Business	12 Months Ended
Dec. 31, 2017
Business [Abstract]
Business	NOTE 1. BUSINESS Armstrong World Industries, Inc. (“AWI”) is a Pennsylvania corporation incorporated in 1891. When we refer to “AWI,” the “Company,” “we,” “our” and “us” in these notes, we are referring to AWI and its subsidiaries. On November 17, 2017, we entered into a Share Purchase Agreement (the “Purchase Agreement”) with Knauf International GmbH (“Knauf”), to sell certain subsidiaries comprising our business 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., in which AWI holds a 50% interest. The total consideration to be paid by Knauf in connection with the sale is $330.0 million in cash, inclusive of amounts due to WAVE, subject to certain adjustments as provided in the Purchase Agreement, including adjustments based on the economic impact of any required regulatory remedies and a working capital adjustment. The transaction, which is subject to regulatory approvals and other customary conditions, is currently anticipated to close in mid-2018. EMEA and Pacific Rim’s historical financial results have been reflected in AWI’s Consolidated Financial Statements as discontinued operations for all periods presented. See Note 4 for additional information. In January 2017, we acquired the business and assets of Tectum, Inc. (“Tectum”), based in Newark, Ohio. Tectum is a manufacturer of acoustical ceiling, wall and structural solutions for commercial building applications with two manufacturing facilities. Tectum’s operations and its assets and liabilities have been included as a component of our Architectural Specialties segment. See Note 4 for additional information.

NOTE 1. BUSINESS

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

On November 17, 2017, we entered into a Share Purchase Agreement (the “Purchase Agreement”) with Knauf International GmbH (“Knauf”), to sell certain subsidiaries comprising our business 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., in which AWI holds a 50% interest. The total consideration to be paid by Knauf in connection with the sale is $330.0 million in cash, inclusive of amounts due to WAVE, subject to certain adjustments as provided in the Purchase Agreement, including adjustments based on the economic impact of any required regulatory remedies and a working capital adjustment. The transaction, which is subject to regulatory approvals and other customary conditions, is currently anticipated to close in mid-2018. EMEA and Pacific Rim’s historical financial results have been reflected in AWI’s Consolidated Financial Statements as discontinued operations for all periods presented. See Note 4 for additional information.

In January 2017, we acquired the business and assets of Tectum, Inc. (“Tectum”), based in Newark, Ohio. Tectum is a manufacturer of acoustical ceiling, wall and structural solutions for commercial building applications with two manufacturing facilities. Tectum’s operations and its assets and liabilities have been included as a component of our Architectural Specialties segment. See Note 4 for additional information.