Business and Basis of Presentation	6 Months Ended
Jun. 30, 2021
Accounting Policies [Abstract]
Business and Basis of Presentation	NOTE 1. BUSINESS AND BASIS OF PRESENTATION Armstrong World Industries, Inc. (“AWI”) is a Pennsylvania corporation incorporated in 1891. When we refer to “AWI,” the “Company,” “we,” “our” or “us” in these notes, we are referring to AWI and its subsidiaries. Except as disclosed in this Note, the accounting policies used in preparing the Condensed Consolidated Financial Statements in this Form 10-Q are the same as those used in preparing the Consolidated Financial Statements for the year ended December 31, 2020. These statements should therefore be read in conjunction with the Consolidated Financial Statements and notes that are included in the Annual Report on Form 10-K for the fiscal year ended December 31, 2020. In the opinion of management, all adjustments of a normal recurring nature have been included to provide a fair statement of the results for the reporting periods presented. Operating results for the second quarter and first six months of 2021 and 2020 included in this report are unaudited. Quarterly results are not necessarily indicative of annual earnings, primarily due to the different level of sales in each quarter of the year and the possibility of changes in general economic conditions. These Condensed Consolidated Financial Statements are prepared in accordance with U.S. generally accepted accounting principles (“U.S. GAAP”). The statements include management estimates and judgments, where appropriate. Management utilizes estimates to record many items, including certain asset values, contingent purchase price liabilities, allowances for bad debts, inventory obsolescence and lower of cost and net realizable value charges, warranty reserves, workers’ compensation, general liability and environmental claims, and income taxes. When preparing an estimate, management determines the amount based upon the consideration of relevant information and may confer with outside parties, including external counsel. Actual results may differ from these estimates. Certain prior year amounts have been reclassified in the Condensed Consolidated Financial Statements to conform to the 2021 presentation. Acquisitions In December 2020, we acquired all of the issued and outstanding equity of Arktura LLC (“Arktura”) and certain subsidiaries with operations in the United States and Argentina. Arktura is a designer and fabricator of metal and felt ceilings, walls, partitions, and facades with one manufacturing facility based in Los Angeles, California. In August 2020, we acquired the business and assets of Moz Designs, Inc. (“Moz”), based in Oakland, California. Moz is a designer and fabricator of custom architectural metal ceilings, walls, dividers and column covers for interior and exterior applications with one manufacturing facility. In July 2020, we acquired all the issued and outstanding capital stock of TURF Design, Inc. (“Turf”), with one manufacturing facility in Elgin, Illinois and a design center in Chicago, Illinois. Turf is a designer and manufacturer of acoustic felt ceilings and wall products. The operations, assets and liabilities of these acquisitions are included in our Architectural Specialties segment. See Note 4 for further information on our recent acquisitions. Discontinued Operations In 2019, we completed the sale of certain subsidiaries comprising our businesses and operations in Europe, the Middle East and Africa (including Russia) (“EMEA”) and the Pacific Rim, including the corresponding businesses and operations conducted by Worthington Armstrong Venture (“WAVE”), our joint venture with Worthington Industries, Inc. (“Worthington”) in which AWI holds a 50% interest (collectively, the “Sale”), to Knauf International GmbH (“Knauf”). In January 2021, we finalized the post-closing adjustments to purchase price related to certain pension liabilities assumed by Knauf in the Sale. During the first quarter of 2021, we paid $11.8 million to Knauf related to this purchase price adjustment. See Note 5 for additional information related to our discontinued operations. Recently Adopted Accounting Standards In December 2019, the FASB issued ASU 2019-12, “Simplifying the Accounting for Income Taxes,” which removes exceptions to the general principles in ASC Topic 740 – Income Taxes for allocating tax expense between financial statement components, accounting basis differences resulting from an ownership change in foreign investments and interim period income tax accounting for year-to-date losses that exceed projected losses. Effective January 1, 2021, we adopted this standard, which had no material impact on our financial condition or results of operations. COVID-19 Considerations The COVID-19 pandemic has created significant volatility and economic disruption and the impact on our future consolidated results of operations is uncertain. The extent to which COVID-19 impacts our employees, operations, customers, suppliers and financial results depends on numerous evolving factors that we are not be able to accurately predict, including: the duration and scope of the pandemic; government actions taken in response to the pandemic; the availability and distribution of vaccines; the impact on construction activity; the effect on our customers demand for our ceiling and wall systems; our ability to manufacture and sell our products; and the ability of our customers to pay for our products. While many of our products support life sustaining activities and essential construction, we, and certain of our customers or suppliers, may be impacted by state actions, orders and policies regarding the COVID-19 pandemic, including temporary closures of non-life sustaining businesses, shelter-in-place orders, and travel, social distancing and quarantine policies, the implementation and enforcement of which vary by individual U.S. states and by individual countries in the Americas. We did not record any asset impairments, inventory charges or material bad debt reserves related to COVID-19 during the second quarter and first six months of 2021 and 2020 but future events may require such charges, which could have a material adverse effect on our financial condition, liquidity or results of operations.

Business and Basis of Presentation

6 Months Ended

Jun. 30, 2021

NOTE 1. BUSINESS AND BASIS OF PRESENTATION

Armstrong World Industries, Inc. (“AWI”) is a Pennsylvania corporation incorporated in 1891. When we refer to “AWI,” the “Company,” “we,” “our” or “us” in these notes, we are referring to AWI and its subsidiaries.

Except as disclosed in this Note, the accounting policies used in preparing the Condensed Consolidated Financial Statements in this Form 10-Q are the same as those used in preparing the Consolidated Financial Statements for the year ended December 31, 2020. These statements should therefore be read in conjunction with the Consolidated Financial Statements and notes that are included in the Annual Report on Form 10-K for the fiscal year ended December 31, 2020. In the opinion of management, all adjustments of a normal recurring nature have been included to provide a fair statement of the results for the reporting periods presented. Operating results for the second quarter and first six months of 2021 and 2020 included in this report are unaudited. Quarterly results are not necessarily indicative of annual earnings, primarily due to the different level of sales in each quarter of the year and the possibility of changes in general economic conditions.

These Condensed Consolidated Financial Statements are prepared in accordance with U.S. generally accepted accounting principles (“U.S. GAAP”). The statements include management estimates and judgments, where appropriate. Management utilizes estimates to record many items, including certain asset values, contingent purchase price liabilities, allowances for bad debts, inventory obsolescence and lower of cost and net realizable value charges, warranty reserves, workers’ compensation, general liability and environmental claims, and income taxes. When preparing an estimate, management determines the amount based upon the consideration of relevant information and may confer with outside parties, including external counsel. Actual results may differ from these estimates.

Certain prior year amounts have been reclassified in the Condensed Consolidated Financial Statements to conform to the 2021 presentation.

Acquisitions

In December 2020, we acquired all of the issued and outstanding equity of Arktura LLC (“Arktura”) and certain subsidiaries with operations in the United States and Argentina. Arktura is a designer and fabricator of metal and felt ceilings, walls, partitions, and facades with one manufacturing facility based in Los Angeles, California.

In August 2020, we acquired the business and assets of Moz Designs, Inc. (“Moz”), based in Oakland, California. Moz is a designer and fabricator of custom architectural metal ceilings, walls, dividers and column covers for interior and exterior applications with one manufacturing facility.

In July 2020, we acquired all the issued and outstanding capital stock of TURF Design, Inc. (“Turf”), with one manufacturing facility in Elgin, Illinois and a design center in Chicago, Illinois. Turf is a designer and manufacturer of acoustic felt ceilings and wall products.

The operations, assets and liabilities of these acquisitions are included in our Architectural Specialties segment. See Note 4 for further information on our recent acquisitions.

Discontinued Operations

In 2019, we completed the sale of certain subsidiaries comprising our businesses and operations in Europe, the Middle East and Africa (including Russia) (“EMEA”) and the Pacific Rim, including the corresponding businesses and operations conducted by Worthington Armstrong Venture (“WAVE”), our joint venture with Worthington Industries, Inc. (“Worthington”) in which AWI holds a 50% interest (collectively, the “Sale”), to Knauf International GmbH (“Knauf”). In January 2021, we finalized the post-closing adjustments to purchase price related to certain pension liabilities assumed by Knauf in the Sale. During the first quarter of 2021, we paid $11.8 million to Knauf related to this purchase price adjustment.

See Note 5 for additional information related to our discontinued operations.

Recently Adopted Accounting Standards

In December 2019, the FASB issued ASU 2019-12, “Simplifying the Accounting for Income Taxes,” which removes exceptions to the general principles in ASC Topic 740 – Income Taxes for allocating tax expense between financial statement components, accounting

basis differences resulting from an ownership change in foreign investments and interim period income tax accounting for year-to-date losses that exceed projected losses. Effective January 1, 2021, we adopted this standard, which had no material impact on our financial condition or results of operations.

COVID-19 Considerations

The COVID-19 pandemic has created significant volatility and economic disruption and the impact on our future consolidated results of operations is uncertain. The extent to which COVID-19 impacts our employees, operations, customers, suppliers and financial results depends on numerous evolving factors that we are not be able to accurately predict, including: the duration and scope of the pandemic; government actions taken in response to the pandemic; the availability and distribution of vaccines; the impact on construction activity; the effect on our customers demand for our ceiling and wall systems; our ability to manufacture and sell our products; and the ability of our customers to pay for our products. While many of our products support life sustaining activities and essential construction, we, and certain of our customers or suppliers, may be impacted by state actions, orders and policies regarding the COVID-19 pandemic, including temporary closures of non-life sustaining businesses, shelter-in-place orders, and travel, social distancing and quarantine policies, the implementation and enforcement of which vary by individual U.S. states and by individual countries in the Americas. We did not record any asset impairments, inventory charges or material bad debt reserves related to COVID-19 during the second quarter and first six months of 2021 and 2020 but future events may require such charges, which could have a material adverse effect on our financial condition, liquidity or results of operations.