Basis of Presentation	6 Months Ended
Jun. 30, 2019
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Basis of Presentation	1. Basis of Presentation Builders FirstSource, Inc., a Delaware corporation formed in 1998, is a leading supplier and manufacturer of building materials, manufactured components and construction services to professional homebuilders, sub-contractors, remodelers and consumers. The Company operates 400 locations in 39 states across the United States. In this quarterly report, references to the “Company,” “we,” “our,” “ours” or “us” refer to Builders FirstSource, Inc. and its consolidated subsidiaries unless otherwise stated or the context otherwise requires. In the opinion of management, the accompanying unaudited condensed consolidated financial statements include all recurring adjustments and normal accruals necessary for a fair statement of the Company’s financial position, results of operations and cash flows for the dates and periods presented. Results for interim periods are not necessarily indicative of the results to be expected during the remainder of the current year or for any future period. Intercompany transactions are eliminated in consolidation. The condensed consolidated balance sheet as of December 31, 2018 is derived from the audited consolidated financial statements but does not include all disclosures required by accounting principles generally accepted in the United States of America. This condensed consolidated balance sheet as of December 31, 2018 and the unaudited condensed consolidated financial statements included herein should be read in conjunction with the more detailed audited consolidated financial statements for the year ended December 31, 2018 included in our most recent annual report on Form 10-K. Accounting policies used in the preparation of these unaudited condensed consolidated financial statements are consistent with the accounting policies described in the Notes to Consolidated Financial Statements included in our Form 10-K, except as noted below relating to the adoption of updated guidance under the Leases topic of the Accounting Standards Codification (“Codification”). Recent Accounting Pronouncements In June 2016, the FASB issued an update to existing guidance under the Investments topic of the Codification. This update introduces a new impairment model for financial assets, known as the current expected credit losses (“CECL”) model that is based on expected losses rather than incurred losses. The CECL model requires an entity to estimate credit losses on financial assets, including trade accounts receivable, based on historical information, current information and reasonable and supportable forecasts. Under this guidance companies will record an allowance through earnings for expected credit losses upon initial recognition of the financial asset. The aspects of this guidance applicable to us will be required to be adopted on a modified retrospective basis. This update is effective for public companies for annual and interim periods beginning after December 15, 2019, with early adoption permitted for annual and interim periods beginning after December 15, 2018. While we are still evaluating the impact of this guidance on our financial statements, we do not currently expect it to have a material impact. In February 2016, the FASB issued an update to the existing guidance under the Leases topic of the Codification. Under the new guidance, lessees are now required to recognize the following for all leases, with the exception of short-term leases, at the commencement date: (1) a lease liability, which is a lessee’s obligation to make lease payments arising from a lease, measured on a discounted basis; and (2) a right-of-use asset, which is an asset that represents the lessee’s right to use, or control the use of, a specified asset for the lease term. We adopted this guidance on January 1, 2019 by applying the provisions of this guidance on a modified retrospective basis as of the effective date. As such, comparative periods have not been restated and the disclosures required under the new standard have not been provided for periods prior to January 1, 2019. We elected the package of practical expedients whereby we were not required to: i) reassess whether any expired or existing contracts are or contain leases, ii) reassess the lease classification of existing leases and iii) reassess initial direct costs for any existing leases. We did not elect the hindsight practical expedient or the practical expedient related to land easements. We have assessed and updated our business processes, systems and controls to ensure compliance with the recognition and disclosure requirements of the new standard. Adoption of the new standard resulted in the recording of right-of-use assets and lease liabilities of $269.7 million and $267.5 million, respectively, as of January 1, 2019 to recognize operating leases, primarily related to real estate and rolling stock, which were not recognized on our balance sheet under previous guidance. Further, the adoption of this guidance had no impact to our remaining other finance obligations as they continue to fail to meet the sale-leaseback requirements of the new standard. The adoption of this guidance did not have a material impact on our condensed consolidated statement of operations and comprehensive income or on our condensed consolidated statement of cash flows as our leases retained their classifications as determined under previous guidance.

Basis of Presentation

6 Months Ended

Jun. 30, 2019

Organization Consolidation And Presentation Of Financial Statements [Abstract]

1. Basis of Presentation

Builders FirstSource, Inc., a Delaware corporation formed in 1998, is a leading supplier and manufacturer of building materials, manufactured components and construction services to professional homebuilders, sub-contractors, remodelers and consumers. The Company operates 400 locations in 39 states across the United States. In this quarterly report, references to the “Company,” “we,” “our,” “ours” or “us” refer to Builders FirstSource, Inc. and its consolidated subsidiaries unless otherwise stated or the context otherwise requires.

In the opinion of management, the accompanying unaudited condensed consolidated financial statements include all recurring adjustments and normal accruals necessary for a fair statement of the Company’s financial position, results of operations and cash flows for the dates and periods presented. Results for interim periods are not necessarily indicative of the results to be expected during the remainder of the current year or for any future period. Intercompany transactions are eliminated in consolidation.

The condensed consolidated balance sheet as of December 31, 2018 is derived from the audited consolidated financial statements but does not include all disclosures required by accounting principles generally accepted in the United States of America. This condensed consolidated balance sheet as of December 31, 2018 and the unaudited condensed consolidated financial statements included herein should be read in conjunction with the more detailed audited consolidated financial statements for the year ended December 31, 2018 included in our most recent annual report on Form 10-K. Accounting policies used in the preparation of these unaudited condensed consolidated financial statements are consistent with the accounting policies described in the Notes to Consolidated Financial Statements included in our Form 10-K, except as noted below relating to the adoption of updated guidance under the Leases topic of the Accounting Standards Codification (“Codification”).

Recent Accounting Pronouncements

In June 2016, the FASB issued an update to existing guidance under the Investments topic of the Codification. This update introduces a new impairment model for financial assets, known as the current expected credit losses (“CECL”) model that is based on expected losses rather than incurred losses. The CECL model requires an entity to estimate credit losses on financial assets, including trade accounts receivable, based on historical information, current information and reasonable and supportable forecasts. Under this guidance companies will record an allowance through earnings for expected credit losses upon initial recognition of the financial asset. The aspects of this guidance applicable to us will be required to be adopted on a modified retrospective basis. This update is effective for public companies for annual and interim periods beginning after December 15, 2019, with early adoption permitted for annual and interim periods beginning after December 15, 2018. While we are still evaluating the impact of this guidance on our financial statements, we do not currently expect it to have a material impact.

In February 2016, the FASB issued an update to the existing guidance under the Leases topic of the Codification. Under the new guidance, lessees are now required to recognize the following for all leases, with the exception of short-term leases, at the commencement date: (1) a lease liability, which is a lessee’s obligation to make lease payments arising from a lease, measured on a discounted basis; and (2) a right-of-use asset, which is an asset that represents the lessee’s right to use, or control the use of, a specified asset for the lease term.

We adopted this guidance on January 1, 2019 by applying the provisions of this guidance on a modified retrospective basis as of the effective date. As such, comparative periods have not been restated and the disclosures required under the new standard have not been provided for periods prior to January 1, 2019. We elected the package of practical expedients whereby we were not required to: i) reassess whether any expired or existing contracts are or contain leases, ii) reassess the lease classification of existing leases and iii) reassess initial direct costs for any existing leases. We did not elect the hindsight practical expedient or the practical expedient related to land easements. We have assessed and updated our business processes, systems and controls to ensure compliance with the recognition and disclosure requirements of the new standard.

Adoption of the new standard resulted in the recording of right-of-use assets and lease liabilities of $269.7 million and $267.5 million, respectively, as of January 1, 2019 to recognize operating leases, primarily related to real estate and rolling stock, which were not recognized on our balance sheet under previous guidance. Further, the adoption of this guidance had no impact to our remaining other finance obligations as they continue to fail to meet the sale-leaseback requirements of the new standard. The adoption of this guidance did not have a material impact on our condensed consolidated statement of operations and comprehensive income or on our condensed consolidated statement of cash flows as our leases retained their classifications as determined under previous guidance.