Business and Basis of Presentation	3 Months Ended
Business and Basis of Presentation	Mar. 31, 2020
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Business and Basis of Presentation	Business and Basis of Presentation Business Foundation Building Materials, Inc. (the "Company") is a specialty building products distributor of wallboard, suspended ceiling systems, and metal framing throughout the U.S. and Canada. The Company is based in Santa Ana, California. Organization The Company was formed on October 27, 2016 (inception). The initial stockholder of the Company was LSF9 Cypress Parent 2 LLC ("Parent 2"), an affiliate of Lone Star Fund IX (U.S.) L.P., which we refer to with certain of its affiliates and associates (excluding us and other companies it owns as a result of its investment activities), as Lone Star. At the Company's inception, Lone Star held all of the Company's authorized, issued and outstanding shares of common stock. Principles of Consolidation The accompanying condensed consolidated financial statements include the accounts of the Company and its consolidated subsidiaries. All intercompany balances and transactions have been eliminated. Reorganization On February 8, 2017, FBM Alpha LLC (formerly known as LSF9 Cypress Parent, LLC) ("Alpha"), transferred its wholly owned direct subsidiary, Foundation Building Materials Holding Company LLC (formerly known as FBM Beta LLC and LSF9 Cypress Holdings, LLC) ("Holdco"), and indirectly held subsidiary FBM Finance, Inc., to the Company, thereby transferring the business to be indirectly held by the Company. The Company holds no other operations, cash flows, material assets or liabilities other than the equity interests in Alpha. Alpha holds no other operations, cash flows, material assets or liabilities other than the equity interests in Holdco. Holdco holds no other material assets or liabilities other than the equity interests in FBM Finance, Inc. and Foundation Building Materials, LLC. Basis of Presentation The accompanying unaudited condensed consolidated financial statements have been prepared in accordance with generally accepted accounting principles in the United States ("GAAP") for interim financial information and Article 10 of Regulation S-X. Accordingly, they do not include all the information and footnotes required by GAAP for complete financial statements. In the opinion of management, all adjustments, consisting of normal recurring adjustments necessary for a fair presentation with respect to the interim financial statements, have been included. The results of operations for interim periods are not necessarily indicative of the results for full fiscal years. For further information, refer to the consolidated financial statements and footnotes thereto for the year ended December 31, 2019, included in the Company’s Annual Report on Form 10-K filed with the Securities and Exchange Commission on February 25, 2020 (the "2019 10-K"). Reclassification to the Condensed Consolidated Statements of Cash Flows For the three months ended March 31, 2019, the Company reclassified the presentation of operating lease payments of $6.6 million, which were previously included in the change in other liabilities in the condensed consolidated statements of cash flows and are now being presented in a separate line item as a change in operating lease liabilities to conform to the current period presentation. There is no impact on the net cash provided by operating activities from continuing operations in the condensed consolidated statements of cash flows.