets or other market indications of a potential selling value that approximates fair value. Assets held for sale, reported at fair value, less costs to sell, totaled $0.8 million as of October 3, 2020.

LEASES

LEASES	9 Months Ended
	Oct. 03, 2020
Leases [Abstract]
LEASES	LEASESThe Company leases certain manufacturing, warehouse and distribution locations, vehicles and equipment, including fleet vehicles. Many of these leases have options to terminate prior to or extend beyond the end of the term. The exercise of the majority of lease renewal options is at the Company’s sole discretion. Some lease agreements have variable payment terms, the majority of these are real estate agreements in which future increases in rent are based on an index. Lease agreements do not contain any material residual value guarantees or material restrictive covenants. Operating lease liabilities are recognized based on the present value of the future minimum lease payments over the reasonably expected holding period at commencement date. Few of the Company’s lease contracts provide a readily determinable implicit rate. For lease contracts without a readily determinable implicit rate, an estimated incremental borrowing rate (“IBR”) is utilized, based on information available at the inception of the lease. The IBR represents an estimate of the interest rate we would incur at lease commencement to borrow an amount equal to the lease payments on a collateralized basis over the term of the lease. Weighted average information about the Company’s lease portfolio as of October 3, 2020 was as follows: Weighted-average remaining lease term 5.5 years Weighted-average IBR 6.08 % Operating lease costs were as follows (in thousands): Three Months Ended Nine Months Ended October 3, September 28, October 3, September 28, Operating lease costs Fixed lease costs $ 21,220 $ 23,903 $ 78,183 $ 77,125 Variable lease costs (1) 19,013 8,654 54,188 27,868 (1) Includes short-term lease costs, which are immaterial. Cash and non-cash activities were as follows (in thousands): Three Months Ended Nine Months Ended October 3, September 28, October 3, September 28, Cash paid for amounts included in the measurement of lease liabilities: Operating cash flows for operating leases $ 24,853 $ 23,463 $ 80,241 $ 66,936 Right-of-use assets obtained in exchange for new operating lease liabilities $ 2,070 $ 47,236 $ 18,940 $ 372,269 Future minimum lease payments under non-cancelable leases as of October 3, 2020 were as follows (in thousands): Operating Leases 2020 (excluding the nine months ended October 3, 2020) $ 17,730 2021 82,979 2022 67,882 2023 42,451 2024 31,875 Thereafter 88,848 Total future minimum lease payments 331,765 Less: interest 51,911 Present value of future minimum lease payments $ 279,854 As of October 3, 2020 Current portion of lease liabilities $ 69,408 Long-term portion of lease liabilities 210,446 Total $ 279,854

SHARE-BASED COMPENSATION

SHARE-BASED COMPENSATION	9 Months Ended
	Oct. 03, 2020
Share-based Payment Arrangement [Abstract]
SHARE-BASED COMPENSATION	SHARE-BASED COMPENSATION Our 2003 Long-Term Stock Incentive Plan, as amended (the “Incentive Plan”), is an equity-based compensation plan that allows us to grant a variety of types of awards, including stock options, restricted stock awards, stock appreciation rights, cash awards, phantom stock awards, restricted stock unit awards ("RSUs") and long-term incentive awards with performance conditions (“performance share units” or "PSUs"). Awards are generally granted once per year, with the amounts and types of awards determined by the Compensation Committee of our Board of Directors (the “Committee”). In connection with the Merger with Ply Gem Parent, LLC ("Ply Gem"), on November 16, 2018 awards were granted to certain senior executives and key employees (the “Founders Awards”), which included stock options, RSUs, and PSUs. A portion of the Founders Awards was not granted under the Incentive Plan but was instead granted pursuant to a separate equity-based compensation plan, the Long-Term Incentive Plan consisting of award agreements for select Founders Awards. However, these awards were subject to the same terms and provisions as awards of the same type granted under the Incentive Plan. As of October 3, 2020, and for all periods presented, the Founders Awards and our share-based awards under the Incentive Plan have consisted of RSUs, PSUs and stock option grants, none of which can be settled through cash payments. Both our stock options and restricted stock awards are subject only to vesting requirements based on continued employment at the end of a specified time period and typically vest in annual increments over three As a general rule, option awards terminate on the earlier of (i) 10 years from the date of grant, (ii) 60 days after termination of employment or service for a reason other than death, disability or retirement, or (iii) 180 days after death, disability or retirement. Awards are non-transferable except by disposition on death or to certain family members, trusts and other family entities as the Committee may approve. Awards may be paid in cash, shares of our Common Stock or a combination, in lump sum or installments and currently or by deferred payment, all as determined by the Committee. Our time-based restricted stock awards are typically subject to graded vesting over a service period, which is three Vesting of the PSUs granted in the Founders Awards is contingent upon the achievement of synergies captured from the Merger and continued employment during a three-year performance period beginning on the grant date. At the end of the performance period, the number of actual shares to be awarded varies between 0% and 200% of target amounts. Vesting of the PSUs granted during the nine months ended October 3, 2020 is contingent upon achievement of a cumulative three-year EBITDA growth target with an additional modifier based on total shareholder return. The grant-date fair value of the PSUs granted during the nine months ended October 3, 2020 was determined by a lattice model valuation. The PSUs vest pro rata if an executive’s employment terminates after 50% of the service period has passed and prior to the end of the performance period due to death, disability, or termination by the Company without cause or by the executive for good reason. If an executive’s employment terminates for any other reason prior to the end of the performance period, all outstanding unvested PSUs, whether earned or unearned, are forfeited and cancelled. If a change in control of the Company occurs, and the plan is not accepted by the successor entity, prior to the end of the performance period, the PSU payout is calculated and paid assuming that the maximum benefit had been achieved. If the plan is accepted, awards will continue to vest as RSUs with a double trigger acceleration upon termination by the Company without cause or by the executive for good reason. If an executive’s employment terminates due to death or disability while any of the restricted stock is unvested, then all of the unvested restricted stock shall become vested. If an executive’s employment is terminated by the Company without cause or by the executive for good reason, the unvested restricted stock is forfeited. If a change in control of the Company occurs, and the plan is not accepted by the successor entity, prior to the end of the performance period, the restricted stock fully vests. If the plan is accepted, awards will continue to vest with a double trigger acceleration upon termination by the Company without cause or by the executive for good reason. The fair value of the awards is based on the Company’s stock price as of the date of grant. Stock option awards During the nine months ended October 3, 2020 and September 28, 2019, we granted 1.1 million and 0.4 million stock options, respectively. The average grant date fair value of options granted during the nine months ended October 3, 2020 and September 28, 2019 was $2.13 and $1.97 per share, respectively. No options were exercised during the nine months ended October 3, 2020 and September 28, 2019. Restricted stock units and performance share units Annual awards to our key employees generally have a three-year performance period. The fair value of RSUs awarded is based on the Company’s stock price as of the date of grant. During the nine months ended October 3, 2020, we granted RSUs to key employees with a fair value of $7.0 million representing approximately 1.4 million shares. During the nine months ended September 28, 2019, we granted RSUs to key employees with a fair value of $2.8 million, representing 0.5 million shares. During the nine months ended October 3, 2020 and September 28, 2019, we granted PSUs with a total fair value of approximately $5.6 million and $0.4 million, respectively, to key employees. Share-based compensation expense During the three and nine months ended October 3, 2020, we recorded share-based compensation expense for all awards of $4.0 million and $12.6 million, respectively. During the three and nine months ended September 28, 2019, we recorded share-based compensation expense for all awards of $3.1 million and $10.6 million, respectively.

EARNINGS PER COMMON SHARE

EARNINGS PER COMMON SHARE	9 Months Ended
	Oct. 03, 2020
Earnings Per Share [Abstract]
EARNINGS PER COMMON SHARE	EARNINGS PER COMMON SHARE Basic earnings per common share is computed by dividing net income allocated to common shares by the weighted average number of common shares outstanding. Diluted earnings per common share, if applicable, considers the dilutive effect of common stock equivalents. The reconciliation of the numerator and denominator used for the computation of basic and diluted earnings per common share is as follows (in thousands, except per share data): Three Months Ended Nine Months Ended October 3, September 28, October 3, September 28, Numerator for Basic and Diluted Earnings Per Common Share Net income (loss) applicable to common shares $ 30,028 $ 24,790 $ (484,658) $ (17,320) Denominator for Basic and Diluted Earnings Per Common Share Weighted average basic number of common shares outstanding 125,100 125,557 125,655 125,526 Common stock equivalents: Employee stock options 189 1 — — PSUs and Performance Share Awards — — — — Weighted average diluted number of common shares outstanding 125,289 125,558 125,655 125,526 Basic income (loss) per common share $ 0.24 $ 0.20 $ (3.86) $ (0.14) Diluted income (loss) per common share $ 0.24 $ 0.20 $ (3.86) $ (0.14) Incentive Plan securities excluded from dilution (1) 2,146 5,189 3,338 4,974 (1) Represents securities not included in the computation of diluted earnings per common share because their effect would have been anti-dilutive. We calculate earnings per share using the “two-class” method, whereby unvested share-based payment awards that contain nonforfeitable rights to dividends or dividend equivalents are “participating securities” and, therefore, these participating securities are treated as a separate class in computing earnings per share. The calculation of earnings per share presented here excludes the income attributable to unvested restricted stock units related to our Incentive Plan from the numerator and excludes the dilutive impact of those shares from the denominator. Awards subject to the achievement of performance conditions or market conditions for which such conditions had been met at the end of any of the fiscal periods presented are included in the computation of diluted earnings per common share if their effect was dilutive.

WARRANTY

WARRANTY	9 Months Ended
	Oct. 03, 2020
Product Warranties Disclosures [Abstract]
WARRANTY	WARRANTY The Company sells a number of products and offers a number of warranties. The specific terms and conditions of these warranties vary depending on the product sold. The Company's warranty liabilities are undiscounted and adjusted for inflation based on third party actuarial estimates. Factors that affect the Company’s warranty liabilities include the number of units sold, historical and anticipated rates of warranty claims, cost per claim and new product introduction. Warranties are normally limited to replacement or service of defective components for the original customer. Some warranties are transferable to subsequent owners and are generally limited to ten years from the date of manufacture or require pro-rata payments from the customer. A provision for estimated warranty costs is recorded based on historical experience and the Company periodically adjusts these provisions to reflect actual experience. Warranty costs are included within cost of goods sold. The Company assesses the adequacy of the recorded warranty claims and adjusts the amounts as necessary. Separately, upon the sale of a weathertightness warranty in the Commercial segment, the Company records the resulting revenue as deferred revenue, which is included in other accrued expenses and other long-term liabilities on the consolidated balance sheets depending on when the revenues are expected to be recognized. The following table represents the rollforward of our accrued warranty obligation and deferred warranty revenue activity for the nine months ended October 3, 2020 and September 28, 2019 (in thousands): Nine Months Ended October 3, 2020 September 28, 2019 Beginning balance $ 216,173 $ 134,515 Acquisition 109 — Purchase accounting adjustments — 84,280 Warranties sold 1,885 2,313 Revenue recognized (2,054) (2,075) Expense 23,257 22,006 Settlements (22,645) (22,285) Ending balance 216,725 218,754 Less: current portion 27,201 31,294 Total, less current portion $ 189,524 $ 187,460 The current portion of the warranty liabilities are recorded within other accrued expenses and the long-term portion of the warranty liabilities are recorded within other long-term liabilities in the Company’s consolidated balance sheets.

DEFINED BENEFIT PLANS

DEFINED BENEFIT PLANS	9 Months Ended
	Oct. 03, 2020
Retirement Benefits [Abstract]
DEFINED BENEFIT PLANS	DEFINED BENEFIT PLANS RCC Pension Plan — With the acquisition of Robertson-Ceco II Corporation (“RCC”) on April 7, 2006, we assumed a defined benefit plan (the “RCC Pension Plan”). Benefits under the RCC Pension Plan are primarily based on years of service and the employee’s compensation. The RCC Pension Plan is frozen and, therefore, employees do not accrue additional service benefits. Plan assets of the RCC Pension Plan are invested in broadly diversified portfolios of government obligations, mutual funds, stocks, bonds, fixed income securities and master limited partnerships. CENTRIA Benefit Plans — As a result of the CENTRIA Acquisition on January 16, 2015, we assumed noncontributory defined benefit plans covering certain hourly employees (the “CENTRIA Benefit Plans”) which are closed to new participants. Benefits under the CENTRIA Benefit Plans are calculated based on fixed amounts for each year of service rendered, although benefits accruals for one of the plans previously ceased. Plan assets of the CENTRIA Benefit Plans are invested in broadly diversified portfolios of domestic and international equity mutual funds, bonds, mortgages and other funds. CENTRIA also sponsors postretirement medical and life insurance plans that cover certain of its employees and their spouses (the “OPEB Plans”). During the three months ended April 4, 2020, the Company closed its metal coil coating facility in Ambridge, Pennsylvania. The benefit plan associated with the Ambridge facility was frozen prior to the Company's acquisition of CENTRIA in fiscal 2015. In addition to the CENTRIA Benefit Plans, CENTRIA contributes to a multi-employer plan, the Steelworkers Pension Trust. The minimum required annual contribution to this plan is $0.3 million. The current contract expires on June 1, 2022. If we were to withdraw our participation from this multi-employer plan, CENTRIA may be required to pay a withdrawal liability representing an amount based on the underfunded status of the plan. The plan is not significant to the Company’s consolidated financial statements. Ply Gem Pension Plans — As a result of the Merger on November 16, 2018, we assumed the Ply Gem Group Pension Plan (the “Ply Gem Plan”) and the MW Manufacturers, Inc Retirement Plan (the “MW Plan”). The Ply Gem Plan was frozen during 1998, and no further increases in benefits for participants may occur as a result of increases in service years or compensation. The MW Plan was frozen for salaried participants during 2004 and non-salaried participants during 2005. No additional participants may enter the plan, but increases in benefits for participants as a result of increase in service years or compensation will occur. We refer to the RCC Pension Plan, the CENTRIA Benefit Plans, the Ply Gem Plan and the MW Plan collectively as the “Defined Benefit Plans” in this Note. The following tables set forth the components of the net periodic benefit cost, before tax for the periods indicated (in thousands): Defined Benefit Plans Three Months Ended Nine Months Ended October 3, September 28, October 3, September 28, Service cost $ 11 $ 11 $ 34 $ 32 Interest cost 802 974 2,405 2,922 Expected return on assets (1,398) (1,234) (4,193) (3,701) Amortization of prior service cost 16 15 47 43 Amortization of net actuarial loss 753 704 2,256 2,112 Net periodic benefit cost $ 184 $ 470 $ 549 $ 1,408 OPEB Plans Three Months Ended Nine Months Ended October 3, September 28, October 3, September 28, Service cost $ 4 $ 6 $ 13 $ 17 Interest cost 59 66 178 197 Amortization of net actuarial loss 27 — 81 — Net periodic benefit cost $ 90 $ 72 $ 272 $ 214 We expect to contribute $4.4 million to the Defined Benefit Plans and $0.8 million to OPEB Plans in the year ending December 31, 2020. Our policy is to fund the CENTRIA Benefit Plans as required by minimum funding standards of the Internal Revenue Code. The contributions to the OPEB Plans by retirees vary from none to 25% of the total premiums paid.

LONG-TERM DEBT

LONG-TERM DEBT	9 Months Ended
	Oct. 03, 2020
Debt Disclosure [Abstract]
LONG-TERM DEBT	LONG-TERM DEBT Debt is comprised of the following (in thousands): October 3, December 31, Asset-based revolving credit facility due April 2023 $ — $ 70,000 Term loan facility due April 2025 2,504,372 2,523,587 Cash flow revolver due April 2023 — — 8.00% senior notes due April 2026 645,000 645,000 6.125% senior notes due January 2029 500,000 — Less: unamortized discounts and unamortized deferred financing costs (1) (56,470) (56,063) Total long-term debt, net of unamortized discounts and unamortized deferred financing costs 3,592,902 3,182,524 Less: current portion of long-term debt 25,600 25,600 Total long-term debt, less current portion $ 3,567,302 $ 3,156,924 (1) Includes the unamortized discounts associated with the term loan facility and 8.00 % senior notes due April 2026, and the unamortized deferred financing costs associated with the term loan facility and 6.125% senior notes due January 2029. The unamortized deferred financing costs associated with the asset-based revolving credit facilities of $1.9 million and $2.4 million as of October 3, 2020 and December 31, 2019, respectively, are classified in other assets on the consolidated balance sheets. Term Loan Facility due April 2025 and Cash Flow Revolver due April 2023 On April 12, 2018, Ply Gem Midco entered into the Current Cash Flow Credit Agreement, which provides for (i) a term loan facility (the “Current Term Loan Facility”) in an original aggregate principal amount of $1,755.0 million, issued with a discount of 0.5%, and (ii) a cash flow-based revolving credit facility (the “Current Cash Flow Revolver” and together with the Term Loan Facility, the “Current Cash Flow Facilities”) of up to $115.0 million. The Current Term Loan Facility amortizes in nominal quarterly installments equal to one percent of the aggregate initial principal amount thereof per annum, with the remaining balance payable upon final maturity of the Current Term Loan Facility on April 12, 2025. There are no amortization payments under the Current Cash Flow Revolver, and all borrowings under the Current Cash Flow Revolver mature on April 12, 2023. On November 16, 2018, the Company entered into an incremental term loan facility in connection with the Merger, which increased the aggregate principal amount of the Current Term Loan Facility by $805.0 million. The proceeds of this incremental term loan facility were used to, among other things, (a) finance the Merger and to pay certain fees, premiums and expenses incurred in connection therewith, (b) repay in full amounts outstanding under the Pre-merger Term Loan Credit Agreement and the Pre-merger ABL Credit Agreement and (c) repay $325.0 million of borrowings outstanding under the ABL Facility. On November 16, 2018, in connection with the consummation of the Merger, NCI and Ply Gem Midco entered into a joinder agreement with respect to the Current Cash Flow Facilities, and the Company became the Borrower (as defined in the Current Cash Flow Credit Agreement) under the Current Cash Flow Facilities. The Current Term Loan Facility bears annual interest at a floating rate measured by reference to, at the Company’s option, either (i) an adjusted LIBOR rate (subject to a floor of 0.00%) plus an applicable margin of 3.75% per annum or (ii) an alternate base rate plus an applicable margin of 2.75% per annum. At October 3, 2020, the interest rates on the Current Term Loan Facility were as follows: October 3, 2020 Interest rate 3.9 % Effective interest rate 6.51 % The Company entered into certain interest rate swap agreements during 2019 to convert a portion of its variable rate debt to fixed. See Note 17 - Fair Value of Financial Instruments and Fair Value Measurements . Loans outstanding under the Current Cash Flow Revolver bear annual interest at a floating rate measured by reference to, at the Company’s option, either (i) an adjusted LIBOR rate (subject to a floor of 0.00%) plus an applicable margin ranging from 2.50% to 3.00% per annum depending on the Company’s secured leverage ratio or (ii) an alternate base rate plus an applicable margin ranging from 1.50% to 2.00% per annum depending on the Company’s secured leverage ratio. Additionally, unused commitments under the Current Cash Flow Revolver are subject to a fee ranging from 0.25% to 0.50% per annum depending on the Company’s secured leverage ratio. At October 3, 2020, the weighted average interest rate on the Current Cash Flow Revolver was 3.31%. The Current Term Loan Facility and Current Cash Flow Revolver may be prepaid at the Company’s option at any time without premium or penalty (other than customary breakage costs), subject to minimum principal amount requirements. Subject to certain exceptions, the Current Term Loan Facility is subject to mandatory prepayments in an amount equal to: • the net cash proceeds of (1) certain asset sales, (2) certain debt offerings and (3) certain insurance recovery and condemnation events; and • 50% of annual excess cash flow (as defined in the Cash Flow Credit Agreement), subject to reduction to 25% and 0% if specified secured leverage ratio targets are met to the extent that the amount of such excess cash flow exceeds $10.0 million. For 2019, no payments were required under the excess cash flow calculation. The obligations under the Current Cash Flow Credit Agreement are guaranteed by each direct and indirect wholly-owned U.S. restricted subsidiary of the Company, subject to certain exceptions, and are secured by: • a perfected security interest in substantially all tangible and intangible assets of the Company and each subsidiary guarantor (other than ABL Priority Collateral (as defined below)), including the capital stock of each direct material wholly-owned U.S. restricted subsidiary owned by the Company and each subsidiary guarantor, and 65% of the capital stock of any non-U.S. subsidiary held directly by the Company or any subsidiary guarantor, subject to certain exceptions (the “Cash Flow Priority Collateral”), which security interest will be senior to the security interest in the foregoing assets securing the Current ABL Facility; and • a perfected security interest in the ABL Priority Collateral, which security interest will be junior to the security interest in the ABL Priority Collateral securing the Current ABL Facility. The Current Cash Flow Revolver includes a financial covenant set at a maximum secured leverage ratio of 7.75:1.00, which will apply if the outstanding amount of loans and drawings under letters of credit which have not then been reimbursed exceeds a specified threshold at the end of any fiscal quarter. ABL Facility due April 2023 On April 12, 2018, Ply Gem Midco entered into the Current ABL Credit Agreement, which provides for an asset-based revolving credit facility (the “Current ABL Facility”) of up to $360.0 million, consisting of (i) $285.0 million available to U.S. borrowers (subject to U.S. borrowing base availability) (the “ABL U.S. Facility”) and (ii) $75.0 million available to both U.S. borrowers and Canadian borrowers (subject to U.S. borrowing base and Canadian borrowing base availability) (the “ABL Canadian Facility”). The Company and, at their option, certain of their subsidiaries are the borrowers under the Current ABL Facility. All borrowings under the Current ABL Facility mature on April 12, 2023. On October 15, 2018, Ply Gem Midco entered into an incremental asset-based revolving credit facility of $36.0 million, which upsized the Current ABL Facility to $396.0 million in the aggregate, and with (x) the ABL U.S. Facility being increased from $285.0 million to $313.5 million and (y) the ABL Canadian Facility being increased from $75.0 million to $82.5 million. On November 16, 2018, Ply Gem Midco entered into an incremental asset-based revolving credit facility of $215.0 million in connection with the Merger, which upsized the Current ABL Facility to $611.0 million in the aggregate, and with (x) the ABL U.S. Facility being increased from $313.5 million to approximately $483.7 million and (y) the ABL Canadian Facility being increased from $82.5 million to approximately $127.3 million. On November 16, 2018, in connection with the consummation of the Merger, the Company and Ply Gem Midco entered into a joinder agreement with respect to the Current ABL Facility, and the Company became the Parent Borrower (as defined in the ABL Credit Agreement) under the Current ABL Facility. Borrowing availability under the Current ABL Facility is determined by a monthly borrowing base collateral calculation that is based on specified percentages of the value of eligible inventory, eligible accounts receivable and eligible credit card receivables, less certain reserves and subject to certain other adjustments as set forth in the Current ABL Credit Agreement. Availability is reduced by issuance of letters of credit as well as any borrowings. As of October 3, 2020, the Company had the following in relation to the Current ABL Facility (in thousands): October 3, 2020 Excess availability $ 570,000 Revolving loans outstanding — Letters of credit outstanding 36,500 Loans outstanding under the Current ABL Facility bear interest at a floating rate measured by reference to, at the Company’s option, either (i) an adjusted LIBOR rate (subject to a LIBOR floor of 0.00%) plus an applicable margin ranging from 1.25% to 1.75% per annum depending on the average daily excess availability under the Current ABL Facility or (ii) an alternate base rate plus an applicable margin ranging from 0.25% to 0.75% per annum depending on the average daily excess availability under the ABL Facility. Additionally, unused commitments under the ABL Facility are subject to a 0.25% per annum fee. At October 3, 2020, the weighted average interest rate on the Current ABL Facility was 1.87% . The obligations under the Current ABL Credit Agreement are guaranteed by each direct and indirect wholly-owned U.S. restricted subsidiary of the Company, subject to certain exceptions, and are secured by: • a perfected security interest in all present and after-acquired inventory, accounts receivable, deposit accounts, securities accounts, and any cash or other assets in such accounts and other related assets owned by the Company and the U.S. subsidiary guarantors and the proceeds of any of the foregoing, except to the extent such proceeds constitute Cash Flow Priority Collateral, and subject to certain exceptions (the “ABL Priority Collateral”), which security interest is senior to the security interest in the foregoing assets securing the Current Cash Flow Facilities; and • a perfected security interest in the Cash Flow Priority Collateral, which security interest will be junior to the security interest in the Cash Flow Collateral securing the Current Cash Flow Facilities. Additionally, the obligations of the Canadian borrowers under the Current ABL Credit Agreement are guaranteed by each direct and indirect wholly-owned Canadian restricted subsidiary of the Canadian borrowers, subject to certain exceptions, and are secured by substantially all assets of the Canadian borrowers and the Canadian subsidiary guarantors, subject to certain exceptions. The Current ABL Credit Agreement includes a minimum fixed charge coverage ratio of 1.00:1.00, which is tested only when specified availability is less than 10.0% of the lesser of (x) the then applicable borrowing base and (y) the then aggregate effective commitments under the Current ABL Facility, and continuing until such time as specified availability has been in excess of such threshold for a period of 20 consecutive calendar days. 8.00% Senior Notes due April 2026 On April 12, 2018, Ply Gem Midco issued $645.0 million at a discount of 2.25% in aggregate principal amount of 8.00% Senior Notes due April 2026 (the “8.00% Senior Notes”). The 8.00% Senior Notes bear interest at 8.00% per annum and will mature on April 15, 2026. Interest is payable semi-annually in arrears on April 15 and October 15. The effective interest rate for the 8.00% Senior Notes was 8.64% as of October 3, 2020, after considering each of the different interest expense components of this instrument, including the coupon payment and the deferred debt issuance costs. On November 16, 2018, in connection with the consummation of the Merger, the Company entered into a supplemental indenture and assumed the obligations of Ply Gem Midco as issuer under the Current Indenture. The 8.00% Senior Notes are guaranteed on a senior unsecured basis by each of the Company’s wholly-owned domestic subsidiaries that guarantee the Company’s obligations under the Current Cash Flow Facilities or the Current ABL Facility (including by reason of being a borrower under the Current ABL Facility on a joint and several basis with the Company or a subsidiary guarantor). The 8.00% Senior Notes are unsecured senior indebtedness and rank equally in right of payment with the Current Cash Flow Facilities and Current ABL Facility. The 8.00% Senior Notes are effectively subordinated to all of the Company’s secured debt, including the Current Cash Flow Facilities and Current ABL Facility, and are senior in right of payment to all subordinated obligations of the Company. The Company may redeem the 8.00% Senior Notes in whole or in part at any time as set forth below: • prior to April 15, 2021, the Company may redeem the 8.00% Senior Notes at a price equal to 100% of the principal amount thereof, plus accrued and unpaid interest, if any, to but not including the redemption date, plus the applicable make-whole premium; • prior to April 15, 2021, the Company may redeem up to 40.0% of the original aggregate principal amount of the 8.00% Senior Notes with proceeds of certain equity offerings, at a redemption price of 108%, plus accrued and unpaid interest, if any, to but not including the redemption date; and • on or after April 15, 2021, the Company may redeem the 8.00% Senior Notes at specified redemption prices starting at 104% and declining ratably to 100.0% by April 15, 2023, plus accrued and unpaid interest, if any, to but not including the redemption date. 6.125% Senior Notes due January 2029 On September 24, 2020, the Company issued $500.0 million in aggregate principal amount of 6.125% Senior Notes due January 2029 ("the 6.125% Senior Notes"). Proceeds from the 6.125% Senior Notes were used to repay outstanding amounts under the Company's Current ABL Facility and Current Cash Flow Revolver. The 6.125% Senior Notes bear interest at 6.125% per annum and will mature on January 15, 2029. Interest is payable semi-annually in arrears on January 15 and July 15 commencing on January 15, 2021. The 6.125% Senior Notes are guaranteed on a senior unsecured basis by each of the Company’s existing and future wholly-owned domestic subsidiaries that guarantee the Company’s obligations under the Current Cash Flow Facilities or the Current ABL Facility (including by reason of being a borrower under the Current ABL Facility on a joint and several basis with the Company or a subsidiary guarantor). The 6.125% Senior Notes are unsecured senior indebtedness and are effectively subordinated to all of the Company’s existing and future senior secured indebtedness, including indebtedness under the Company’s Term Loan Facility, Current Cash Flow Revolver and Current ABL Facility, and are senior in right of payment to future subordinated indebtedness of the Company. The Company may redeem the 6.125% Senior Notes in whole or in part at any time as set forth below: • prior to September 15, 2023, at a price equal to 100% of the principal amount thereof, plus accrued and unpaid interest, if any, to but not including the redemption date, plus the applicable make-whole premium; • prior to September 15, 2023, up to 40% of the aggregate principal amount with the proceeds of certain equity offerings at a redemption price of 106.125% plus accrued and unpaid interest, if any, to but not including the redemption date; • on or after September 15, 2023 and prior to September 15, 2024, at a price equal to 103.063% of the principal amount thereof, plus accrued and unpaid interest, if any, to but not including the redemption date; • on or after September 15, 2024 and prior to September 15, 2025, at a price equal to 101.531% of the principal amount thereof, plus accrued and unpaid interest, if any, to but not including the redemption date; and • on or after September 15, 2025, at a price equal to 100.000% of the principal amount thereof, plus accrued and unpaid interest, if any, to but not including the redemption date. Debt Covenants The Company’s debt agreements contain a number of covenants that, among other things, limit or restrict the ability of the Company and its subsidiaries to incur additional indebtedness; make dividends and other restricted payments; incur additional liens; consolidate, merge, sell or otherwise dispose of all or substantially all assets; make investments; transfer or sell assets; enter into restrictive agreements; change the nature of the business; and enter into certain transactions with affiliates. As of October 3, 2020, the Company was in compliance with all covenants that were in effect on such date.

CD&R INVESTOR GROUP

CD&R INVESTOR GROUP	9 Months Ended
	Oct. 03, 2020
Equity [Abstract]
CD&R Investor Group	CD&R INVESTOR GROUP On August 14, 2009, the Company entered into an Investment Agreement (as amended, the “Investment Agreement”), by and between the Company and Clayton, Dubilier & Rice Fund VIII, L.P., a Cayman Islands exempted limited partnership (“CD&R Fund VIII”). In connection with the Investment Agreement and the Stockholders Agreement dated October 20, 2009 (the “Old Stockholders Agreement”), CD&R Fund VIII and CD&R Friends & Family Fund VIII, L.P., a Cayman Islands exempted limited partnership (“CD&R FF Fund” and, together with CD&R Fund VIII, the “CD&R Fund VIII Investor Group”) purchased convertible preferred stock of the Company, which was converted into shares of our common stock on May 14, 2013. Ply Gem Holdings was acquired by CD&R Fund X and Atrium Intermediate Holdings, LLC, GGC BP Holdings, LLC and AIC Finance Partnership, L.P. (collectively, the “Golden Gate Investor Group”) and merged with Atrium on April 12, 2018 (the “Ply Gem-Atrium Merger”). Pursuant to the terms of the Merger Agreement, on November 16, 2018, the Company entered into (i) a stockholders agreement (the “New Stockholders Agreement”) between the Company, and each of the CD&R Fund VIII Investor Group, CD&R Pisces Holdings, L.P., a Cayman Islands exempted limited partnership (“CD&R Pisces”, and together with the CD&R Fund VIII Investor Group, the “CD&R Investor Group”) and the Golden Gate Investor Group (together with the CD&R Investor Group, the “Investors”), pursuant to which the Company granted to the Investors certain governance, preemptive and subscription rights and (ii) a registration rights agreement (the “New Registration Rights Agreement”) between the Company and each of the Investors, pursuant to which the Company granted the Investors customary demand and piggyback registration rights, including rights to demand registrations and underwritten shelf registration statement offerings with respect to the shares of the Company’s Common Stock that are held by the Investors following the consummation of the Merger. On August 25, 2020, the Company filed a shelf registration statement on Form S-3, declared effective by the SEC on September 2, 2020, registering the resale of shares of the Company’s Common Stock held by CD&R Pisces. The Company had previously registered the resale of shares of the Company’s Common Stock held by the CD&R Fund VIII Investor Group and the Golden Gate Investor Group. Pursuant to the terms of the New Stockholders Agreement, the Company and the CD&R Fund VIII Investor Group terminated the Old Stockholders Agreement. Pursuant to the terms of the New Registration Rights Agreement, the Company and the CD&R Fund VIII Investor Group terminated the Registration Rights Agreement, dated as of October 20, 2009 (the “Old Registration Rights Agreement”), by and among the Company and the CD&R Fund VIII Investor Group. As of October 3, 2020 and December 31, 2019, the CD&R Investor Group owned approximately 49.5% and 49.1% of the outstanding shares of the Company’s Common Stock, respectively.

STOCK REPURCHASE PROGRAM

STOCK REPURCHASE PROGRAM	9 Months Ended
	Oct. 03, 2020
Equity [Abstract]
STOCK REPURCHASE PROGRAM	STOCK REPURCHASE PROGRAM On October 10, 2017 and March 7, 2018, the Company announced that its Board of Directors authorized new stock repurchase programs for the repurchase of up to an aggregate of $50.0 million and an additional $50.0 million, respectively, of the Company’s outstanding Common Stock for a cumulative total of $100.0 million. Under these repurchase programs, the Company is authorized to repurchase shares, if at all, at times and in amounts that it deems appropriate in accordance with all applicable securities laws and regulations. Shares repurchased pursuant to the repurchase programs are usually retired. There is no time limit on the duration of the programs. During the nine months ended October 3, 2020, the Company repurchased 1.1 million shares for $6.4 million under the stock repurchase programs. There were no stock repurchases under the stock repurchase programs during the nine months ended September 28, 2019. As of October 3, 2020, $49.1 million remained available for stock repurchases under the program announced on March 7, 2018. The timing and method of any repurchases, which will depend on a variety of factors, including market conditions, are subject to results of operations, financial conditions, cash requirements and other factors, and may be suspended or discontinued at any time.

FAIR VALUE OF FINANCIAL INSTRUM

FAIR VALUE OF FINANCIAL INSTRUMENTS AND FAIR VALUE MEASUREMENTS	9 Months Ended
	Oct. 03, 2020
Fair Value Disclosures [Abstract]
FAIR VALUE OF FINANCIAL INSTRUMENTS AND FAIR VALUE MEASUREMENTS	FAIR VALUE OF FINANCIAL INSTRUMENTS AND FAIR VALUE MEASUREMENTS Fair Value of Financial Instruments The carrying amounts of cash and cash equivalents, restricted cash, trade accounts receivable, accounts payable and notes payable approximate fair value as of October 3, 2020 and December 31, 2019, respectively, because of their relatively short maturities. The carrying amounts of the indebtedness under the Current ABL Facility and Current Cash Flow Revolver approximate fair value as the interest rates are variable and reflective of market rates. At October 3, 2020, there wer e no borrowings outstanding under the Current ABL Facility and the Current Cash Flow Revolver. The fair values of the remaining financial instruments not currently recognized at fair value on our consolidated balance sheets at the respective period ends were (in thousands): October 3, 2020 December 31, 2019 Carrying Fair Value Carrying Fair Value Term Loan Facility $ 2,504,372 $ 2,479,328 $ 2,523,587 $ 2,514,906 8.00% Senior Notes 645,000 675,638 645,000 670,800 6.125% Senior Notes 500,000 505,000 — — The fair value of the term loan facility was based on recent trading activities of comparable market instruments, which are level 2 inputs and the fair values of the 8.00% and 6.125% senior notes were based on quoted prices in active markets for the identical liabilities, which are level 1 inputs. Fair Value Measurements ASC Subtopic 820-10, Fair Value Measurements and Disclosures , requires us to use valuation techniques to measure fair value that maximize the use of observable inputs and minimize the use of unobservable inputs. These inputs are prioritized as follows: Level 1 : Observable inputs such as quoted prices for identical assets or liabilities in active markets. Level 2 : Other inputs that are observable directly or indirectly, such as quoted prices for similar assets or liabilities or market-corroborated inputs. Level 3 : Unobservable inputs for which there is little or no market data and which require us to develop our own assumptions about how market participants would price the assets or liabilities. The following is a description of the valuation methodologies used for assets and liabilities measured at fair value. There have been no changes in the methodologies used as of October 3, 2020 and December 31, 2019. Money market: Money market funds have original maturities of three months or less. The original cost of these assets approximates fair value due to their short-term maturity. Mutual funds: Mutual funds are valued at the closing price reported in the active market in which the mutual fund is traded. Assets held for sale: Assets held for sale are valued based on current market conditions, prices of similar assets in similar condition and expected proceeds from the sale of the assets, representative of Level 3 inputs. Deferred compensation plan liability: Deferred compensation plan liability is comprised of phantom investments in the deferred compensation plan and is valued at the closing price reported in the active markets in which the money market and mutual funds are traded. Interest rate swap liability: Interest rate swap liabilities are based on cash flow hedge contracts that have fixed rate structures and are measured against market-based LIBOR yield curves. These interest rate swaps were classified within Level 2 of the fair value hierarchy because they were valued using alternative pricing sources or models that utilized market observable inputs, including current and forward interest rates. The following tables summarize information regarding our financial assets and liabilities that are measured at fair value on a recurring basis as of October 3, 2020 and December 31, 2019, segregated by the level of the valuation inputs within the fair value hierarchy utilized to measure fair value (in thousands): October 3, 2020 Level 1 Level 2 Level 3 Total Assets: Short-term investments in deferred compensation plan (1) : Money market $ 197 $ — $ — $ 197 Mutual funds – Growth 397 — — 397 Mutual funds – Blend 890 — — 890 Mutual funds – Foreign blend 282 — — 282 Mutual funds – Fixed income — 151 — 151 Total short-term investments in deferred compensation plan (2) 1,766 151 — 1,917 Total assets $ 1,766 $ 151 $ — $ 1,917 Liabilities: Deferred compensation plan liability (2) $ — $ 2,154 $ — $ 2,154 Interest rate swap liability (3) — 83,304 — 83,304 Total liabilities $ — $ 85,458 $ — $ 85,458 December 31, 2019 Level 1 Level 2 Level 3 Total Assets: Short-term investments in deferred compensation plan (1) : Money market $ 2 $ — $ — $ 2 Mutual funds – Growth 1,044 — — 1,044 Mutual funds – Blend 1,769 — — 1,769 Mutual funds – Foreign blend 572 — — 572 Mutual funds – Fixed income — 389 — 389 Total short-term investments in deferred compensation plan (2) 3,387 389 — 3,776 Total assets $ 3,387 $ 389 $ — $ 3,776 Liabilities: Deferred compensation plan liability (2) $ — $ 3,847 $ — $ 3,847 Interest rate swap liability (3) — 29,988 — 29,988 Total liabilities $ — $ 33,835 $ — $ 33,835 (1) Unrealized holding losses for the three months ended September 28, 2019 were $0.1 million. Unrealized holding gains (losses) for the nine months ended October 3, 2020 and September 28, 2019 were $(0.7) million and $0.4 million, respectively. These unrealized holding gains (losses) were substantially offset by changes in the deferred compensation plan liability. (2) The Company records the short-term investments in deferred compensation plan within investments in debt and equity securities, at market, and the deferred compensation plan liability within accrued compensation and benefits on the consolidated balance sheets. (3) In May 2019, the Company entered into four-year interest rate swaps to mitigate variability in forecasted interest payments on $1,500.0 million of the Company’s term loan secured variable debt. The interest rate swaps effectively convert a portion of the floating rate interest payments into a fixed rate interest payment. There are three interest rate swaps that cover $500.0

INCOME TAXES

INCOME TAXES	9 Months Ended
	Oct. 03, 2020
Income Tax Disclosure [Abstract]
INCOME TAXES	INCOME TAXES Under FASB ASC 740-270, Income Taxes - Interim Reporting , each interim period is considered an integral part of the annual period and tax expense is measured using an estimated annual effective tax rate. Estimates of the annual effective tax rate at the end of interim periods are, of necessity, based on evaluation of possible future events and transactions and may be subject to subsequent refinement or revision. The Company calculates its quarterly tax provision consistent with the guidance provided by ASC 740-270, whereby the Company forecasts its estimated annual effective tax rate then applies that rate to its year-to-date ordinary pre-tax book income (loss). In addition, the Company excludes jurisdictions with a projected loss for the year or the year-to-date ordinary loss where the Company cannot recognize a tax benefit from its estimated annual effective tax rate. The impact of such an exclusion could result in a higher or lower effective tax rate during a particular quarter, based upon the mix and timing of actual earnings versus annual projections. In addition to the tax resulting from applying the estimated annual effective tax rate to pre-tax income (loss), the Company includes certain items treated as discrete events to arrive at an estimated effective tax rate. Future changes in the forecasted annual income (loss) projections, tax rate changes, or discrete tax items could result in significant adjustments to quarterly income tax expense in future periods in accordance with ASC 740-270. For the nine months ended October 3, 2020, the Company's estimated annual effective income tax of ordinary forecasted book income excluding the goodwill impairment was approximately 40.0%, which varied from the statutory rate primarily due to state income tax expense, valuation allowances, and foreign income taxes. For the nine months ended October 3, 2020, the effective tax rate was 2.5%, which varied from the annual effective tax rate due to the following discrete items recorded during the period: unrecognized tax benefits, adjustments to state income tax rates, and goodwill impairment. Valuation allowance As of October 3, 2020, the Company remains in a valuation allowance position, in the amount of $11.3 million, against its deferred tax assets for certain state jurisdictions for certain entities as it is currently deemed “ more likely than not ” that the benefit of such net tax assets will not be utilized as the Company continues to be in a three-year cumulative loss position for these state jurisdictions. The Company will continue to monitor the positive and negative factors for these jurisdictions and make further changes to the valuation allowances as necessary. Unrecognized tax benefits Despite the Company’s belief that its tax return positions are consistent with applicable tax laws, the Company believes that certain positions could be challenged by taxing authorities. The Company’s tax reserves reflect the difference between the tax benefit claimed on tax returns and the amount recognized in the consolidated financial statements. These reserves have been established based on management’s assessment as to potential exposure attributable to permanent differences and interest and penalties applicable to both permanent and temporary differences. The tax reserves are reviewed periodically and adjusted in light of changing facts and circumstances, such as progress of tax audits, lapse of applicable statutes of limitations and changes in tax law. The Company is currently under examination by various taxing authorities. During the nine months ended October 3, 2020, the tax reserves increased by approximately $0.6 million. The increase is primarily due to additional interest expense related to previously recorded unrecognized tax benefits. The liability for unrecognized tax benefits as of October 3, 2020 was approximately $12.5 million and is recorded in other long-term liabilities in the accompanying consolidated balance sheet. CARES Act In response to the COVID-19 pandemic, the Coronavirus Aid, Relief and Economic Security Act ("CARES Act") was signed into law on March 27, 2020. The CARES Act, among other things, includes tax provisions relating to refundable payroll tax credits, deferment of employer side social security payments, net operating loss utilization and carryback periods, modifications to the net interest deduction limitations and technical corrections to tax depreciation methods for qualified improvement property (QIP). Specifically, the CARES Act amends IRC §163(j) for tax years 2019 and 2020. The CARES Act increases the 30% adjusted taxable income threshold to 50% and allows taxpayers to elect to use their 2019 adjusted taxable income as their adjusted taxable income in the 2020 §163(j) calculation. The combination of these two factors will allow the Company to deduct additional interest expense for income tax purposes that would have been previously disallowed. The Company continues to evaluate the impact of the CARES Act on our financial position, results of operations, and cash flows. During July 2020, the Department of Treasury issued several Final and Proposed Regulations related to the Tax Cuts and Jobs Act, including those related to the §250 deduction, global intangible low-taxed income (“GILTI”) and the §163(j) interest limitation. We are evaluating the impact of the Regulations on our income tax balances.

SEGMENT INFORMATION

SEGMENT INFORMATION	9 Months Ended
	Oct. 03, 2020
Segment Reporting [Abstract]
SEGMENT INFORMATION	SEGMENT INFORMATION Operating segments are defined as components of an enterprise that engage in business activities for which discrete financial information is available and is evaluated on a regular basis by the chief operating decision maker to make decisions regarding the allocation of resources to the segment and assess the performance of the segment. The Company has three reportable segments: Windows, Siding and Commercial. These operating segments follow the same accounting policies used for our consolidated financial statements. We evaluate a segment’s performance based primarily upon operating income before corporate expenses. Corporate assets consist primarily of cash, investments, prepaid expenses, current and deferred taxes and property, plant and equipment associated with our headquarters in Cary, North Carolina and office in Houston, Texas. These items (and income and expenses related to these items) are not allocated to the operating segments. Corporate unallocated expenses include share-based compensation expenses, restructuring charges, acquisition costs, and other expenses related to executive, legal, finance, tax, treasury, human resources, information technology and strategic sourcing, and corporate travel expenses. Additional unallocated amounts primarily include non-operating items such as interest income, interest expense and other income (expense). The following table represents summary financial data attributable to the segments for the periods indicated (in thousands): Three Months Ended Nine Months Ended October 3, September 28, October 3, September 28, Net sales: Windows $ 501,314 $ 504,338 $ 1,378,039 $ 1,434,579 Siding 321,898 315,799 848,190 840,601 Commercial 404,041 464,906 1,199,771 1,370,152 Total net sales $ 1,227,253 $ 1,285,043 $ 3,426,000 $ 3,645,332 Operating income (loss): Windows $ 37,295 $ 34,446 $ (252,794) $ 62,039 Siding 45,313 37,063 (92,916) 51,346 Commercial 56,137 59,317 109,642 142,436 Corporate (34,766) (35,266) (101,819) (106,695) Total operating income (loss) 103,979 95,560 (337,887) 149,126 Unallocated other expense, net (50,402) (56,293) (159,056) (170,894) Income (loss) before taxes $ 53,577 $ 39,267 $ (496,943) $ (21,768) October 3, December 31, Total assets: Windows $ 1,820,255 $ 2,166,220 Siding 2,158,395 2,289,310 Commercial 878,623 963,291 Corporate 617,708 145,525 Total assets $ 5,474,981 $ 5,564,346

CONTINGENCIES

CONTINGENCIES	9 Months Ended
	Oct. 03, 2020
Commitments and Contingencies Disclosure [Abstract]
CONTINGENCIES	CONTINGENCIES As a manufacturer of products primarily for use in building construction, the Company is inherently exposed to various types of contingent claims, both asserted and unasserted, in the ordinary course of business. As a result, from time to time, the Company and/or its subsidiaries become involved in various legal proceedings or other contingent matters arising from claims or potential claims. The Company insures against these risks to the extent deemed prudent by its management and to the extent insurance is available. Many of these insurance policies contain deductibles or self-insured retentions in amounts the Company deems prudent and for which the Company is responsible for payment. In determining the amount of self-insurance, it is the Company’s policy to self-insure those losses that are predictable, measurable and recurring in nature. The Company regularly reviews the status of ongoing proceedings and other contingent matters along with legal counsel. Liabilities for such items 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 ultimate disposition of these matters will not have a material adverse effect on the Company’s results of operations, financial position or cash flows. However, such matters are subject to many uncertainties and outcomes are not predictable with assurance. Environmental The Company's operations are subject to various federal, state, local and foreign environmental, health and safety laws. Among other things, these laws regulate the emissions or discharge of materials into the environment; govern the use, storage, treatment, disposal and management of hazardous substances and wastes; protect the health and safety of our employees and the end-users of our products; regulate the materials used to manufacture our products; and impose liability for the costs of investigating and remediating present and past releases of hazardous substances. Violations of these laws or of any conditions contained in Company environmental permits can result in substantial fines or corrective consent orders, injunctive relief, requirements to install pollution control or other environmental-related equipment, and civil sanctions. We could be held liable for costs to investigate, remediate or otherwise address contamination at any real property we have ever owned, operated or used as a disposal site, or at other sites where we or predecessors may have released hazardous materials. We could incur fines, penalties or sanctions or be subject to third-party claims, including indemnification claims, for property damage, personal injury or otherwise as a result of violations of (or liabilities under) environmental, health and safety laws, or in connection with releases of hazardous materials. One of the Company’s subsidiaries entered into an Administrative Order on Consent (the “Consent Order”) with the United States Environmental Protection Agency ("EPA"), under the Resource Conservation and Recovery Act ("RCRA") Corrective Action Program, in September 2011 to address known releases of hazardous substances at its Rocky Mount, Virginia facility. A Phase I RCRA Facility Investigation ("RFI") was submitted to the Virginia Department of Environmental Quality ("VDEQ") in December 2015, and a Phase II RFI and Human Health Risk Assessment and Baseline Ecological Risk Assessment were submitted in October 2018. A Limited Corrective Measures Study ("LCM") based on these investigations was approved by the VDEQ in January 2020. Current estimates of remaining costs for predicted assessment, remediation and monitoring activities as of October 3, 2020 are $4.5 million. The Company has recorded approximately $1.0 million of this environmental liability within current liabilities at October 3, 2020 and approximately $3.5 million within other long-term liabilities in the Company’s consolidated balance sheets at October 3, 2020. The EPA is investigating groundwater contamination at a Superfund site in York, Nebraska referred to as the PCE/TCE Northeast Contamination Site (“PCE/TCE Site"). A subsidiary of the Company has been named a potentially responsible party (“PRP”) with respect to the PCE/TCE Site and has liability for investigation and remediation costs associated with the contamination. In May 2019, the subsidiary and an unrelated respondent entered into an Administrative Settlement Agreement and Order on Consent with the EPA to conduct a Remedial Investigation/Feasibility Study ("RI/FS") of the PCE/TCE Site. A final RI/FS Work Plan was submitted to the EPA in November 2019 and approved in December 2019. RI Phase I field work began in February 2020 but was paused in March 2020 due to the COVID-19 pandemic. The Company has recorded a liability of $4.6 million within other long-term liabilities in its consolidated balance sheets as of October 3, 2020. We will adjust our remediation liability in future periods, if necessary, as the RI/FS progresses or if additional requirements are imposed. We may be able to recover a portion of costs incurred in connection with the PCE/TCE Site from other responsible parties, although there are no assurances that we will receive any funds. Based on current information, the Company is not aware of any environmental compliance obligations, claims or investigations that will have a material adverse effect on its results of operations, cash flows or financial position except as otherwise disclosed in the Company’s consolidated financial statements. However, there can be no guarantee that previously known or newly discovered matters will not result in material costs or liabilities. Litigation The Company believes it has valid defenses to the outstanding claims discussed below and will vigorously defend all such claims; however, litigation is subject to many uncertainties and there cannot be any assurance that the Company will ultimately prevail or, in the event of an unfavorable outcome or settlement of litigation, that the ultimate liability would not be material and would not have a material adverse effect on the business, results of operations, cash flows or financial position of the Company. In November 2018, Aurora Plastics, LLC (“Aurora”) initiated an arbitration demand against Atrium Windows and Doors, Inc., Atrium Extrusion Systems, Inc., and North Star Manufacturing (London) Ltd. (collectively, “Atrium”) pursuant to a Third Amended and Restated Vinyl Compound and Supply Agreement dated as of December 22, 2016. A settlement was reached in this case during the fourth quarter of 2019. The Company has a $7.6 million liability as of October 3, 2020 related to this settlement, of which $3.6 million is held within other current liabilities with the remaining in long-term liabilities in the consolidated balance sheets. On November 14, 2018, an individual stockholder, Gary D. Voigt, filed a putative class action Complaint in the Delaware Court of Chancery against Clayton Dubilier & Rice, LLC (“CD&R”), Clayton, Dubilier & Rice Fund VIII, L.P. (“CD&R Fund VIII”), and certain directors of the Company. Voigt purports to assert claims on behalf of himself, on behalf of a class of other similarly situated stockholders of the Company, and derivatively on behalf of the Company, the nominal defendant. An Amended Complaint was filed on April 11, 2019. The Amended Complaint asserts claims for breach of fiduciary duty and unjust enrichment against CD&R Fund VIII and CD&R, and for breach of fiduciary duty against twelve director defendants in connection with the Merger. Defendants moved to dismiss the Amended Complaint and, on February 10, 2020, the court denied the motions except as to four of the director defendants. Voigt seeks damages in an amount to be determined at trial. Other contingencies The Company’s imports of fabricated structural steel (“FSS”) from its Mexican affiliate, Building Systems de Mexico S.A. de C.V. (“BSM”) were subject to antidumping (“AD”) and countervailing duty (“CVD”) tariff proceedings before the U.S. Department of Commerce (“DOC”) and the U.S. International Trade Commission (“USITC”). The proceedings were initiated in February 2019 by the American Institute of Steel Construction against FSS being imported into the USA from Mexico, Canada, and China. In 2019, the DOC issued preliminary tariff rates and in 2020 finalized CVD and AD tariff rates of 0% and 8.47%, respectively, for the Company’s imports of FSS from BSM. However, in February 2020, in a 3 to 2 vote, the USITC concluded there was no injury or threat of injury to the domestic FSS industry. In March 2020 the USITC opinion was published in the Federal Register, ceasing the Company's requirement to pay the AD and CVD tariffs. The Company has received full reimbursement for the $4.1 million in tariffs previously deposited with United States Customs and Border Protection and recorded a reduction in costs of sales during the three months ended October 3, 2020. This matter has been appealed and the Company will continue to vigorously advocate its position that its import of FSS from BSM should not be subject to any CVD or AD tariffs. The Company is subject to other contingencies, including legal proceedings and claims arising out of its operations and businesses that cover a wide range of matters, including, among others, environmental, contract, employment, intellectual property, securities, personal injury, property damage, product liability, warranty, and modification, adjustment or replacement of component parts or units sold, which may include product recalls. Product liability, environmental and other legal proceedings also include matters with respect to businesses previously owned. The Company has used various substances in products and manufacturing operations, which have been or may be deemed to be hazardous or dangerous, and the extent of its potential liability, if any, under environmental, product liability and workers’ compensation statutes, rules, regulations and case law is unclear. Further, due to the lack of adequate information and the potential impact of present regulations and any future regulations, there are certain circumstances in which no range of potential exposure may be reasonably estimated. Also, it is not possible to ascertain the ultimate legal and financial liability with respect to certain contingent liabilities, including lawsuits, and therefore no such estimate has been made as of October 3, 2020.

SUMMARY OF SIGNIFICANT ACCOUN_2

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies)	9 Months Ended
	Oct. 03, 2020
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The accompanying unaudited consolidated financial statements for Cornerstone Building Brands, Inc. (together with its subsidiaries, unless otherwise indicated, the “Company,” “Cornerstone,” “NCI”, “we,” “us” or “our”) have been prepared in accordance with generally accepted accounting principles for interim financial information and with the instructions to Form 10-Q and Article 10 of Regulation S-X. Accordingly, they do not include all of the information and notes required by generally accepted accounting principles (“GAAP”) for complete financial statements. In the opinion of management, the unaudited consolidated financial statements included herein contain all adjustments, which consist of normal recurring adjustments, necessary to fairly present the Company’s financial position, results of operations and cash flows for the periods indicated. Operating results for the period from January 1, 2020 through October 3, 2020 are not necessarily indicative of the results that may be expected for the fiscal year ending December 31, 2020. Certain reclassifications have been made to the prior period disaggregated revenue amounts in the notes to the consolidated financial statements to conform to the current presentation. The net effect of these reclassifications was not material to the consolidated financial statements (see disaggregated revenue table below).
Reporting Periods	Reporting Periods The Company’s current fiscal quarters are based on a four-four-five week calendar with periods ending on the Saturday of the last week in the quarter except that December 31st will always be the year-end date. Therefore, the financial results of certain fiscal quarters may not be comparable to prior fiscal quarters.
Accounts Receivables and Related Allowance	Accounts Receivables and Related Allowance The Company reports accounts receivable net of the allowance for expected credit losses. Trade accounts receivable are the result of sales of metal building products, insulated metal panels, metal coating, vinyl siding, metal siding, injection molded products, vinyl windows, aluminum windows, and other products and services to customers throughout the United States and Canada and affiliated territories, including international builders who resell to end users. Sales are primarily denominated in U.S. dollars. Credit sales do not normally require a pledge of collateral; however, various types of liens may be filed to enhance the collection process and we require payment prior to shipment for certain international shipments.
Net Sales	Net Sales The Company adopted Accounting Standards Update (“ASU”) No. 2014-09, Revenue from Contracts with Customers (“ASU 2014-09”), as of October 29, 2018. ASU 2014-09 provides enhancements to the quality and consistency of how revenue is reported while also improving comparability in the financial statements of companies reporting using International Financial Reporting Standards and GAAP. The core principle of this update is that an entity should recognize revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. The Company enters into contracts that pertain to products, which are accounted for as separate performance obligations and are typically one year or less in duration. The Company does not exercise significant judgment in determining the timing for the satisfaction of performance obligations or the transaction price. Revenue is measured as the amount of consideration expected to be received in exchange for our products. The Company has elected to apply the practical expedient provided for in ASU No. 2014-09 and has not disclosed information regarding remaining performance obligations that have original expected durations of one year or less. Revenue is generally recognized when the product has shipped from our facility and control has transferred to the customer. For a portion of our business, when we process customer owned material, control is deemed to transfer to the customer as the processing is being completed. Our revenues are adjusted for variable consideration, which includes customer volume rebates and prompt payment discounts. We measure variable consideration by estimating expected outcomes using analysis and inputs based upon anticipated performance, historical data, and current and forecasted information. Customer returns are recorded as a reduction to sales on an actual basis throughout the year and also include an estimate at the end of each reporting period for future customer returns related to sales recorded prior to the end of the period. The Company generally estimates customer returns based upon the time lag that historically occurs between the sale date and the return date while also factoring in any new business conditions that might impact the historical analysis such as new product introduction. Measurement of variable consideration is reviewed by management periodically and revenue is adjusted accordingly. We do not have significant financing components. Shipping and handling activities performed by us are considered activities to fulfill the sales of our products. Amounts billed for shipping and handling are included in net sales, while costs incurred for shipping and handling are included in cost of sales. In accordance with certain contractual arrangements, we receive payment from our customers in advance related to performance obligations that are to be satisfied in the future and recognize such payments as deferred revenue, primarily related to the Company's weathertightness warranties (see Note 12 — Warranty).
Fair Value Measurements	Fair Value Measurements ASC Subtopic 820-10, Fair Value Measurements and Disclosures , requires us to use valuation techniques to measure fair value that maximize the use of observable inputs and minimize the use of unobservable inputs. These inputs are prioritized as follows: Level 1 : Observable inputs such as quoted prices for identical assets or liabilities in active markets. Level 2 : Other inputs that are observable directly or indirectly, such as quoted prices for similar assets or liabilities or market-corroborated inputs. Level 3 : Unobservable inputs for which there is little or no market data and which require us to develop our own assumptions about how market participants would price the assets or liabilities. The following is a description of the valuation methodologies used for assets and liabilities measured at fair value. There have been no changes in the methodologies used as of October 3, 2020 and December 31, 2019. Money market: Money market funds have original maturities of three months or less. The original cost of these assets approximates fair value due to their short-term maturity. Mutual funds: Mutual funds are valued at the closing price reported in the active market in which the mutual fund is traded. Assets held for sale: Assets held for sale are valued based on current market conditions, prices of similar assets in similar condition and expected proceeds from the sale of the assets, representative of Level 3 inputs. Deferred compensation plan liability: Deferred compensation plan liability is comprised of phantom investments in the deferred compensation plan and is valued at the closing price reported in the active markets in which the money market and mutual funds are traded. Interest rate swap liability: Interest rate swap liabilities are based on cash flow hedge contracts that have fixed rate structures and are measured against market-based LIBOR yield curves. These interest rate swaps were classified within Level 2 of the fair value hierarchy because they were valued using alternative pricing sources or models that utilized market observable inputs, including current and forward interest rates.
Adopted Accounting Pronouncements and Recent Accounting Pronouncements	Adopted Accounting Pronouncements In June 2016, the Financial Accounting Standards Board ("FASB") issued ASU 2016-13 Financial Instruments—Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments. This ASU requires an entity to measure all expected credit losses for financial assets, including trade receivables, held at the reporting date based on historical experience, current conditions, and reasonable and supportable forecasts. Entities will now incorporate forward-looking information based on expected losses to estimate credit losses. Effective January 1, 2020, the Company adopted this guidance on a modified retrospective basis, pursuant to which it recorded a $0.7 million adjustment to increase the opening balance of accumulated deficit as of January 1, 2020 for the impact of applying the new standard. The adjustment related to recording an incremental credit loss to the accounts receivable allowance for doubtful accounts at the beginning of the first period in which the accounting standard is effective. Additional credit loss disclosures are included in Note 1 — Summary of Significant Accounting Policies . In August 2018, the FASB issued ASU 2018-13, Fair Value Measurement (Topic 820): Disclosure Framework—Changes to the Disclosure Requirements for Fair Value Measurement, which modifies disclosure requirements for fair value measurements under FASB Accounting Standards Codification ("ASC") 820, Fair Value Measurement. Effective January 1, 2020, the Company adopted this guidance. The application of ASU 2018-13 did not have a material effect on consolidated financial statements. In August 2018, the FASB issued ASU 2018-14, Compensation—Retirement Benefits—Defined Benefit Plans—General (Subtopic 715-20): Disclosure Framework—Changes to the Disclosure Requirements for Defined Benefit Plans , which removes disclosures no longer considered cost beneficial, clarifies the specific requirements of disclosures and adds disclosure requirements identified as relevant. Effective January 1, 2020, the Company adopted this guidance. The application of ASU 2018-14 did not have a material effect on consolidated financial statements. Recent Accounting Pronouncements In December 2019, the FASB issued ASU 2019-12, Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes, which simplifies the accounting for income taxes by removing certain exceptions to the general principles in Topic 740 and also improves consistent application of and simplifies GAAP for other areas of Topic 740 by clarifying and amending existing guidance. The Company will be required to adopt this guidance in the annual and interim periods for our fiscal year ending December 31, 2021, with early adoption permitted. The Company is evaluating the impact of adopting this guidance. In March 2020, the FASB issued ASU 2020-04, Reference Rate Reform (Topic 848): Facilitation of the Effects of Reference Rate Reform on Financial Reporting , which provides optional guidance to ease the potential burden in accounting for reference rate reform on financial reporting. The amendments in this ASU are elective, apply to all entities that have contracts, hedging relationships, and other transactions that reference LIBOR or another reference rate expected to be discontinued because of rate reform, and are effective as of March 12, 2020 through December 31, 2022. The Company is evaluating the impact of electing to apply the amendments in this guidance. Additionally, there were various other accounting standards and interpretations issued that the Company has not yet been required to adopt, none of which is expected to have a material impact on the Company’s consolidated financial statements going forward.
Leases	The Company leases certain manufacturing, warehouse and distribution locations, vehicles and equipment, including fleet vehicles. Many of these leases have options to terminate prior to or extend beyond the end of the term. The exercise of the majority of lease renewal options is at the Company’s sole discretion. Some lease agreements have variable payment terms, the majority of these are real estate agreements in which future increases in rent are based on an index. Lease agreements do not contain any material residual value guarantees or material restrictive covenants. Operating lease liabilities are recognized based on the present value of the future minimum lease payments over the reasonably expected holding period at commencement date. Few of the Company’s lease contracts provide a readily determinable implicit rate. For lease contracts without a readily determinable implicit rate, an estimated incremental borrowing rate (“IBR”) is utilized, based on information available at the inception of the lease. The IBR represents an estimate of the interest rate we would incur at lease commencement to borrow an amount equal to the lease payments on a collateralized basis over the term of the lease.

SUMMARY OF SIGNIFICANT ACCOUN_3

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Tables)	9 Months Ended
	Oct. 03, 2020
Accounting Policies [Abstract]
Schedule of Cash and Cash Equivalents	The following table provides a reconciliation of cash, cash equivalents and restricted cash reported within the consolidated balance sheets that total the amounts shown in the consolidated statements of cash flows (in thousands): October 3, December 31, Cash and cash equivalents $ 627,603 $ 98,386 Restricted cash (1) 6,223 3,921 Total cash, cash equivalents and restricted cash shown in the consolidated statements of cash flows $ 633,826 $ 102,307 (1) Restricted cash primarily relates to escrow balances held for an outstanding earn-out agreement and working capital and other indemnification agreements.
Restrictions on Cash and Cash Equivalents	The following table provides a reconciliation of cash, cash equivalents and restricted cash reported within the consolidated balance sheets that total the amounts shown in the consolidated statements of cash flows (in thousands): October 3, December 31, Cash and cash equivalents $ 627,603 $ 98,386 Restricted cash (1) 6,223 3,921 Total cash, cash equivalents and restricted cash shown in the consolidated statements of cash flows $ 633,826 $ 102,307 (1) Restricted cash primarily relates to escrow balances held for an outstanding earn-out agreement and working capital and other indemnification agreements.
Rollforward of Reserve for Uncollectible Accounts	The following table represents the rollforward of the reserve for uncollectible accounts for the periods indicated (in thousands): Nine Months Ended October 3, 2020 Ending balance, December 31, 2019 $ 9,962 Cumulative effect of accounting change (1) 678 Provision for expected credit losses 3,762 Amounts charged against allowance for credit losses, net of recoveries (1,801) Allowance for credit losses of acquired company at date of acquisition 810 Ending balance, October 3, 2020 $ 13,411 (1) Cumulative effect of accounting change reflects the modified retrospective effect of adopting ASU 2016-13 Financial Instruments—Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments (See Note 2 — Accounting Pronouncements )
Disaggregation of Revenue by Segment	The following table presents disaggregated revenue disclosure details of net sales by segment (in thousands): Three Months Ended Nine Months Ended October 3, September 28, October 3, September 28, Windows Net Sales Disaggregation: Vinyl windows (1) $ 465,472 $ 473,202 $ 1,283,337 $ 1,334,747 Aluminum windows (1) 22,056 18,404 61,338 56,490 Other (1) 13,786 12,732 33,364 43,342 Total $ 501,314 $ 504,338 $ 1,378,039 $ 1,434,579 Siding Net Sales Disaggregation: Vinyl siding $ 146,585 $ 148,912 $ 387,559 $ 400,220 Metal 75,477 75,933 192,567 199,265 Injection molded 20,460 17,429 49,556 47,163 Stone 20,988 32,254 61,999 70,441 Other products & services 58,388 41,271 156,509 123,512 Total $ 321,898 $ 315,799 $ 848,190 $ 840,601 Commercial Net Sales Disaggregation: Metal building products $ 281,339 $ 320,028 $ 842,863 $ 914,623 Insulated metal panels 89,088 109,322 260,410 332,403 Metal coil coating 33,614 35,556 96,498 123,126 Total $ 404,041 $ 464,906 $ 1,199,771 $ 1,370,152 Total Net Sales: $ 1,227,253 $ 1,285,043 $ 3,426,000 $ 3,645,332 (1) Aluminum windows and other net sales for the three months ended September 28, 2019 includes $6.5 million and $1.4 million, respectively, of net sales previously included in vinyl windows. Aluminum windows and other net sales for the nine months ended September 28, 2019 includes $16.8 million and $3.8 million, respectively, of net sales previously included in vinyl windows.

ACQUISITIONS (Tables)

ACQUISITIONS (Tables)	9 Months Ended
	Oct. 03, 2020
Business Combinations [Abstract]
Schedule of Estimated Fair Value of Assets and Liabilities Assumed from Acquisition	The Company determined the fair value of the tangible and intangible assets and the liabilities acquired, and recorded goodwill based on the excess of the fair value of the acquisition consideration over such fair values, as follows (in thousands): Assets acquired: Cash $ 143 Accounts receivable 7,235 Inventories 670 Prepaid expenses and other current assets 277 Property, plant and equipment 1,042 Lease right of use assets 445 Intangible assets (trade names/customer relationships) 22,350 Goodwill 11,721 Other assets 680 Total assets acquired 44,563 Liabilities assumed: Accounts payable 1,126 Other accrued expenses 1,005 Lease liabilities 339 Other long-term liabilities 109 Total liabilities assumed 2,579 Net assets acquired $ 41,984 The Company determined the fair value of the tangible and intangible assets and the liabilities acquired, and recorded goodwill based on the excess of the fair value of the acquisition consideration over such fair values, as follows (in thousands): Assets acquired: Restricted cash $ 3,379 Accounts receivable 16,825 Inventories 13,062 Prepaid expenses and other current assets 3,677 Property, plant and equipment 14,295 Lease right of use assets 11,372 Intangible assets (trade names/customer relationships) 91,170 Goodwill 63,543 Deferred taxes 474 Other assets 157 Total assets acquired 217,954 Liabilities assumed: Accounts payable 5,910 Other accrued expenses 14,666 Lease liabilities 11,365 Other long-term liabilities 3,450 Total liabilities assumed 35,391 Net assets acquired $ 182,563
Business Acquisition, Pro Forma Information	The following table provides unaudited supplemental pro forma results for Cornerstone, prepared in accordance with ASC 805, for the three and nine months ended October 3, 2020 and September 28, 2019 as if the Kleary and ESW (defined below) acquisitions had occurred on January 1, 2019 (in thousands except for per share data): Three Months Ended Nine Months Ended October 3, September 28, October 3, September 28, Net sales $ 1,227,253 $ 1,298,307 $ 3,434,358 $ 3,694,102 Net income (loss) applicable to common shares 30,516 25,164 (482,789) (19,843) Net income (loss) per common share: Basic $ 0.24 $ 0.20 $ (3.84) $ (0.16) Diluted $ 0.24 $ 0.20 $ (3.84) $ (0.16)

RESTRUCTURING (Tables)

RESTRUCTURING (Tables)	9 Months Ended
	Oct. 03, 2020
Restructuring and Related Activities [Abstract]
Restructuring and Related Costs	The following table summarizes our restructuring plan costs and charges related to the restructuring plans for the period indicated, which are recorded in restructuring and impairment charges in the Company’s consolidated statements of operations (in thousands): Three Months Ended Nine Months Ended October 3, 2020 October 3, 2020 Severance $ 1,074 $ 23,563 Asset impairments 1,169 4,938 Other restructuring costs 675 3,820 Total restructuring costs $ 2,918 $ 32,321
Schedule of Restructuring Reserve by Type of Cost	The following table summarizes our severance liability and cash payments made pursuant to the restructuring plans from inception through October 3, 2020 (in thousands): Windows Siding Commercial Corporate Total Balance, December 31, 2018 $ — $ 85 $ — $ 2,333 $ 2,418 Costs incurred 1,094 1,834 2,721 4,009 9,658 Cash payments (676) (1,437) (2,721) (4,579) (9,413) Balance, December 31, 2019 $ 418 $ 482 $ — $ 1,763 $ 2,663 Costs incurred 3,389 2,367 16,413 1,394 23,563 Cash payments (3,368) (2,169) (14,314) (1,394) (21,245) Balance, October 3, 2020 $ 439 $ 680 $ 2,099 $ 1,763 $ 4,981

GOODWILL (Tables)

GOODWILL (Tables)	9 Months Ended
	Oct. 03, 2020
Goodwill and Intangible Assets Disclosure [Abstract]
Schedule of Goodwill	The Company’s goodwill balance and changes in the carrying amount of goodwill by segment follows (in thousands): Windows Siding Commercial Total Balance, December 31, 2019 $ 714,023 $ 807,280 $ 148,291 $ 1,669,594 Goodwill recognized from Kleary Acquisition — 11,721 — 11,721 Impairment (320,990) (176,774) (5,407) (503,171) Currency translation 1,885 7,081 — 8,966 Purchase accounting adjustments — 2,882 — 2,882 Balance, October 3, 2020 $ 394,918 $ 652,190 $ 142,884 $ 1,189,992

INVENTORIES (Tables)

INVENTORIES (Tables)	9 Months Ended
	Oct. 03, 2020
Inventory Disclosure [Abstract]
Schedule of Inventory Components	The components of inventory are as follows (in thousands): October 3, 2020 December 31, 2019 Raw materials $ 232,627 $ 239,063 Work in process and finished goods 176,270 200,131 Total inventory $ 408,897 $ 439,194

INTANGIBLES (Tables)

INTANGIBLES (Tables)	9 Months Ended
	Oct. 03, 2020
Goodwill and Intangible Assets Disclosure [Abstract]
Schedule of Finite-Lived Intangible Assets	The table that follows presents the major components of intangible assets as of October 3, 2020 and December 31, 2019 (in thousands): Range of Life (Years) Weighted Average Amortization Period (Years) Cost Accumulated Amortization Net Carrying Value As of October 3, 2020 Amortized intangible assets: Trademarks/Trade names 5 – 15 8 $ 248,021 $ (51,658) $ 196,363 Customer lists and relationships 7 – 20 10 1,754,347 (327,577) 1,426,770 Total intangible assets 10 $ 2,002,368 $ (379,235) $ 1,623,133 As of December 31, 2019 Amortized intangible assets: Trademarks/Trade names 5 – 15 9 $ 252,942 $ (38,010) $ 214,932 Customer lists and relationships 9 – 20 11 1,737,060 (211,292) 1,525,768 Total intangible assets 10 $ 1,990,002 $ (249,302) $ 1,740,700

LEASES (Tables)

LEASES (Tables)	9 Months Ended
	Oct. 03, 2020
Leases [Abstract]
Schedules of Lease Costs	Weighted average information about the Company’s lease portfolio as of October 3, 2020 was as follows: Weighted-average remaining lease term 5.5 years Weighted-average IBR 6.08 % Operating lease costs were as follows (in thousands): Three Months Ended Nine Months Ended October 3, September 28, October 3, September 28, Operating lease costs Fixed lease costs $ 21,220 $ 23,903 $ 78,183 $ 77,125 Variable lease costs (1) 19,013 8,654 54,188 27,868 (1) Includes short-term lease costs, which are immaterial.
Cash and Non-cash Activities of Leases	Cash and non-cash activities were as follows (in thousands): Three Months Ended Nine Months Ended October 3, September 28, October 3, September 28, Cash paid for amounts included in the measurement of lease liabilities: Operating cash flows for operating leases $ 24,853 $ 23,463 $ 80,241 $ 66,936 Right-of-use assets obtained in exchange for new operating lease liabilities $ 2,070 $ 47,236 $ 18,940 $ 372,269
Schedule of Future Minimum Lease Payments	Future minimum lease payments under non-cancelable leases as of October 3, 2020 were as follows (in thousands): Operating Leases 2020 (excluding the nine months ended October 3, 2020) $ 17,730 2021 82,979 2022 67,882 2023 42,451 2024 31,875 Thereafter 88,848 Total future minimum lease payments 331,765 Less: interest 51,911 Present value of future minimum lease payments $ 279,854 As of October 3, 2020 Current portion of lease liabilities $ 69,408 Long-term portion of lease liabilities 210,446 Total $ 279,854

EARNINGS PER COMMON SHARE (Tabl

EARNINGS PER COMMON SHARE (Tables)	9 Months Ended
	Oct. 03, 2020
Earnings Per Share [Abstract]
Schedule of Earnings Per Share, Basic and Diluted	The reconciliation of the numerator and denominator used for the computation of basic and diluted earnings per common share is as follows (in thousands, except per share data): Three Months Ended Nine Months Ended October 3, September 28, October 3, September 28, Numerator for Basic and Diluted Earnings Per Common Share Net income (loss) applicable to common shares $ 30,028 $ 24,790 $ (484,658) $ (17,320) Denominator for Basic and Diluted Earnings Per Common Share Weighted average basic number of common shares outstanding 125,100 125,557 125,655 125,526 Common stock equivalents: Employee stock options 189 1 — — PSUs and Performance Share Awards — — — — Weighted average diluted number of common shares outstanding 125,289 125,558 125,655 125,526 Basic income (loss) per common share $ 0.24 $ 0.20 $ (3.86) $ (0.14) Diluted income (loss) per common share $ 0.24 $ 0.20 $ (3.86) $ (0.14) Incentive Plan securities excluded from dilution (1) 2,146 5,189 3,338 4,974 (1) Represents securities not included in the computation of diluted earnings per common share because their effect would have been anti-dilutive.

WARRANTY (Tables)

WARRANTY (Tables)	9 Months Ended
	Oct. 03, 2020
Product Warranties Disclosures [Abstract]
Schedule of Acquired Accrued Warranty Obligation and Deferred Warranty Revenue	The following table represents the rollforward of our accrued warranty obligation and deferred warranty revenue activity for the nine months ended October 3, 2020 and September 28, 2019 (in thousands): Nine Months Ended October 3, 2020 September 28, 2019 Beginning balance $ 216,173 $ 134,515 Acquisition 109 — Purchase accounting adjustments — 84,280 Warranties sold 1,885 2,313 Revenue recognized (2,054) (2,075) Expense 23,257 22,006 Settlements (22,645) (22,285) Ending balance 216,725 218,754 Less: current portion 27,201 31,294 Total, less current portion $ 189,524 $ 187,460

DEFINED BENEFIT PLANS (Tables)

DEFINED BENEFIT PLANS (Tables)	9 Months Ended
	Oct. 03, 2020
Retirement Benefits [Abstract]
Schedule of Accumulated and Projected Benefit Obligations	The following tables set forth the components of the net periodic benefit cost, before tax for the periods indicated (in thousands): Defined Benefit Plans Three Months Ended Nine Months Ended October 3, September 28, October 3, September 28, Service cost $ 11 $ 11 $ 34 $ 32 Interest cost 802 974 2,405 2,922 Expected return on assets (1,398) (1,234) (4,193) (3,701) Amortization of prior service cost 16 15 47 43 Amortization of net actuarial loss 753 704 2,256 2,112 Net periodic benefit cost $ 184 $ 470 $ 549 $ 1,408 OPEB Plans Three Months Ended Nine Months Ended October 3, September 28, October 3, September 28, Service cost $ 4 $ 6 $ 13 $ 17 Interest cost 59 66 178 197 Amortization of net actuarial loss 27 — 81 — Net periodic benefit cost $ 90 $ 72 $ 272 $ 214

LONG-TERM DEBT (Tables)

LONG-TERM DEBT (Tables)	9 Months Ended
	Oct. 03, 2020
Debt Disclosure [Abstract]
Schedule Of Debt	Debt is comprised of the following (in thousands): October 3, December 31, Asset-based revolving credit facility due April 2023 $ — $ 70,000 Term loan facility due April 2025 2,504,372 2,523,587 Cash flow revolver due April 2023 — — 8.00% senior notes due April 2026 645,000 645,000 6.125% senior notes due January 2029 500,000 — Less: unamortized discounts and unamortized deferred financing costs (1) (56,470) (56,063) Total long-term debt, net of unamortized discounts and unamortized deferred financing costs 3,592,902 3,182,524 Less: current portion of long-term debt 25,600 25,600 Total long-term debt, less current portion $ 3,567,302 $ 3,156,924 (1) Includes the unamortized discounts associated with the term loan facility and 8.00 % senior notes due April 2026, and the unamortized deferred financing costs associated with the term loan facility and 6.125% senior notes due January 2029. The unamortized deferred financing costs associated with the asset-based revolving credit facilities of $1.9 million and $2.4 million as of October 3, 2020 and December 31, 2019, respectively, are classified in other assets on the consolidated balance sheets.
Schedule of Long-term Debt Instruments	At October 3, 2020, the interest rates on the Current Term Loan Facility were as follows: October 3, 2020 Interest rate 3.9 % Effective interest rate 6.51 % October 3, 2020 Excess availability $ 570,000 Revolving loans outstanding — Letters of credit outstanding 36,500

FAIR VALUE OF FINANCIAL INSTR_2

FAIR VALUE OF FINANCIAL INSTRUMENTS AND FAIR VALUE MEASUREMENTS (Tables)	9 Months Ended
	Oct. 03, 2020
Fair Value Disclosures [Abstract]
Schedule of Fair Value Not Currently Recognized on Balance sheet	The fair values of the remaining financial instruments not currently recognized at fair value on our consolidated balance sheets at the respective period ends were (in thousands): October 3, 2020 December 31, 2019 Carrying Fair Value Carrying Fair Value Term Loan Facility $ 2,504,372 $ 2,479,328 $ 2,523,587 $ 2,514,906 8.00% Senior Notes 645,000 675,638 645,000 670,800 6.125% Senior Notes 500,000 505,000 — —
Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis	The following tables summarize information regarding our financial assets and liabilities that are measured at fair value on a recurring basis as of October 3, 2020 and December 31, 2019, segregated by the level of the valuation inputs within the fair value hierarchy utilized to measure fair value (in thousands): October 3, 2020 Level 1 Level 2 Level 3 Total Assets: Short-term investments in deferred compensation plan (1) : Money market $ 197 $ — $ — $ 197 Mutual funds – Growth 397 — — 397 Mutual funds – Blend 890 — — 890 Mutual funds – Foreign blend 282 — — 282 Mutual funds – Fixed income — 151 — 151 Total short-term investments in deferred compensation plan (2) 1,766 151 — 1,917 Total assets $ 1,766 $ 151 $ — $ 1,917 Liabilities: Deferred compensation plan liability (2) $ — $ 2,154 $ — $ 2,154 Interest rate swap liability (3) — 83,304 — 83,304 Total liabilities $ — $ 85,458 $ — $ 85,458 December 31, 2019 Level 1 Level 2 Level 3 Total Assets: Short-term investments in deferred compensation plan (1) : Money market $ 2 $ — $ — $ 2 Mutual funds – Growth 1,044 — — 1,044 Mutual funds – Blend 1,769 — — 1,769 Mutual funds – Foreign blend 572 — — 572 Mutual funds – Fixed income — 389 — 389 Total short-term investments in deferred compensation plan (2) 3,387 389 — 3,776 Total assets $ 3,387 $ 389 $ — $ 3,776 Liabilities: Deferred compensation plan liability (2) $ — $ 3,847 $ — $ 3,847 Interest rate swap liability (3) — 29,988 — 29,988 Total liabilities $ — $ 33,835 $ — $ 33,835 (1) Unrealized holding losses for the three months ended September 28, 2019 were $0.1 million. Unrealized holding gains (losses) for the nine months ended October 3, 2020 and September 28, 2019 were $(0.7) million and $0.4 million, respectively. These unrealized holding gains (losses) were substantially offset by changes in the deferred compensation plan liability. (2) The Company records the short-term investments in deferred compensation plan within investments in debt and equity securities, at market, and the deferred compensation plan liability within accrued compensation and benefits on the consolidated balance sheets. (3) In May 2019, the Company entered into four-year interest rate swaps to mitigate variability in forecasted interest payments on $1,500.0 million of the Company’s term loan secured variable debt. The interest rate swaps effectively convert a portion of the floating rate interest payments into a fixed rate interest payment. There are three interest rate swaps that cover $500.0

SEGMENT INFORMATION (Tables)

SEGMENT INFORMATION (Tables)	9 Months Ended
	Oct. 03, 2020
Segment Reporting [Abstract]
Schedule of Sales, Operating Income, and Total Assets for Operating Segments	The following table represents summary financial data attributable to the segments for the periods indicated (in thousands): Three Months Ended Nine Months Ended October 3, September 28, October 3, September 28, Net sales: Windows $ 501,314 $ 504,338 $ 1,378,039 $ 1,434,579 Siding 321,898 315,799 848,190 840,601 Commercial 404,041 464,906 1,199,771 1,370,152 Total net sales $ 1,227,253 $ 1,285,043 $ 3,426,000 $ 3,645,332 Operating income (loss): Windows $ 37,295 $ 34,446 $ (252,794) $ 62,039 Siding 45,313 37,063 (92,916) 51,346 Commercial 56,137 59,317 109,642 142,436 Corporate (34,766) (35,266) (101,819) (106,695) Total operating income (loss) 103,979 95,560 (337,887) 149,126 Unallocated other expense, net (50,402) (56,293) (159,056) (170,894) Income (loss) before taxes $ 53,577 $ 39,267 $ (496,943) $ (21,768) October 3, December 31, Total assets: Windows $ 1,820,255 $ 2,166,220 Siding 2,158,395 2,289,310 Commercial 878,623 963,291 Corporate 617,708 145,525 Total assets $ 5,474,981 $ 5,564,346

SUMMARY OF SIGNIFICANT ACCOUN_4

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Narrative (Details) - Ply Gem - shares	Nov. 16, 2018	Oct. 03, 2020
Business Acquisition [Line Items]
Shares issued in transaction (in shares)	58,709,067
Sale of stock, ownership percentage issued	47.00%
Equity not issued in merger (in shares)		57,103

SUMMARY OF SIGNIFICANT ACCOUN_5

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Reconciliation of Cash, Cash Equivalents and Restricted Cash (Details) - USD ($) $ in Thousands	Oct. 03, 2020	Dec. 31, 2019	Sep. 28, 2019	Dec. 31, 2018
Accounting Policies [Abstract]
Cash and cash equivalents	$ 627,603	$ 98,386
Restricted cash	6,223	3,921
Total cash, cash equivalents and restricted cash shown in the consolidated statements of cash flows	$ 633,826	$ 102,307	$ 109,116	$ 147,607

SUMMARY OF SIGNIFICANT ACCOUN_6

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Rollforward of Uncollectible Accounts (Details) - USD ($) $ in Thousands	Jan. 01, 2020	Oct. 03, 2020	Sep. 28, 2019
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Ending balance, December 31, 2019	$ 9,962	$ 9,962
Cumulative effect of accounting change	$ 9,962	13,411
Provision for expected credit losses		3,762	$ (492)
Amounts charged against allowance for credit losses, net of recoveries		(1,801)
Allowance for credit losses of acquired company at date of acquisition		810
Ending balance, October 3, 2020		$ 13,411
Accounting Standards Update [Extensible List]	us-gaap:AccountingStandardsUpdate201613Member	us-gaap:AccountingStandardsUpdate201613Member
Cumulative Effect, Period of Adoption, Adjustment
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Ending balance, December 31, 2019	$ 678	$ 678
Cumulative effect of accounting change	$ 678	$ 678

SUMMARY OF SIGNIFICANT ACCOUN_7

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Oct. 03, 2020	Sep. 28, 2019	Oct. 03, 2020	Sep. 28, 2019
Disaggregation of Revenue [Line Items]
Total net sales	$ 1,227,253	$ 1,285,043	$ 3,426,000	$ 3,645,332
Windows
Disaggregation of Revenue [Line Items]
Total net sales	501,314	504,338	1,378,039	1,434,579
Windows | Vinyl windows
Disaggregation of Revenue [Line Items]
Total net sales	465,472	473,202	1,283,337	1,334,747
Windows | Aluminum windows
Disaggregation of Revenue [Line Items]
Total net sales	22,056	18,404	61,338	56,490
Windows | Aluminum windows | Revision of Prior Period, Reclassification, Adjustment [Member]
Disaggregation of Revenue [Line Items]
Total net sales		6,500		16,800
Windows | Other products & services
Disaggregation of Revenue [Line Items]
Total net sales	13,786	12,732	33,364	43,342
Windows | Other products & services | Revision of Prior Period, Reclassification, Adjustment [Member]
Disaggregation of Revenue [Line Items]
Total net sales		1,400		3,800
Windows | Reclassification to aluminum windows | Revision of Prior Period, Reclassification, Adjustment [Member]
Disaggregation of Revenue [Line Items]
Total net sales		(6,500)		(16,800)
Windows | Reclassification to other | Revision of Prior Period, Reclassification, Adjustment [Member]
Disaggregation of Revenue [Line Items]
Total net sales		(1,400)		(3,800)
Siding
Disaggregation of Revenue [Line Items]
Total net sales	321,898	315,799	848,190	840,601
Siding | Other products & services
Disaggregation of Revenue [Line Items]
Total net sales	58,388	41,271	156,509	123,512
Siding | Vinyl siding
Disaggregation of Revenue [Line Items]
Total net sales	146,585	148,912	387,559	400,220
Siding | Metal
Disaggregation of Revenue [Line Items]
Total net sales	75,477	75,933	192,567	199,265
Siding | Injection molded
Disaggregation of Revenue [Line Items]
Total net sales	20,460	17,429	49,556	47,163
Siding | Stone
Disaggregation of Revenue [Line Items]
Total net sales	20,988	32,254	61,999	70,441
Commercial
Disaggregation of Revenue [Line Items]
Total net sales	404,041	464,906	1,199,771	1,370,152
Commercial | Metal building products
Disaggregation of Revenue [Line Items]
Total net sales	281,339	320,028	842,863	914,623
Commercial | Insulated metal panels
Disaggregation of Revenue [Line Items]
Total net sales	89,088	109,322	260,410	332,403
Commercial | Metal coil coating
Disaggregation of Revenue [Line Items]
Total net sales	$ 33,614	$ 35,556	$ 96,498	$ 123,126

ACCOUNTING PRONOUNCEMENTS (Deta

ACCOUNTING PRONOUNCEMENTS (Details) - USD ($) $ in Thousands	Jan. 01, 2020	Oct. 03, 2020	Dec. 31, 2019
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Accounting Standards Update [Extensible List]	us-gaap:AccountingStandardsUpdate201613Member	us-gaap:AccountingStandardsUpdate201613Member
Cumulative Effect, Period of Adoption, Adjustment
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Cumulative effect of accounting change			$ 678
Retained Earnings (Deficit) | Cumulative Effect, Period of Adoption, Adjustment
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Cumulative effect of accounting change	$ 700		$ 678

ACQUISITIONS - Narrative (Detai

ACQUISITIONS - Narrative (Details) $ in Thousands	Mar. 02, 2020USD ($)	Feb. 20, 2019USD ($)	Oct. 03, 2020USD ($)	Jul. 04, 2020USD ($)	Oct. 03, 2020USD ($)acquisition	Dec. 31, 2019USD ($)
Business Acquisition [Line Items]
Goodwill			$ 1,189,992		$ 1,189,992	$ 1,669,594
Number of acquisitions | acquisition					2
Kleary Masonry, Inc.
Business Acquisition [Line Items]
Percentage of outstanding interests acquired	100.00%
Total cash consideration transferred	$ 40,000
Working capital adjustments				$ 2,000
Goodwill	11,721
Acquisition related expenses			6,900		$ 8,100
Net sales of acquiree included in our financial statements			13,300		25,900
Net income (loss) of acquiree included in our financial statements			(900)		800
Environmental Stoneworks
Business Acquisition [Line Items]
Percentage of outstanding interests acquired		100.00%
Total cash consideration transferred		$ 182,600
Goodwill		$ 63,543
Siding
Business Acquisition [Line Items]
Goodwill			$ 652,190		$ 652,190	$ 807,280
Siding | Kleary Masonry, Inc.
Business Acquisition [Line Items]
Goodwill	$ 11,700

ACQUISITIONS - Schedule of Asse

ACQUISITIONS - Schedule of Assets Acquired and Liabilities Assumed (Details) - USD ($) $ in Thousands	Oct. 03, 2020	Mar. 02, 2020	Dec. 31, 2019	Feb. 20, 2019
Assets acquired:
Goodwill	$ 1,189,992		$ 1,669,594
Liabilities assumed:
Lease liabilities	$ 279,854
Kleary Masonry, Inc.
Assets acquired:
Cash		$ 143
Accounts receivable		7,235
Inventories		670
Prepaid expenses and other current assets		277
Property, plant and equipment		1,042
Lease right of use assets		445
Intangible assets (trade names/customer relationships)		22,350
Goodwill		11,721
Other assets		680
Total assets acquired		44,563
Liabilities assumed:
Accounts payable		1,126
Other accrued expenses		1,005
Lease liabilities		339
Other long-term liabilities		109
Total liabilities assumed		2,579
Net assets acquired		$ 41,984
Environmental Stoneworks
Assets acquired:
Restricted cash				$ 3,379
Accounts receivable				16,825
Inventories				13,062
Prepaid expenses and other current assets				3,677
Property, plant and equipment				14,295
Lease right of use assets				11,372
Intangible assets (trade names/customer relationships)				91,170
Goodwill				63,543
Deferred taxes				474
Other assets				157
Total assets acquired				217,954
Liabilities assumed:
Accounts payable				5,910
Other accrued expenses				14,666
Lease liabilities				11,365
Other long-term liabilities				3,450
Total liabilities assumed				35,391
Net assets acquired				$ 182,563

ACQUISITIONS - Schedule of Pro

ACQUISITIONS - Schedule of Pro Forma Information (Details) - Kleary Masonry, Inc. - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Oct. 03, 2020	Sep. 28, 2019	Oct. 03, 2020	Sep. 28, 2019
Business Acquisition, Pro Forma Information, Nonrecurring Adjustment [Line Items]
Net sales	$ 1,227,253	$ 1,298,307	$ 3,434,358	$ 3,694,102
Net income (loss) applicable to common shares	$ 30,516	$ 25,164	$ (482,789)	$ (19,843)
Net income (loss) per common share:
Basic (in USD per share)	$ 0.24	$ 0.20	$ (3.84)	$ (0.16)
Diluted (in USD per share)	$ 0.24	$ 0.20	$ (3.84)	$ (0.16)

RESTRUCTURING (Details)

RESTRUCTURING (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended	12 Months Ended
	Oct. 03, 2020	Apr. 04, 2020	Oct. 03, 2020	Dec. 31, 2019
Restructuring Cost and Reserve [Line Items]
Restructuring costs	$ 2,918		$ 32,321
Total restructuring costs incurred to date	50,400		50,400
Asset impairment		$ 3,100	4,900
Restructuring Reserve [Roll Forward]
Restructuring reserve, beginning balance		2,663	2,663	$ 2,418
Costs incurred			23,563	9,658
Cash payments			(21,245)	(9,413)
Restructuring reserve, ending balance	4,981		4,981	2,663
Equipment Costs
Restructuring Cost and Reserve [Line Items]
Asset impairment			3,400
Right-of-Use Assets
Restructuring Cost and Reserve [Line Items]
Asset impairment			1,500
Restructuring and Impairment Costs
Restructuring Cost and Reserve [Line Items]
Restructuring costs			32,100
Cost of Goods Sold
Restructuring Cost and Reserve [Line Items]
Restructuring costs			200
Windows
Restructuring Cost and Reserve [Line Items]
Restructuring costs			7,200
Restructuring Reserve [Roll Forward]
Restructuring reserve, beginning balance		418	418	0
Costs incurred			3,389	1,094
Cash payments			(3,368)	(676)
Restructuring reserve, ending balance	439		439	418
Siding
Restructuring Cost and Reserve [Line Items]
Restructuring costs			2,900
Restructuring Reserve [Roll Forward]
Restructuring reserve, beginning balance		482	482	85
Costs incurred			2,367	1,834
Cash payments			(2,169)	(1,437)
Restructuring reserve, ending balance	680		680	482
Commercial
Restructuring Cost and Reserve [Line Items]
Restructuring costs			20,400
Restructuring Reserve [Roll Forward]
Restructuring reserve, beginning balance		0	0	0
Costs incurred			16,413	2,721
Cash payments			(14,314)	(2,721)
Restructuring reserve, ending balance	2,099		2,099	0
Corporate
Restructuring Cost and Reserve [Line Items]
Restructuring gain			1,800
Restructuring Reserve [Roll Forward]
Restructuring reserve, beginning balance		$ 1,763	1,763	2,333
Costs incurred			1,394	4,009
Cash payments			(1,394)	(4,579)
Restructuring reserve, ending balance	1,763		1,763	$ 1,763
Severance
Restructuring Cost and Reserve [Line Items]
Restructuring costs	1,074		23,563
Asset impairments
Restructuring Cost and Reserve [Line Items]
Restructuring costs	1,169		4,938
Other restructuring costs
Restructuring Cost and Reserve [Line Items]
Restructuring costs	$ 675		$ 3,820

GOODWILL (Details)

GOODWILL (Details) - USD ($) $ in Thousands	3 Months Ended			9 Months Ended
	Oct. 03, 2020	Apr. 04, 2020	Sep. 28, 2019	Oct. 03, 2020	Sep. 28, 2019
Goodwill [Roll Forward]
Beginning balance		$ 1,669,594		$ 1,669,594
Goodwill recognized from Kleary Acquisition				11,721
Impairment	$ 0		$ 0	(503,171)	$ 0
Currency translation				8,966
Purchase accounting adjustments				2,882
Ending balance	1,189,992			1,189,992
Asset impairment		3,100		4,900
Windows
Goodwill [Roll Forward]
Beginning balance		714,023		714,023
Goodwill recognized from Kleary Acquisition				0
Impairment		(321,000)		(320,990)
Currency translation				1,885
Purchase accounting adjustments				0
Ending balance	394,918			394,918
Siding
Goodwill [Roll Forward]
Beginning balance		807,280		807,280
Goodwill recognized from Kleary Acquisition				11,721
Impairment		(176,800)		(176,774)
Currency translation				7,081
Purchase accounting adjustments				2,882
Ending balance	652,190			652,190
Commercial
Goodwill [Roll Forward]
Beginning balance		148,291		148,291
Goodwill recognized from Kleary Acquisition				0
Impairment		$ (5,400)		(5,407)
Currency translation				0
Purchase accounting adjustments				0
Ending balance	$ 142,884			$ 142,884

INVENTORIES (Details)

INVENTORIES (Details) - USD ($) $ in Thousands	9 Months Ended
	Oct. 03, 2020	Dec. 31, 2019
Inventory [Line Items]
Raw materials	$ 232,627	$ 239,063
Work in process and finished goods	176,270	200,131
Total inventory	408,897	$ 439,194
Inventories
Inventory [Line Items]
Inventory purchase commitments	$ 21,200

INTANGIBLES (Details)

INTANGIBLES (Details) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Oct. 03, 2020	Dec. 31, 2019
Finite-Lived Intangible Assets [Line Items]
Cost	$ 2,002,368	$ 1,990,002
Accumulated Amortization	(379,235)	(249,302)
Net Carrying Value	$ 1,623,133	$ 1,740,700
Weighted Average
Finite-Lived Intangible Assets [Line Items]
Weighted Average Amortization Period (Years)	10 years	10 years
Trademarks/Trade names
Finite-Lived Intangible Assets [Line Items]
Cost	$ 248,021	$ 252,942
Accumulated Amortization	(51,658)	(38,010)
Net Carrying Value	$ 196,363	$ 214,932
Trademarks/Trade names | Minimum
Finite-Lived Intangible Assets [Line Items]
Weighted Average Amortization Period (Years)	5 years	5 years
Trademarks/Trade names | Maximum
Finite-Lived Intangible Assets [Line Items]
Weighted Average Amortization Period (Years)	15 years	15 years
Trademarks/Trade names | Weighted Average
Finite-Lived Intangible Assets [Line Items]
Weighted Average Amortization Period (Years)	8 years	9 years
Customer lists and relationships
Finite-Lived Intangible Assets [Line Items]
Cost	$ 1,754,347	$ 1,737,060
Accumulated Amortization	(327,577)	(211,292)
Net Carrying Value	$ 1,426,770	$ 1,525,768
Customer lists and relationships | Minimum
Finite-Lived Intangible Assets [Line Items]
Weighted Average Amortization Period (Years)	7 years	9 years
Customer lists and relationships | Maximum
Finite-Lived Intangible Assets [Line Items]
Weighted Average Amortization Period (Years)	20 years	20 years
Customer lists and relationships | Weighted Average
Finite-Lived Intangible Assets [Line Items]
Weighted Average Amortization Period (Years)	10 years	11 years

ASSETS HELD FOR SALE (Details)

ASSETS HELD FOR SALE (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
	Oct. 03, 2020	Oct. 03, 2020	Sep. 28, 2019	Dec. 31, 2019
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Assets held for sale, carrying value, current	$ 5,087	$ 5,087		$ 1,750
Real property assets, held-for-sale	800	800
Net book value of property, plant and equipment held-for-sale	635,904	635,904		$ 652,841
Assets held-for-sale, fair value	800	800
Proceeds from sale of property, plant and equipment		1,538	$ 873
Disposal Group, Disposed of by Sale, Not Discontinued Operations
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Net loss on sale of real property assets	400	400
Proceeds from sale of property, plant and equipment	1,800	1,800
Disposal Group, Disposed of by Sale, Not Discontinued Operations | Commercial
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Assets held for sale, carrying value, current	$ 4,300	$ 4,300

LEASES - Summary of Lease Costs

LEASES - Summary of Lease Costs (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Oct. 03, 2020	Sep. 28, 2019	Oct. 03, 2020	Sep. 28, 2019
Leases [Abstract]
Weighted-average remaining lease term	5 years 6 months		5 years 6 months
Weighted-average IBR	6.08%		6.08%
Fixed lease costs	$ 21,220	$ 23,903	$ 78,183	$ 77,125
Variable lease costs	$ 19,013	$ 8,654	$ 54,188	$ 27,868

LEASES - Summary of Cash Flow I

LEASES - Summary of Cash Flow Information (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Oct. 03, 2020	Sep. 28, 2019	Oct. 03, 2020	Sep. 28, 2019
Leases [Abstract]
Operating cash flows for operating leases	$ 24,853	$ 23,463	$ 80,241	$ 66,936
Right-of-use assets obtained in exchange for new operating lease liabilities	$ 2,070	$ 47,236	$ 18,940	$ 372,269

LEASES - Schedule of Future Min

LEASES - Schedule of Future Minimum Lease Payments (Details) - USD ($) $ in Thousands	Oct. 03, 2020	Dec. 31, 2019
Leases [Abstract]
2020 (excluding the nine months ended October 3, 2020)	$ 17,730
2021	82,979
2022	67,882
2023	42,451
2024	31,875
Thereafter	88,848
Total future minimum lease payments	331,765
Less: interest	51,911
Present value of future minimum lease payments	279,854
Current portion of lease liabilities	69,408	$ 72,428
Long-term portion of lease liabilities	$ 210,446	$ 243,780

SHARE-BASED COMPENSATION (Detai

SHARE-BASED COMPENSATION (Details) - USD ($)	3 Months Ended		9 Months Ended
	Oct. 03, 2020	Sep. 28, 2019	Oct. 03, 2020	Sep. 28, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock option awards, termination period from grant date			10 years
Expiration period, after termination of employment			60 days
Expiration period, after death, disability or retirement			180 days
Stock options, grants in period (in shares)			1,100,000	400,000
Stock options, grant date fair value (in USD per share)			$ 2.13	$ 1.97
Stock options exercised (in shares)			0	0
Allocated share-based compensation expense	$ 4,000,000	$ 3,100,000	$ 12,600,000	$ 10,600,000
PSUs and Performance Share Awards | Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock awards, targeted number of shares	0.00%		0.00%
PSUs and Performance Share Awards | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock awards, targeted number of shares	200.00%		200.00%
Performance Stock Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock awards, minimum service period required for vesting			50.00%
Incentive Plan | Employee stock options | Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period			3 years
Incentive Plan | Employee stock options | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period			5 years
Incentive Plan | PSUs and Performance Share Awards | Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period			3 years
Incentive Plan | Restricted Stock Units (RSUs) | Minimum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period			3 years
Incentive Plan | Restricted Stock Units (RSUs) | Maximum
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period			5 years
Key Employee Awards | PSUs and Performance Share Awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting period			3 years
Key Employee Awards | Restricted Stock Units (RSUs)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Value, restricted stock award, gross			$ 7,000,000	$ 2,800,000
Shares, restricted stock award, gross (in shares)			1,400,000	500,000
Key Employee Awards | Performance Stock Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Stock award grants, fair value			$ 5,600,000	$ 400,000

EARNINGS PER COMMON SHARE (Deta

EARNINGS PER COMMON SHARE (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Oct. 03, 2020	Sep. 28, 2019	Oct. 03, 2020	Sep. 28, 2019
Numerator for Basic and Diluted Earnings Per Common Share
Net income (loss) applicable to common shares	$ 30,028	$ 24,790	$ (484,658)	$ (17,320)
Denominator for Basic and Diluted Earnings Per Common Share
Weighted average basic number of common shares outstanding (in shares)	125,100	125,557	125,655	125,526
Weighted average diluted number of common shares outstanding (in shares)	125,289	125,558	125,655	125,526
Basic income (loss) per common share (in USD per share)	$ 0.24	$ 0.20	$ (3.86)	$ (0.14)
Diluted income (loss) per common share (in USD per share)	$ 0.24	$ 0.20	$ (3.86)	$ (0.14)
Incentive Plan securities excluded from dilution (in shares)	2,146	5,189	3,338	4,974
Employee stock options
Denominator for Basic and Diluted Earnings Per Common Share
Common stock equivalents (in shares)	189	1	0	0
PSUs and Performance Share Awards
Denominator for Basic and Diluted Earnings Per Common Share
Common stock equivalents (in shares)	0	0	0	0

WARRANTY (Details)

WARRANTY (Details) - USD ($) $ in Thousands	9 Months Ended
	Oct. 03, 2020	Sep. 28, 2019
Movement in Standard Product Warranty Accrual [Roll Forward]
Beginning balance	$ 216,173	$ 134,515
Acquisition	109	0
Purchase accounting adjustments	0	84,280
Warranties sold	1,885	2,313
Revenue recognized	(2,054)	(2,075)
Expense	23,257	22,006
Settlements	(22,645)	(22,285)
Ending balance	216,725	218,754
Less: current portion	27,201	31,294
Total, less current portion	$ 189,524	$ 187,460

DEFINED BENEFIT PLANS - Narrati

DEFINED BENEFIT PLANS - Narrative (Details) $ in Millions	9 Months Ended
	Oct. 03, 2020USD ($)
Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, expected contribution amount	$ 4.4
Other Postretirement Benefit Plan
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, expected contribution amount	$ 0.8
Defined benefit plan, minimum annual contribution, percent	0.00%
Defined contribution plan, maximum annual contributions per employee, percent	25.00%
The Steelworkers Pension Trust | Pension Plan | CENTRIA Benefit Plan | Minimum
Defined Benefit Plan Disclosure [Line Items]
Multiemployer plan, minimum contribution	$ 0.3

DEFINED BENEFIT PLANS - Periodi

DEFINED BENEFIT PLANS - Periodic Benefits Cost (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Oct. 03, 2020	Sep. 28, 2019	Oct. 03, 2020	Sep. 28, 2019
Pension Plan
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 11	$ 11	$ 34	$ 32
Interest cost	802	974	2,405	2,922
Expected return on assets	(1,398)	(1,234)	(4,193)	(3,701)
Amortization of prior service cost	16	15	47	43
Amortization of net actuarial loss	753	704	2,256	2,112
Net periodic benefit cost	184	470	549	1,408
Other Postretirement Benefit Plan
Defined Benefit Plan Disclosure [Line Items]
Service cost	4	6	13	17
Interest cost	59	66	178	197
Amortization of net actuarial loss	27	0	81	0
Net periodic benefit cost	$ 90	$ 72	$ 272	$ 214

LONG-TERM DEBT - Schedule of De

LONG-TERM DEBT - Schedule of Debt (Details) - USD ($) $ in Thousands	Oct. 03, 2020	Sep. 24, 2020	Dec. 31, 2019	Nov. 16, 2018	Apr. 12, 2018
Debt Instrument [Line Items]
Unamortized discounts and unamortized deferred financing costs	$ (56,470)		$ (56,063)
Total long-term debt, net of unamortized discounts and unamortized deferred financing costs	3,592,902		3,182,524
Less: current portion of long-term debt	25,600		25,600
Total long-term debt, less current portion	$ 3,567,302		3,156,924
Debt instrument, interest rate, stated percentage	6.125%
Asset-based revolving credit facility due April 2023
Debt Instrument [Line Items]
Long-term debt, gross	$ 0		70,000
Term loan facility due April 2025
Debt Instrument [Line Items]
Long-term debt, gross	2,504,372		2,523,587
Cash flow revolver due April 2023
Debt Instrument [Line Items]
Long-term debt, gross	0		0
8.00% senior notes due April 2026
Debt Instrument [Line Items]
Long-term debt, gross	645,000		645,000
Total long-term debt, net of unamortized discounts and unamortized deferred financing costs	$ 645,000		$ 645,000
Debt instrument, interest rate, stated percentage	8.00%		8.00%	8.00%	8.00%
6.125% senior notes due January 2029
Debt Instrument [Line Items]
Long-term debt, gross	$ 500,000		$ 0
Total long-term debt, net of unamortized discounts and unamortized deferred financing costs	$ 500,000		$ 0
Debt instrument, interest rate, stated percentage	6.125%	6.125%	6.125%
Other Assets | ABL Facility | Asset-based lending credit facility, due 2023
Debt Instrument [Line Items]
Unamortized deferred financing costs	$ 1,900		$ 2,400

LONG-TERM DEBT - Additional Inf

LONG-TERM DEBT - Additional Information (Details) - USD ($)	Sep. 24, 2020	Nov. 16, 2018	Oct. 15, 2018	Apr. 12, 2018	Oct. 03, 2020	Dec. 31, 2019	Nov. 15, 2018	Oct. 14, 2018
Line of Credit Facility [Line Items]
Debt instrument, interest rate, stated percentage					6.125%
Term Loan Facility due April 2025
Line of Credit Facility [Line Items]
Installment payment as a percentage of principal				1.00%
Debt instrument, interest rate during period					3.90%
Debt instrument, effective rate					6.51%
Mandatory prepayment, percentage of annual excess cash flow				50.00%
Debt instrument, covenant compliance, excess cash flow, minimum				$ 10,000,000
Cash Flow Revolver
Line of Credit Facility [Line Items]
Line of credit facility, maximum borrowing capacity				$ 115,000,000
Weighted average interest rate on debt					3.31%
Secured debt, percentage of capital stock held by foreign subsidiary				65.00%
Debt instrument, covenant compliance, secured leverage ratio, maximum				7.75
ABL Facility
Line of Credit Facility [Line Items]
Weighted average interest rate on debt					1.87%
Remaining borrowing capacity on line of credit					$ 570,000,000
Revolving loans outstanding					0
Line of credit outstanding					$ 36,500,000
8.00% senior notes due April 2026
Line of Credit Facility [Line Items]
Debt instrument, effective rate					8.64%
Debt instrument, interest rate, stated percentage		8.00%		8.00%	8.00%	8.00%
8.00% senior notes due April 2026 | Prior to April 15, 2021, 100% redemption
Line of Credit Facility [Line Items]
Debt instrument, redemption price, percentage		100.00%
8.00% senior notes due April 2026 | Prior to April 15 ,2021, 40% redemption
Line of Credit Facility [Line Items]
Debt instrument, redemption price, percentage		108.00%
Debt instrument, redemption price, percentage of principal amount redeemed		40.00%
8.00% senior notes due April 2026 | On or after April 15, 2021
Line of Credit Facility [Line Items]
Debt instrument, redemption price, percentage		104.00%
8.00% senior notes due April 2026 | On or after April 15, 2023
Line of Credit Facility [Line Items]
Debt instrument, redemption price, percentage		100.00%
6.125% senior notes due January 2029
Line of Credit Facility [Line Items]
Debt instrument, face amount	$ 500,000,000
Debt instrument, discount rate	6.125%
Debt instrument, interest rate, stated percentage	6.125%				6.125%	6.125%
6.125% senior notes due January 2029 | Prior to September 15, 2023
Line of Credit Facility [Line Items]
Debt instrument, redemption price, percentage	100.00%
6.125% senior notes due January 2029 | Prior to September 15, 2023
Line of Credit Facility [Line Items]
Debt instrument, redemption price, percentage	106.125%
Debt instrument, redemption price, percentage of principal amount redeemed	40.00%
6.125% senior notes due January 2029 | On or after September 15, 2023 and prior to September 15, 2024
Line of Credit Facility [Line Items]
Debt instrument, redemption price, percentage	103.063%
6.125% senior notes due January 2029 | On or after September 15, 2024 and prior to September 15, 2025
Line of Credit Facility [Line Items]
Debt instrument, redemption price, percentage	101.531%
6.125% senior notes due January 2029 | On or after September 15, 2025
Line of Credit Facility [Line Items]
Debt instrument, redemption price, percentage	100.00%
ABL Facility | Revolving Credit Facility
Line of Credit Facility [Line Items]
Line of credit facility, maximum borrowing capacity		$ 611,000,000	$ 396,000,000	$ 360,000,000
Increase in borrowing capacity		215,000,000	36,000,000
Payment on outstanding borrowings		325,000,000
Fixed charge coverage ratio				1
Debt instrument, covenant compliance, percentage of specified availability				10.00%
Debt instrument, covenant terms, specific availability In excess of threshold of calendar days				20 days
ABL Facility | Revolving Credit Facility | ABL U.S. Facility
Line of Credit Facility [Line Items]
Line of credit facility, maximum borrowing capacity		483,700,000	313,500,000	$ 285,000,000			$ 313,500,000	$ 285,000,000
ABL Facility | Revolving Credit Facility | ABL Canadian Facility
Line of Credit Facility [Line Items]
Line of credit facility, maximum borrowing capacity		127,300,000	$ 82,500,000	$ 75,000,000			$ 82,500,000	$ 75,000,000
London Interbank Offered Rate (LIBOR) | Term Loan Facility due April 2025
Line of Credit Facility [Line Items]
Debt instrument, basis spread on variable rate, floor				0.00%
Debt instrument, basis spread on variable rate				3.75%
London Interbank Offered Rate (LIBOR) | Cash Flow Revolver
Line of Credit Facility [Line Items]
Debt instrument, basis spread on variable rate, floor				0.00%
London Interbank Offered Rate (LIBOR) | ABL Facility
Line of Credit Facility [Line Items]
Debt instrument, basis spread on variable rate, floor				0.00%
Base Rate | Term Loan Facility due April 2025
Line of Credit Facility [Line Items]
Debt instrument, basis spread on variable rate				2.75%
Minimum | Cash Flow Revolver | Commitment Fee Percentage One
Line of Credit Facility [Line Items]
Unused commitment fee				0.25%
Minimum | ABL Facility | Commitment Fee Percentage One
Line of Credit Facility [Line Items]
Unused commitment fee				0.25%
Minimum | London Interbank Offered Rate (LIBOR) | Cash Flow Revolver
Line of Credit Facility [Line Items]
Debt instrument, basis spread on variable rate				2.50%
Minimum | London Interbank Offered Rate (LIBOR) | ABL Facility
Line of Credit Facility [Line Items]
Debt instrument, basis spread on variable rate				1.25%
Minimum | Base Rate | Cash Flow Revolver
Line of Credit Facility [Line Items]
Debt instrument, basis spread on variable rate				1.50%
Minimum | Base Rate | ABL Facility
Line of Credit Facility [Line Items]
Debt instrument, basis spread on variable rate				0.25%
Maximum | Cash Flow Revolver | Commitment Fee Percentage One
Line of Credit Facility [Line Items]
Unused commitment fee				0.50%
Maximum | London Interbank Offered Rate (LIBOR) | Cash Flow Revolver
Line of Credit Facility [Line Items]
Debt instrument, basis spread on variable rate				3.00%
Maximum | London Interbank Offered Rate (LIBOR) | ABL Facility
Line of Credit Facility [Line Items]
Debt instrument, basis spread on variable rate				1.75%
Maximum | Base Rate | Cash Flow Revolver
Line of Credit Facility [Line Items]
Debt instrument, basis spread on variable rate				2.00%
Maximum | Base Rate | ABL Facility
Line of Credit Facility [Line Items]
Debt instrument, basis spread on variable rate				0.75%
Leverage Ratio Target Achieved | Minimum | Term Loan Facility due April 2025
Line of Credit Facility [Line Items]
Mandatory prepayment, percentage of annual excess cash flow				25.00%
Leverage Ratio Target Achieved | Maximum | Term Loan Facility due April 2025
Line of Credit Facility [Line Items]
Mandatory prepayment, percentage of annual excess cash flow				0.00%
Ply Gem | 8.00% senior notes due April 2026
Line of Credit Facility [Line Items]
Debt instrument, face amount				$ 645,000,000
Ply Gem | Term Loan Facility due April 2025
Line of Credit Facility [Line Items]
Debt instrument, face amount				$ 1,755,000,000
Debt instrument, discount rate				0.50%
Increase in borrowing capacity		$ 805,000,000
Ply Gem | 8.00% senior notes due April 2026
Line of Credit Facility [Line Items]
Debt instrument, discount rate				2.25%

CD&R INVESTOR GROUP (Details)

CD&R INVESTOR GROUP (Details)	Oct. 03, 2020	Dec. 31, 2019
CD&R Funds
Class of Stock [Line Items]
Ownership percentage	49.50%	49.10%

STOCK REPURCHASE PROGRAM (Detai

STOCK REPURCHASE PROGRAM (Details) - USD ($)	3 Months Ended		9 Months Ended
	Oct. 03, 2020	Sep. 28, 2019	Oct. 03, 2020	Sep. 28, 2019	Mar. 07, 2018	Oct. 10, 2017
Class of Stock [Line Items]
Purchases of treasury stock			$ 6,428,000	$ 0
Available for stock repurchases	$ 49,100,000		$ 49,100,000
Shares withheld to satisfy minimum tax withholding obligations (in shares)			100,000	35,000
Retirement of treasury stock previously withheld or repurchased (in shares)			1,200,000	100,000
2017 Stock Repurchase Program
Class of Stock [Line Items]
Authorized stock repurchase amount						$ 50,000,000
2018 Stock Repurchase Program
Class of Stock [Line Items]
Authorized stock repurchase amount					$ 50,000,000
Stock Repurchase Programs
Class of Stock [Line Items]
Authorized stock repurchase amount	$ 100,000,000		$ 100,000,000
Treasury stock purchases (in shares)			1,100,000	0
Purchases of treasury stock			$ 6,400,000
Additional Paid-In Capital
Class of Stock [Line Items]
Decrease in treasury stock and additional paid in capital			$ 6,900,000	$ 700,000
Treasury Stock
Class of Stock [Line Items]
Treasury stock purchases (in shares)	1,635	12,612	1,168,514	34,724
Decrease in treasury stock and additional paid in capital			$ 6,900,000	$ 700,000

FAIR VALUE OF FINANCIAL INSTR_3

FAIR VALUE OF FINANCIAL INSTRUMENTS AND FAIR VALUE MEASUREMENTS - Schedule of Fair Values of Financial Instruments (Details) - USD ($)	Oct. 03, 2020	Sep. 24, 2020	Dec. 31, 2019	Nov. 16, 2018	Apr. 12, 2018
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Carrying Amount	$ 3,592,902,000		$ 3,182,524,000
Debt instrument, interest rate, stated percentage	6.125%
8.00% senior notes due April 2026
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Carrying Amount	$ 645,000,000		645,000,000
Fair Value	$ 675,638,000		$ 670,800,000
Debt instrument, interest rate, stated percentage	8.00%		8.00%	8.00%	8.00%
6.125% senior notes due January 2029
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Carrying Amount	$ 500,000,000		$ 0
Fair Value	$ 505,000,000		$ 0
Debt instrument, interest rate, stated percentage	6.125%	6.125%	6.125%
ABL Facility
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Carrying Amount	$ 0
Cash Flow Revolver
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Carrying Amount	0
Term Loan Facility
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Carrying Amount	2,504,372,000		$ 2,523,587,000
Fair Value	$ 2,479,328,000		$ 2,514,906,000

FAIR VALUE OF FINANCIAL INSTR_4

FAIR VALUE OF FINANCIAL INSTRUMENTS AND FAIR VALUE MEASUREMENTS - Fair Value by Level (Details) $ in Thousands	1 Months Ended	3 Months Ended	9 Months Ended
	May 31, 2019USD ($)instrument	Sep. 28, 2019USD ($)	Oct. 03, 2020USD ($)	Sep. 28, 2019USD ($)	Dec. 31, 2019USD ($)
Assets:
Short-term investments in deferred compensation plan			$ 1,917		$ 3,776
Total assets			1,917		3,776
Liabilities:
Fair value of liabilities			85,458		33,835
Short-term investments, unrealized holding gain (loss)		$ (100)	(700)	$ 400
Level 1
Assets:
Short-term investments in deferred compensation plan			1,766		3,387
Total assets			1,766		3,387
Liabilities:
Fair value of liabilities			0		0
Level 2
Assets:
Short-term investments in deferred compensation plan			151		389
Total assets			151		389
Liabilities:
Fair value of liabilities			85,458		33,835
Level 3
Assets:
Short-term investments in deferred compensation plan			0		0
Total assets			0		0
Liabilities:
Fair value of liabilities			0		0
Deferred compensation plan liability
Liabilities:
Fair value of liabilities			2,154		3,847
Deferred compensation plan liability | Level 1
Liabilities:
Fair value of liabilities			0		0
Deferred compensation plan liability | Level 2
Liabilities:
Fair value of liabilities			2,154		3,847
Deferred compensation plan liability | Level 3
Liabilities:
Fair value of liabilities			0		0
Interest Rate Swap
Liabilities:
Fair value of liabilities			83,304		29,988
Interest Rate Swap | Level 1
Liabilities:
Fair value of liabilities			0		0
Interest Rate Swap | Level 2
Liabilities:
Fair value of liabilities			83,304		29,988
Interest Rate Swap | Level 3
Liabilities:
Fair value of liabilities			0		0
Money market
Assets:
Short-term investments in deferred compensation plan			197		2
Money market | Level 1
Assets:
Short-term investments in deferred compensation plan			197		2
Money market | Level 2
Assets:
Short-term investments in deferred compensation plan			0		0
Money market | Level 3
Assets:
Short-term investments in deferred compensation plan			0		0
Mutual funds – Growth
Assets:
Short-term investments in deferred compensation plan			397		1,044
Mutual funds – Growth | Level 1
Assets:
Short-term investments in deferred compensation plan			397		1,044
Mutual funds – Growth | Level 2
Assets:
Short-term investments in deferred compensation plan			0		0
Mutual funds – Growth | Level 3
Assets:
Short-term investments in deferred compensation plan			0		0
Mutual funds – Blend
Assets:
Short-term investments in deferred compensation plan			890		1,769
Mutual funds – Blend | Level 1
Assets:
Short-term investments in deferred compensation plan			890		1,769
Mutual funds – Blend | Level 2
Assets:
Short-term investments in deferred compensation plan			0		0
Mutual funds – Blend | Level 3
Assets:
Short-term investments in deferred compensation plan			0		0
Mutual funds – Foreign blend
Assets:
Short-term investments in deferred compensation plan			282		572
Mutual funds – Foreign blend | Level 1
Assets:
Short-term investments in deferred compensation plan			282		572
Mutual funds – Foreign blend | Level 2
Assets:
Short-term investments in deferred compensation plan			0		0
Mutual funds – Foreign blend | Level 3
Assets:
Short-term investments in deferred compensation plan			0		0
Mutual funds – Fixed income
Assets:
Short-term investments in deferred compensation plan			151		389
Mutual funds – Fixed income | Level 1
Assets:
Short-term investments in deferred compensation plan			0		0
Mutual funds – Fixed income | Level 2
Assets:
Short-term investments in deferred compensation plan			151		389
Mutual funds – Fixed income | Level 3
Assets:
Short-term investments in deferred compensation plan			$ 0		$ 0
Designated as Hedging Instrument | Interest Rate Swap
Liabilities:
Derivative, term of contract	4 years
Derivative, notional amount	$ 1,500,000
Cash Flow Hedging | Designated as Hedging Instrument | Interest Rate Swap
Liabilities:
Number of interest rate swaps | instrument	3
Cash Flow Hedging | Designated as Hedging Instrument | Interest Rate Swap One
Liabilities:
Derivative, notional amount	$ 500,000
Derivative, fixed interest rate	5.918%
Cash Flow Hedging | Designated as Hedging Instrument | Interest Rate Swap Two
Liabilities:
Derivative, notional amount	$ 500,000
Derivative, fixed interest rate	5.906%
Cash Flow Hedging | Designated as Hedging Instrument | Interest Rate Swap Three
Liabilities:
Derivative, notional amount	$ 500,000
Derivative, fixed interest rate	5.907%

INCOME TAXES - Narrative (Detai

INCOME TAXES - Narrative (Details) $ in Millions	9 Months Ended
	Oct. 03, 2020USD ($)
Income Tax Disclosure [Abstract]
Estimated effective tax rate (as a percent)	40.00%
Effective tax rate (as a percent)	2.50%
Valuation allowance	$ 11.3
Increase in tax reserves	0.6
Liability for unrecognized tax benefits	$ 12.5

SEGMENT INFORMATION (Details)

SEGMENT INFORMATION (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Oct. 03, 2020USD ($)	Sep. 28, 2019USD ($)	Oct. 03, 2020USD ($)reporting_segment	Sep. 28, 2019USD ($)	Dec. 31, 2019USD ($)
Segment Reporting Information [Line Items]
Number of reportable segments | reporting_segment			3
Total net sales	$ 1,227,253	$ 1,285,043	$ 3,426,000	$ 3,645,332
Total operating income (loss)	103,979	95,560	(337,887)	149,126
Unallocated other expense, net	(50,402)	(56,293)	(159,056)	(170,894)
Income (loss) before income taxes	53,577	39,267	(496,943)	(21,768)
Total assets	5,474,981		5,474,981		$ 5,564,346
Windows
Segment Reporting Information [Line Items]
Total net sales	501,314	504,338	1,378,039	1,434,579
Siding
Segment Reporting Information [Line Items]
Total net sales	321,898	315,799	848,190	840,601
Commercial
Segment Reporting Information [Line Items]
Total net sales	404,041	464,906	1,199,771	1,370,152
Operating Segments | Windows
Segment Reporting Information [Line Items]
Total net sales	501,314	504,338	1,378,039	1,434,579
Total operating income (loss)	37,295	34,446	(252,794)	62,039
Total assets	1,820,255		1,820,255		2,166,220
Operating Segments | Siding
Segment Reporting Information [Line Items]
Total net sales	321,898	315,799	848,190	840,601
Total operating income (loss)	45,313	37,063	(92,916)	51,346
Total assets	2,158,395		2,158,395		2,289,310
Operating Segments | Commercial
Segment Reporting Information [Line Items]
Total net sales	404,041	464,906	1,199,771	1,370,152
Total operating income (loss)	56,137	59,317	109,642	142,436
Total assets	878,623		878,623		963,291
Corporate
Segment Reporting Information [Line Items]
Total operating income (loss)	(34,766)	$ (35,266)	(101,819)	$ (106,695)
Total assets	$ 617,708		$ 617,708		$ 145,525

CONTINGENCIES (Details)

CONTINGENCIES (Details) $ in Millions	Apr. 11, 2019defendant	Oct. 03, 2020USD ($)
Recovery From Countervailing Duty Tariff Proceedings
Loss Contingencies [Line Items]
Amount sought by company		$ 4.1
Countervailing Duty Tariff Proceedings
Loss Contingencies [Line Items]
Tariff rate for imports (as a percent)		0.00%
Antidumping Tariff Proceedings
Loss Contingencies [Line Items]
Tariff rate for imports (as a percent)		8.47%
RCRA Facility Investigation
Loss Contingencies [Line Items]
Liability accrual		$ 4.5
PCE/TCE Northeast Contamination Site
Loss Contingencies [Line Items]
Liability accrual		4.6
Aurora Plastics LLC vs. Atrium
Loss Contingencies [Line Items]
Liability accrual		7.6
Voigt Vs. C D R Case
Loss Contingencies [Line Items]
Number of defendants | defendant	12
Current Liabilities | RCRA Facility Investigation
Loss Contingencies [Line Items]
Liability accrual		1
Other Noncurrent Liabilities | RCRA Facility Investigation
Loss Contingencies [Line Items]
Liability accrual		3.5
Other Current Liabilities | Aurora Plastics LLC vs. Atrium
Loss Contingencies [Line Items]
Liability accrual		$ 3.6