Summary of Significant Accounting Policies (Policies)	6 Months Ended
Jun. 30, 2018
Accounting Policies [Abstract]
Basis of Presentation	Basis of PresentationThe accompanying unaudited Condensed Consolidated Financial Statements include the accounts of BlueLinx Holdings Inc. and its wholly owned subsidiaries (the “Company”). These financial statements have been prepared in accordance with the instructions to Form 10-Q and do not include all of the information and footnotes required by accounting principles generally accepted (“GAAP”) in the United States (“U.S.”) for complete financial statements. In the opinion of management, all adjustments (consisting of normal recurring accruals) considered necessary for a fair presentation have been included. These statements should be read in conjunction with the Consolidated Financial Statements and notes thereto included in the Company’s Annual Report on Form 10-K (the “Annual Report on Form 10-K”) for the year ended December 30, 2017, as filed with the Securities and Exchange Commission on March 1, 2018.
Recently Adopted Accounting Standards and Standards Effective in Future Years	Recently Adopted Accounting Standards Revenue from Contracts with Customers. In 2014, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) 2014-09, “Revenue from Contracts with Customers (Topic 606) (“ASC 606”)” that superseded existing revenue recognition guidance. Under this ASU and subsequently issued amendments, revenue is recognized at the time a good or service is transferred to a customer for the amount of consideration received. The standard was effective for the first interim period within annual periods beginning after December 15, 2017, with early adoption permitted for annual periods beginning after December 15, 2016. Entities were permitted to adopt the standard using a “full retrospective” approach (retrospectively to each prior reporting period presented) or a “modified retrospective” approach (reporting the cumulative effect as of the date of adoption). On December 31, 2017, the first day of our fiscal 2018 year, we adopted ASC 606 using the modified retrospective method applied to those contracts which were not completed as of that date. Results for reporting periods beginning after the first day of fiscal 2018 are presented under ASC 606, while prior period amounts are not adjusted and continue to be reported in accordance with our historic accounting under the previous accounting standard, ASC 605. There was no adjustment due to the cumulative impact of adopting ASC 606 (See Note 4). Standards Effective in Future Years Leases. In 2016, the FASB issued ASU No. 2016-02, “Leases (Topic 842).” This standard will require leases with durations greater than twelve months to be recognized on the balance sheet and is effective for interim and annual reporting periods beginning after December 15, 2018. We will adopt this standard, and all related amendments thereto, effective January 1, 2019. We have not completed our assessment, but the adoption of this standard may have a significant impact on our Condensed Consolidated Balance Sheets. However, we do not expect the adoption to have a significant impact on the recognition, measurement or presentation of lease expense within the Condensed Consolidated Statements of Operations and Comprehensive Income (Loss) or the Condensed Consolidated Statements of Cash Flows. Information about our undiscounted future lease payments and the timing of those payments is presented in Note 13, “Lease Commitments,” in our Annual Report on Form 10-K. Goodwill. In January 2017, the FASB issued ASU No. 2017-04, “Intangibles—Goodwill and Other (Topic 350).” This standard is intended to simplify the test for goodwill impairments by removing Step 2 of the goodwill impairment test, which requires a hypothetical purchase price allocation. Under the new ASU, 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. The accounting standard will be effective for reporting periods beginning after December 15, 2019. We have not completed our assessment of the standard but we do not expect the adoption to have a material impact on the Company's consolidated financial position, results of operations and cash flows. We will adopt this standard effective January 1, 2019. Comprehensive Income. In February 2018, the FASB issued ASU No. 2018-02, “Income Statement—Reporting Comprehensive Income (Topic 220).” This standard provides an option to reclassify stranded tax effects within accumulated other comprehensive income (loss) (“AOCI”) to retained earnings due to the U.S. federal corporate income tax rate change in the Tax Cuts and Jobs Act of 2017. This standard is effective for interim and annual reporting periods beginning after December 15, 2018, and early adoption is permitted. We have not completed our assessment, but the adoption of the standard may impact tax amounts stranded in AOCI related to our pension plans. We will adopt this standard effective January 1, 2019.
Revenue Recognition	We recognize revenue when (or as) the following criteria are met: i) contract with the customer has been identified; ii) performance obligations in the contract have been identified; iii) transaction price has been determined; iv) the transaction price has been allocated to the performance obligations; and v) the related performance obligations are satisfied. Contracts with our customers are generally in the form of standard terms and conditions of sale. From time to time, we may enter into specific contracts with some of our larger customers, which may affect delivery terms. Performance obligations in our contracts generally consist solely of delivery of goods. For all sales channel types, consisting of warehouse, direct, and reload sales, we typically satisfy our performance obligations upon shipment. Our customer payment terms are typical for our industry, and may vary by the type and location of our customer and the products or services offered. The term between invoicing and when payment is due is not deemed to be significant by us. For certain sales channels and/or products, our standard terms of payment may be as early as ten days. In addition, we provide inventory to certain customers through pre-arranged agreements on a consignment basis. Customer consigned inventory is maintained and stored by certain customers; however, ownership and risk of loss remains with us. When the consigned inventory is sold by the customer, we recognize revenue on a gross basis, and subsequently adjust for trade allowances at month-end. All revenues recognized are net of trade allowances (i.e., rebates), cash discounts and sales returns. Cash discounts and sales returns are estimated using historical experience. Trade allowances are based on the estimated obligations and historical experience. Adjustments to earnings resulting from revisions to estimates on discounts and returns have been insignificant for each of the reported periods. Certain customers may receive cash-based incentives or credits, which are accounted for as variable consideration. We estimate these amounts based on the expected amount to be provided to customers and reduce revenues recognized. We believe that there will not be significant changes to our estimates of variable consideration.Practical Expedients and Exemptions We generally expense sales commissions when incurred because the amortization period would have been one year or less. These costs are recorded within selling, general, and administrative expense. We have made an accounting policy election to treat any common carrier shipping and handling activities as a fulfillment cost, rather than as a separate obligation or separate promised service
Earnings per Share	We calculate basic earnings (loss) per share by dividing net income (loss) by the weighted average number of common shares outstanding. We calculate diluted earnings per share by dividing net income by the weighted average number of common shares outstanding plus the dilutive effect of outstanding share-based awards, including restricted stock units, performance shares, and performance units.

Summary of Significant Accounting Policies (Policies)

6 Months Ended

Jun. 30, 2018

Basis of PresentationThe accompanying unaudited Condensed Consolidated Financial Statements include the accounts of BlueLinx Holdings Inc. and its wholly owned subsidiaries (the “Company”). These financial statements have been prepared in accordance with the instructions to Form 10-Q and do not include all of the information and footnotes required by accounting principles generally accepted (“GAAP”) in the United States (“U.S.”) for complete financial statements. In the opinion of management, all adjustments (consisting of normal recurring accruals) considered necessary for a fair presentation have been included. These statements should be read in conjunction with the Consolidated Financial Statements and notes thereto included in the Company’s Annual Report on Form 10-K (the “Annual Report on Form 10-K”) for the year ended December 30, 2017, as filed with the Securities and Exchange Commission on March 1, 2018.

Recently Adopted Accounting Standards and Standards Effective in Future Years

Recently Adopted Accounting Standards

Revenue from Contracts with Customers. In 2014, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) 2014-09, “Revenue from Contracts with Customers (Topic 606) (“ASC 606”)” that superseded existing revenue recognition guidance. Under this ASU and subsequently issued amendments, revenue is recognized at the time a good or service is transferred to a customer for the amount of consideration received. The standard was effective for the first interim period within annual periods beginning after December 15, 2017, with early adoption permitted for annual periods beginning after December 15, 2016. Entities were permitted to adopt the standard using a “full retrospective” approach (retrospectively to each prior reporting period presented) or a “modified retrospective” approach (reporting the cumulative effect as of the date of adoption).

On December 31, 2017, the first day of our fiscal 2018 year, we adopted ASC 606 using the modified retrospective method applied to those contracts which were not completed as of that date. Results for reporting periods beginning after the first day of fiscal 2018 are presented under ASC 606, while prior period amounts are not adjusted and continue to be reported in accordance with our historic accounting under the previous accounting standard, ASC 605.

There was no adjustment due to the cumulative impact of adopting ASC 606 (See Note 4).

Standards Effective in Future Years

Leases. In 2016, the FASB issued ASU No. 2016-02, “Leases (Topic 842).” This standard will require leases with durations greater than twelve months to be recognized on the balance sheet and is effective for interim and annual reporting periods beginning after December 15, 2018. We will adopt this standard, and all related amendments thereto, effective January 1, 2019.

We have not completed our assessment, but the adoption of this standard may have a significant impact on our Condensed Consolidated Balance Sheets. However, we do not expect the adoption to have a significant impact on the recognition, measurement or presentation of lease expense within the Condensed Consolidated Statements of Operations and Comprehensive Income (Loss) or the Condensed Consolidated Statements of Cash Flows. Information about our undiscounted future lease payments and the timing of those payments is presented in Note 13, “Lease Commitments,” in our Annual Report on Form 10-K.

Goodwill. In January 2017, the FASB issued ASU No. 2017-04, “Intangibles—Goodwill and Other (Topic 350).” This standard is intended to simplify the test for goodwill impairments by removing Step 2 of the goodwill impairment test, which requires a hypothetical purchase price allocation. Under the new ASU, 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. The accounting standard will be effective for reporting periods beginning after December 15, 2019. We have not completed our assessment of the standard but we do not expect the adoption to have a material impact on the Company's consolidated financial position, results of operations and cash flows. We will adopt this standard effective January 1, 2019.

Comprehensive Income. In February 2018, the FASB issued ASU No. 2018-02, “Income Statement—Reporting Comprehensive Income (Topic 220).” This standard provides an option to reclassify stranded tax effects within accumulated other comprehensive income (loss) (“AOCI”) to retained earnings due to the U.S. federal corporate income tax rate change in the Tax Cuts and Jobs Act of 2017. This standard is effective for interim and annual reporting periods beginning after December 15, 2018, and early adoption is permitted. We have not completed our assessment, but the adoption of the standard may impact tax amounts stranded in AOCI related to our pension plans. We will adopt this standard effective January 1, 2019.

Revenue Recognition

We recognize revenue when (or as) the following criteria are met: i) contract with the customer has been identified; ii) performance obligations in the contract have been identified; iii) transaction price has been determined; iv) the

transaction price has been allocated to the performance obligations; and v) the related performance obligations are satisfied.

Contracts with our customers are generally in the form of standard terms and conditions of sale. From time to time, we may enter into specific contracts with some of our larger customers, which may affect delivery terms. Performance obligations in our contracts generally consist solely of delivery of goods. For all sales channel types, consisting of warehouse, direct, and reload sales, we typically satisfy our performance obligations upon shipment. Our customer payment terms are typical for our industry, and may vary by the type and location of our customer and the products or services offered. The term between invoicing and when payment is due is not deemed to be significant by us. For certain sales channels and/or products, our standard terms of payment may be as early as ten days.

In addition, we provide inventory to certain customers through pre-arranged agreements on a consignment basis. Customer consigned inventory is maintained and stored by certain customers; however, ownership and risk of loss remains with us. When the consigned inventory is sold by the customer, we recognize revenue on a gross basis, and subsequently adjust for trade allowances at month-end.

All revenues recognized are net of trade allowances (i.e., rebates), cash discounts and sales returns. Cash discounts and sales returns are estimated using historical experience. Trade allowances are based on the estimated obligations and historical experience. Adjustments to earnings resulting from revisions to estimates on discounts and returns have been insignificant for each of the reported periods. Certain customers may receive cash-based incentives or credits, which are accounted for as variable consideration. We estimate these amounts based on the expected amount to be provided to customers and reduce revenues recognized. We believe that there will not be significant changes to our estimates of variable consideration.Practical Expedients and Exemptions

We generally expense sales commissions when incurred because the amortization period would have been one year or less. These costs are recorded within selling, general, and administrative expense.

We have made an accounting policy election to treat any common carrier shipping and handling activities as a fulfillment cost, rather than as a separate obligation or separate promised service

Earnings per Share

We calculate basic earnings (loss) per share by dividing net income (loss) by the weighted average number of common shares outstanding. We calculate diluted earnings per share by dividing net income by the weighted average number of common shares outstanding plus the dilutive effect of outstanding share-based awards, including restricted stock units, performance shares, and performance units.