Basis of Presentation	6 Months Ended
Jun. 30, 2017
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 of building materials, manufactured components and construction services to professional contractors, sub-contractors, and consumers. The Company operates 400 locations in 40 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, 2016 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, 2016 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, 2016 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. Recent Accounting Pronouncements In May 2017, the Financial Accounting Standards Board (“FASB”) issued an update to the existing guidance under the Compensation-Stock Compensation topic of the Accounting Standards Codification (“Codification”) to clarify when modification accounting would be applied for a change to the terms or conditions of a share-based award. Under this new guidance modification accounting is required only if the fair value, the vesting conditions, or the classification of the award changes as a result of the change in terms or conditions. This guidance is required to be adopted on a prospective basis for annual periods beginning on or after December 15, 2017 with early adoption permitted. The Company does not regularly modify the terms and conditions of its share-based awards and does not expect the adoption of this guidance to have a significant impact on our financial statements. In January 2017, the FASB issued an update to the existing guidance under the Intangibles-Goodwill and Other topic of the Codification to simplify the accounting for goodwill impairment. The guidance removes Step 2 of the goodwill impairment test, which requires a hypothetical purchase price allocation. A goodwill impairment will now be the amount by which a reporting unit’s carrying value exceeds its fair value, not to exceed the carrying amount of goodwill. All of the other goodwill impairment guidance will remain largely unchanged, including the option to perform a qualitative assessment to determine if a quantitative impairment test is necessary. This update is effective for annual and any interim goodwill impairment tests in fiscal years beginning after December 15, 2019. Early adoption of this guidance is permitted for annual or interim goodwill tests performed after January 1, 2017. As such, the Company intends to adopt this guidance in the fourth quarter of 2017 in connection with its annual goodwill impairment test. This guidance will be applied on a prospective basis following adoption. In January 2017, the FASB issued an update to the existing guidance under the Business Combinations topic of the Codification. This update revises the definition of a business. Under this guidance when substantially all of the assets acquired are concentrated in a single asset (or group of similar assets) the assets acquired would not be considered a business. If this initial screen is met the need for further assessment is eliminated. If this screen is not met in order to be considered a business an acquisition would have to include an input and a substantive process that together significantly contribute to the ability to create outputs. This update is effective for public companies for annual and interim reporting periods beginning after December 15, 2017. Early adoption of this guidance is permitted. This guidance requires prospective application following adoption. While the Company is still evaluating this updated guidance, the impact on our financial statements will depend upon the occurrence of any future acquisition activity. In March 2016, the FASB issued an update to the existing guidance under the Compensation-Stock Compensation topic of the Codification. This update simplifies several aspects of accounting for stock compensation including accounting for income taxes, classification of awards as liabilities or equity, forfeitures and classification on the statement of cash flows. This update was effective for public companies for annual and interim reporting periods beginning after December 15, 2016. As such, we adopted this guidance effective January 1, 2017. Upon adoption the Company recognized $8.9 million in previously unrecorded windfall benefits on a modified retrospective basis through a cumulative-effect adjustment to the beginning balance of our accumulated deficit. All windfalls or shortfalls are now recognized as a component of income tax expense in the period they occur. The Company elected to recognize the effect of pre-vesting forfeitures as they actually occur rather than estimating forfeitures each period. In February 2016, the FASB issued an update to the existing guidance under the Leases topic of the Codification. Under the new guidance, lessees will be 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. This update requires a modified retrospective transition as of the beginning of the earliest comparative period presented in the financial statements. This update is effective for public companies for fiscal years beginning after December 15, 2018, including interim periods within those fiscal years, with early adoption permitted. The Company has a significant number of leases, primarily related to real estate and rolling stock, which are accounted for as operating leases under existing guidance. While we are currently evaluating the impact of this new guidance on our financial statements, we are expecting a significant impact to our balance sheet upon adoption. In July 2015, the FASB issued an update to the existing guidance under the Inventory topic of the Codification. This update changes the subsequent measurement of inventory from lower of cost or market to lower of cost and net realizable value. We adopted this guidance effective January 1, 2017 on a prospective basis. The adoption of this guidance did not have an impact on our financial statements. In May 2014, the FASB issued an update to the existing guidance under the Revenue Recognition topic of the Codification which is a comprehensive new revenue recognition model requiring a company to 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. Subsequent to issuance of the original update, the FASB issued several further updates amending this new guidance. In April 2016, the FASB issued an update clarifying issues related to identifying performance obligations and licensing. In May 2016, the FASB issued an update regarding the assessment of collectability criteria, presentation of sales taxes, measurement of noncash consideration and transition guidance for completed contracts and contract modifications. The Company intends to adopt this guidance beginning on January 1, 2018 on a modified retrospective basis. While we are still evaluating the impact of these updates on our financial statements, we anticipate that this guidance will primarily impact our contracts with service elements. Under current guidance, we recognize sales from contracts with service elements on the completed contract method when these contracts are completed within 30 days. The remaining contracts with service elements are recognized under the percentage of completion method. Under this updated guidance, we anticipate that revenue related to our contracts with service elements will generally be recognized over time based on the extent of progress towards completion of the performance obligation because of continuous transfer of control to the customer. We anticipate the impact from adoption to primarily be associated with deferred revenue on contracts outstanding at December 31, 2017 accounted for under the completed contract method, which is anticipated to be generally recognized earlier under this new guidance.

1. Basis of Presentation

Builders FirstSource, Inc., a Delaware corporation formed in 1998, is a leading supplier of building materials, manufactured components and construction services to professional contractors, sub-contractors, and consumers. The Company operates 400 locations in 40 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, 2016 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, 2016 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, 2016 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.

Recent Accounting Pronouncements

In May 2017, the Financial Accounting Standards Board (“FASB”) issued an update to the existing guidance under the Compensation-Stock Compensation topic of the Accounting Standards Codification (“Codification”) to clarify when modification accounting would be applied for a change to the terms or conditions of a share-based award. Under this new guidance modification accounting is required only if the fair value, the vesting conditions, or the classification of the award changes as a result of the change in terms or conditions. This guidance is required to be adopted on a prospective basis for annual periods beginning on or after December 15, 2017 with early adoption permitted. The Company does not regularly modify the terms and conditions of its share-based awards and does not expect the adoption of this guidance to have a significant impact on our financial statements.

In January 2017, the FASB issued an update to the existing guidance under the Intangibles-Goodwill and Other topic of the Codification to simplify the accounting for goodwill impairment. The guidance removes Step 2 of the goodwill impairment test, which requires a hypothetical purchase price allocation. A goodwill impairment will now be the amount by which a reporting unit’s carrying value exceeds its fair value, not to exceed the carrying amount of goodwill. All of the other goodwill impairment guidance will remain largely unchanged, including the option to perform a qualitative assessment to determine if a quantitative impairment test is necessary. This update is effective for annual and any interim goodwill impairment tests in fiscal years beginning after December 15, 2019. Early adoption of this guidance is permitted for annual or interim goodwill tests performed after January 1, 2017. As such, the Company intends to adopt this guidance in the fourth quarter of 2017 in connection with its annual goodwill impairment test. This guidance will be applied on a prospective basis following adoption.

In January 2017, the FASB issued an update to the existing guidance under the Business Combinations topic of the Codification. This update revises the definition of a business. Under this guidance when substantially all of the assets acquired are concentrated in a single asset (or group of similar assets) the assets acquired would not be considered a business. If this initial screen is met the need for further assessment is eliminated. If this screen is not met in order to be considered a business an acquisition would have to include an input and a substantive process that together significantly contribute to the ability to create outputs. This update is effective for public companies for annual and interim reporting periods beginning after December 15, 2017. Early adoption of this guidance is permitted. This guidance requires prospective application following adoption. While the Company is still evaluating this updated guidance, the impact on our financial statements will depend upon the occurrence of any future acquisition activity.

In March 2016, the FASB issued an update to the existing guidance under the Compensation-Stock Compensation topic of the Codification. This update simplifies several aspects of accounting for stock compensation including accounting for income taxes, classification of awards as liabilities or equity, forfeitures and classification on the statement of cash flows. This update was effective for public companies for annual and interim reporting periods beginning after December 15, 2016. As such, we adopted this guidance effective January 1, 2017. Upon adoption the Company recognized $8.9 million in previously unrecorded windfall benefits on a modified retrospective basis through a cumulative-effect adjustment to the beginning balance of our accumulated deficit. All windfalls or shortfalls are now recognized as a component of income tax expense in the period they occur. The Company elected to recognize the effect of pre-vesting forfeitures as they actually occur rather than estimating forfeitures each period.

In February 2016, the FASB issued an update to the existing guidance under the Leases topic of the Codification. Under the new guidance, lessees will be 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. This update requires a modified retrospective transition as of the beginning of the earliest comparative period presented in the financial statements. This update is effective for public companies for fiscal years beginning after December 15, 2018, including interim periods within those fiscal years, with early adoption permitted. The Company has a significant number of leases, primarily related to real estate and rolling stock, which are accounted for as operating leases under existing guidance. While we are currently evaluating the impact of this new guidance on our financial statements, we are expecting a significant impact to our balance sheet upon adoption.

In July 2015, the FASB issued an update to the existing guidance under the Inventory topic of the Codification. This update changes the subsequent measurement of inventory from lower of cost or market to lower of cost and net realizable value. We adopted this guidance effective January 1, 2017 on a prospective basis. The adoption of this guidance did not have an impact on our financial statements.

In May 2014, the FASB issued an update to the existing guidance under the Revenue Recognition topic of the Codification which is a comprehensive new revenue recognition model requiring a company to 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. Subsequent to issuance of the original update, the FASB issued several further updates amending this new guidance. In April 2016, the FASB issued an update clarifying issues related to identifying performance obligations and licensing. In May 2016, the FASB issued an update regarding the assessment of collectability criteria, presentation of sales taxes, measurement of noncash consideration and transition guidance for completed contracts and contract modifications. The Company intends to adopt this guidance beginning on January 1, 2018 on a modified retrospective basis. While we are still evaluating the impact of these updates on our financial statements, we anticipate that this guidance will primarily impact our contracts with service elements. Under current guidance, we recognize sales from contracts with service elements on the completed contract method when these contracts are completed within 30 days. The remaining contracts with service elements are recognized under the percentage of completion method. Under this updated guidance, we anticipate that revenue related to our contracts with service elements will generally be recognized over time based on the extent of progress towards completion of the performance obligation because of continuous transfer of control to the customer. We anticipate the impact from adoption to primarily be associated with deferred revenue on contracts outstanding at December 31, 2017 accounted for under the completed contract method, which is anticipated to be generally recognized earlier under this new guidance.