SUMMARY OF ORGANIZATION AND SIGNIFICANT ACCOUNTING POLICIES	9 Months Ended
Sep. 28, 2019
Summary Of Significant Accounting Policies And Recent Accounting Pronouncements [Line Items]
Summary of Organization and Significant Accounting Policies	SUMMARY OF ORGANIZATION AND SIGNIFICANT ACCOUNTING POLICIES Summit Materials, Inc. (“Summit Inc.” and, together with its subsidiaries, “Summit,” “we,” “us,” “our” or the “Company”) is a vertically-integrated construction materials company. The Company is engaged in the production and sale of aggregates, cement, ready-mix concrete, asphalt paving mix and concrete products and owns and operates quarries, sand and gravel pits, two cement plants, cement distribution terminals, ready-mix concrete plants, asphalt plants and landfill sites. It is also engaged in paving and related services. The Company’s three operating and reporting segments are the West, East and Cement segments. Substantially all of the Company’s construction materials, products and services are produced, consumed and performed outdoors, primarily in the spring, summer and fall. Seasonal changes and other weather-related conditions can affect the production and sales volumes of its products and delivery of services. Therefore, the financial results for any interim period are typically not indicative of the results expected for the full year. Furthermore, the Company’s sales and earnings are sensitive to national, regional and local economic conditions, weather conditions and to cyclical changes in construction spending, among other factors. Summit Inc. is a holding corporation operating and controlling all of the business and affairs of Summit Materials Holdings L.P. (“Summit Holdings”) and its subsidiaries and, through Summit Holdings, conducts its business. Summit Inc. owns the majority of the partnership interests of Summit Holdings (see Note 9, Stockholders’ Equity). Summit Materials, LLC (“Summit LLC”) an indirect wholly owned subsidiary of Summit Holdings, conducts the majority of our operations. Summit Materials Finance Corp. (“Summit Finance”), an indirect wholly owned subsidiary of Summit LLC, has jointly issued our Senior Notes as described below. Basis of Presentation—These unaudited consolidated financial statements were prepared in accordance with U.S. generally accepted accounting principles (“U.S. GAAP”) for interim financial information, without audit, pursuant to the rules and regulations of the Securities and Exchange Commission (“SEC”). Certain information and footnote disclosures typically included in financial statements prepared in accordance with U.S. GAAP have been condensed or omitted pursuant to such rules and regulations. These unaudited consolidated financial statements should be read in conjunction with the Company's audited consolidated financial statements and the notes thereto as of and for the year ended December 29, 2018. The Company continues to follow the accounting policies set forth in those audited consolidated financial statements. Management believes that these consolidated interim financial statements include all adjustments, normal and recurring in nature, that are necessary to present fairly the financial position of the Company as of September 28, 2019, the results of operations for the three and nine months ended September 28, 2019 and September 29, 2018 and cash flows for the nine months ended September 28, 2019 and September 29, 2018. Principles of Consolidation—The consolidated financial statements include the accounts of Summit Inc. and its majority owned subsidiaries. All intercompany balances and transactions have been eliminated. As a result of the reorganization into a holding company structure (the “Reorganization”), Summit Holdings became a variable interest entity over which Summit Inc. has 100% voting power and control and for which Summit Inc. has the obligation to absorb losses and the right to receive benefits. For a summary of the changes in Summit Inc.’s ownership of Summit Holdings, see Note 9, Stockholders’ Equity. Use of Estimates—Preparation of these consolidated financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions. These estimates and the underlying assumptions affect the amounts of assets and liabilities reported, disclosures about contingent assets and liabilities and reported amounts of revenue and expenses. Such estimates include the valuation of accounts receivable, inventories, valuation of deferred tax assets, goodwill, intangibles and other long-lived assets, the tax receivable agreement ("TRA") liability, pension and other postretirement obligations and asset retirement obligations. Estimates also include revenue earned on contracts and costs to complete contracts. Most of the Company’s paving and related services are performed under fixed unit-price contracts with state and local governmental entities. Management regularly evaluates its estimates and assumptions based on historical experience and other factors, including the current economic environment. As future events and their effects cannot be determined with precision, actual results can differ significantly from estimates made. Changes in estimates, including those resulting from continuing changes in the economic environment, are reflected in the Company’s consolidated financial statements when the change in estimate occurs. Business and Credit Concentrations—The Company’s operations are conducted primarily across 23 U.S. states and in British Columbia, Canada, with the most significant revenue generated in Texas, Utah, Kansas and Missouri. The Company’s accounts receivable consist primarily of amounts due from customers within these areas. Therefore, collection of these accounts is dependent on the economic conditions in the aforementioned states, as well as specific situations affecting individual customers. Credit granted within the Company’s trade areas has been granted to many customers, and management does not believe that a significant concentration of credit exists with respect to any individual customer or group of customers. No single customer accounted for more than 10% of the Company’s total revenue in the three and nine months ended September 28, 2019 or September 29, 2018. Revenue Recognition—We earn revenue from the sale of products, which primarily include aggregates, cement, ready-mix concrete and asphalt, but also include concrete products and plastics components, and from the provision of services, which are primarily paving and related services, but also include landfill operations, the receipt and disposal of waste that is converted to fuel for use in our cement plants and underground storage space rental. Products We earn revenue from the sale of products, which primarily include aggregates, cement, ready-mix concrete and asphalt, but also include concrete products, net of discounts or allowances, if any, and freight and delivery charges billed to customers. Freight and delivery charges associated with cement sales are recorded on a net basis together with freight costs within cost of sales. Revenue for product sales is recognized when evidence of an arrangement exists and when control passes, which generally is when the product is shipped. Services We earn revenue from the provision of services, which are primarily paving and related services, but also include landfill operations, and the receipt and disposal of waste that is converted to fuel for use in our cement plants. Revenue from the receipt of waste fuels is recognized when the waste is accepted and a corresponding liability is recognized for the costs to process the waste into fuel for the manufacturing of cement or to ship the waste offsite for disposal in accordance with applicable regulations. Revenue derived from paving and related services is recognized using the percentage of completion method, which approximates progress towards completion. Under the percentage of completion method, we recognize paving and related services revenue as services are rendered. The majority of our construction service contracts are completed within one year, but may occasionally extend beyond this time frame. We estimate profit as the difference between total estimated revenue and total estimated cost of a contract and recognize that profit over the life of the contract based on input measures. We generally measure progress toward completion on long-term paving and related services contracts based on the proportion of costs incurred to date relative to total estimated costs at completion. We include revisions of estimated profits on contracts in earnings under the cumulative catch-up method, under which the effect of revisions in estimates is recognized immediately. If a revised estimate of contract profitability reveals an anticipated loss on the contract, we recognize the loss in the period it is identified. The percentage of completion method of accounting involves the use of various estimating techniques to project costs at completion, and in some cases includes estimates of recoveries asserted against the customer for changes in specifications or other disputes. Contract estimates involve various assumptions and projections relative to the outcome of future events over multiple periods, including future labor productivity and availability, the nature and complexity of the work to be performed, the cost and availability of materials, the effect of delayed performance, and the availability and timing of funding from the customer. These estimates are based on our best judgment. A significant change in one or more of these estimates could affect the profitability of one or more of our contracts. We review our contract estimates regularly to assess revisions in contract values and estimated costs at completion. Inherent uncertainties in estimating costs make it at least reasonably possible that the estimates used will change within the near term and over the life of the contracts. No material adjustments to a contract were recognized in the three and nine months ended September 28, 2019. Costs and estimated earnings in excess of billings are composed principally of revenue recognized on contracts on the percentage of completion method for which billings had not been presented to customers because the amounts were not billable under the contract terms at the balance sheet date. In accordance with the contract terms, the unbilled receivables at the balance sheet date are expected to be billed in following periods. Billings in excess of costs and estimated earnings represent billings in excess of revenue recognized. Contract assets and liabilities are netted on a contract-by-contract basis. Earnings per Share—The Company computes basic earnings per share attributable to stockholders by dividing income attributable to Summit Inc. by the weighted-average shares of Class A common stock outstanding. Diluted earnings per share reflects the potential dilution beyond shares for basic earnings per share that could occur if securities or other contracts to issue common stock were exercised, converted into common stock, or resulted in the issuance of common stock that would have shared in the Company’s earnings. Since the Class B common stock has no economic value, those shares are not included in the weighted-average common share amount for basic or diluted earnings per share. In addition, as the shares of Class A common stock are issued by Summit Inc., the earnings and equity interests of noncontrolling interests are not included in basic earnings per share. Tax Receivable Agreement— When Class A limited partnership units of Summit Holdings (“LP Units”) are exchanged for shares of Class A common stock of Summit Inc. or Summit Inc. purchases LP Units for cash, this results in increases in Summit Inc.’s share of the tax basis of the tangible and intangible assets, which increases the tax depreciation and amortization deductions that otherwise would not have been available to Summit Inc. These increases in tax basis and tax depreciation and amortization deductions are expected to reduce the amount of cash taxes that we would otherwise be required to pay in the future. Prior to our initial public offering (“IPO”), we entered into a TRA with the pre-IPO owners that requires us to pay the pre-IPO owners or their permitted assignees 85% of the amount of cash savings, if any, in U.S. federal, state, and local income tax that we actually realize as a result of these exchanges. These benefits include (1) increases in the tax basis of tangible and intangible assets of Summit Holdings and certain other tax benefits related to entering into the TRA, (2) tax benefits attributable to payments under the TRA, or (3) under certain circumstances such as an early termination of the TRA, we are deemed to realize, as a result of the increases in tax basis in connection with exchanges by the pre-IPO owners described above and certain other tax benefits attributable to payments under the TRA. We periodically evaluate the realizability of the deferred tax assets resulting from the exchange of LP Units for Class A common stock. If the deferred tax assets are determined to be realizable, we then assess whether payment of amounts under the TRA have become probable. If so, we record a TRA liability equal to 85% of such deferred tax assets, and the remaining 15% as an increase to additional paid-in capital. If a deferred tax asset subject to the TRA is determined not to be realizable and therefore subject to a valuation allowance, we do not record a TRA liability for such deferred tax assets. In subsequent periods, we assess the realizability of all of our deferred tax assets subject to the TRA. Should we determine a deferred tax asset with a valuation allowance is realizable in a subsequent period, the related valuation allowance will be released and consideration of a corresponding TRA liability will be assessed. The realizability of deferred tax assets, including those subject to the TRA, is dependent upon the generation of future taxable income during the periods in which those deferred tax assets become deductible and consideration of prudent and feasible tax-planning strategies. The measurement of the TRA liability is accounted for as a contingent liability. Therefore, once we determine that a payment to a pre-IPO owner has become probable and can be estimated, the estimate of payment will be accrued. New Accounting Standards — In February 2016, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) No. 2016-02, Leases (Topic 842), which requires lessees to recognize most leases on the balance sheet. Lessees are required to disclose more quantitative and qualitative information about the leases than current U.S. GAAP requires. The ASU and subsequent amendments issued in 2018 are effective for public entities for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2018. We adopted the standard effective December 30, 2018 using the modified retrospective approach. The modified retrospective approach provides a method for recording existing leases at adoption. In addition, we elected the package of practical expedients permitted under the transition guidance within the new standard, which among other things, allowed us to carry forward the historical lease classification. In addition, we elected the hindsight practical expedient to determine the lease term for existing leases. The most significant impact upon adoption was the recognition of $36.8 million of operating lease right-of-use assets and $36.8 million operating lease liabilities. The standard had no material impact on our statement of cash flows. In August 2017, the FASB issued ASU No. 2017-12, Derivatives and Hedging (Topic 815): Targeted Improvements to Accounting for Hedging Activities, allowing more financial and nonfinancial hedging strategies to be eligible for hedge accounting. The ASU is effective for fiscal years beginning after December 15, 2018 and interim periods within those fiscal years. The adoption of this new ASU did not have a material impact on our consolidated financial results. In June 2018, the FASB issued ASU No. 2018-07, Compensation—Stock Compensation (Topic 718): Improvements to Nonemployee Share-Based Payment Accounting, increasing the scope of Topic 718 to include share-based payment transactions for acquiring goods and services from nonemployees. The ASU is effective for fiscal years beginning after December 15, 2018 and interim periods within those fiscal years. The adoption of this new ASU did not have a material impact on our consolidated financial results.
Summit Materials, LLC
Summary Of Significant Accounting Policies And Recent Accounting Pronouncements [Line Items]
Summary of Organization and Significant Accounting Policies	SUMMARY OF ORGANIZATION AND SIGNIFICANT ACCOUNTING POLICIES Summit Materials, LLC (“Summit LLC” and, together with its subsidiaries, “Summit,” “we,” “us,” “our” or the “Company”) is a vertically-integrated construction materials company. The Company is engaged in the production and sale of aggregates, cement, ready-mix concrete, asphalt paving mix and concrete products and owns and operates quarries, sand and gravel pits, two cement plants, cement distribution terminals, ready-mix concrete plants, asphalt plants and landfill sites. It is also engaged in paving and related services. The Company’s three operating and reporting segments are the West, East and Cement segments. Substantially all of the Company’s construction materials, products and services are produced, consumed and performed outdoors, primarily in the spring, summer and fall. Seasonal changes and other weather-related conditions can affect the production and sales volumes of its products and delivery of services. Therefore, the financial results for any interim period are typically not indicative of the results expected for the full year. Furthermore, the Company’s sales and earnings are sensitive to national, regional and local economic conditions, weather conditions and to cyclical changes in construction spending, among other factors. Summit LLC is a wholly owned indirect subsidiary of Summit Materials Holdings L.P. (“Summit Holdings”), whose primary owner is Summit Materials, Inc. (“Summit Inc.”). Summit Inc. was formed as a Delaware corporation on September 23, 2014. Its sole material asset is a controlling equity interest in Summit Holdings. Pursuant to a reorganization into a holding company structure (the “Reorganization”) consummated in connection with Summit Inc.’s March 2015 initial public offering, Summit Inc. became a holding corporation operating and controlling all of the business and affairs of Summit Holdings and its subsidiaries, including Summit LLC. Basis of Presentation—These unaudited consolidated financial statements were prepared in accordance with U.S. generally accepted accounting principles (“U.S. GAAP”) for interim financial information, without audit, pursuant to the rules and regulations of the Securities and Exchange Commission (“SEC”). Certain information and footnote disclosures typically included in financial statements prepared in accordance with U.S. GAAP have been condensed or omitted pursuant to such rules and regulations. These unaudited consolidated financial statements should be read in conjunction with the Company’s audited consolidated financial statements and the notes thereto as of and for the year ended December 29, 2018. The Company continues to follow the accounting policies set forth in those audited consolidated financial statements. Management believes that these consolidated interim financial statements include all adjustments, normal and recurring in nature, that are necessary to present fairly the financial position of the Company as of September 28, 2019, the results of operations for the three and nine months ended September 28, 2019 and September 29, 2018 and cash flows for the nine months ended September 28, 2019 and September 29, 2018. Use of Estimates—Preparation of these consolidated financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions. These estimates and the underlying assumptions affect the amounts of assets and liabilities reported, disclosures about contingent assets and liabilities and reported amounts of revenue and expenses. Such estimates include the valuation of accounts receivable, inventories, valuation of deferred tax assets, goodwill, intangibles and other long-lived assets, pension and other postretirement obligations and asset retirement obligations. Estimates also include revenue earned on contracts and costs to complete contracts. Most of the Company’s paving and related services are performed under fixed unit-price contracts with state and local governmental entities. Management regularly evaluates its estimates and assumptions based on historical experience and other factors, including the current economic environment. As future events and their effects cannot be determined with precision, actual results can differ significantly from estimates made. Changes in estimates, including those resulting from continuing changes in the economic environment, are reflected in the Company’s consolidated financial statements when the change in estimate occurs. Business and Credit Concentrations—The Company’s operations are conducted primarily across 23 U.S. states and in British Columbia, Canada, with the most significant revenue generated in Texas, Utah, Kansas and Missouri. The Company’s accounts receivable consist primarily of amounts due from customers within these areas. Therefore, collection of these accounts is dependent on the economic conditions in the aforementioned states, as well as specific situations affecting individual customers. Credit granted within the Company’s trade areas has been granted to many customers, and management does not believe that a significant concentration of credit exists with respect to any individual customer or group of customers. No single customer accounted for more than 10% of the Company’s total revenue in the three and nine months ended September 28, 2019 or September 29, 2018. Revenue Recognition—We earn revenue from the sale of products, which primarily include aggregates, cement, ready-mix concrete and asphalt, but also include concrete products and plastics components, and from the provision of services, which are primarily paving and related services, but also include landfill operations, the receipt and disposal of waste that is converted to fuel for use in our cement plants and underground storage space rental. Products We earn revenue from the sale of products, which primarily include aggregates, cement, ready-mix concrete and asphalt, but also include concrete products, net of discounts or allowances, if any, and freight and delivery charges billed to customers. Freight and delivery charges associated with cement sales are recorded on a net basis together with freight costs within cost of sales. Revenue for product sales is recognized when evidence of an arrangement exists and when control passes, which generally is when the product is shipped. Services We earn revenue from the provision of services, which are primarily paving and related services, but also include landfill operations, and the receipt and disposal of waste that is converted to fuel for use in our cement plants. Revenue from the receipt of waste fuels is recognized when the waste is accepted and a corresponding liability is recognized for the costs to process the waste into fuel for the manufacturing of cement or to ship the waste offsite for disposal in accordance with applicable regulations. Revenue derived from paving and related services is recognized using the percentage of completion method, which approximates progress towards completion. Under the percentage of completion method, we recognize paving and related services revenue as services are rendered. The majority of our construction service contracts are completed within one year, but may occasionally extend beyond this time frame. We estimate profit as the difference between total estimated revenue and total estimated cost of a contract and recognize that profit over the life of the contract based on input measures. We generally measure progress toward completion on long-term paving and related services contracts based on the proportion of costs incurred to date relative to total estimated costs at completion. We include revisions of estimated profits on contracts in earnings under the cumulative catch-up method, under which the effect of revisions in estimates is recognized immediately. If a revised estimate of contract profitability reveals an anticipated loss on the contract, we recognize the loss in the period it is identified. The percentage of completion method of accounting involves the use of various estimating techniques to project costs at completion, and in some cases includes estimates of recoveries asserted against the customer for changes in specifications or other disputes. Contract estimates involve various assumptions and projections relative to the outcome of future events over multiple periods, including future labor productivity and availability, the nature and complexity of the work to be performed, the cost and availability of materials, the effect of delayed performance, and the availability and timing of funding from the customer. These estimates are based on our best judgment. A significant change in one or more of these estimates could affect the profitability of one or more of our contracts. We review our contract estimates regularly to assess revisions in contract values and estimated costs at completion. Inherent uncertainties in estimating costs make it at least reasonably possible that the estimates used will change within the near term and over the life of the contracts. No material adjustments to a contract were recognized in the three and nine months ended September 28, 2019. Costs and estimated earnings in excess of billings are composed principally of revenue recognized on contracts on the percentage of completion method for which billings had not been presented to customers because the amounts were not billable under the contract terms at the balance sheet date. In accordance with the contract terms, the unbilled receivables at the balance sheet date are expected to be billed in following periods. Billings in excess of costs and estimated earnings represent billings in excess of revenue recognized. Contract assets and liabilities are netted on a contract-by-contract basis. New Accounting Standards — In February 2016, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) No. 2016-02, Leases (Topic 842), which requires lessees to recognize most leases on the balance sheet. Lessees are required to disclose more quantitative and qualitative information about the leases than current U.S. GAAP requires. The ASU and subsequent amendments issued in 2018 are effective for public entities for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2018. We adopted the standard effective December 30, 2018 using the modified retrospective approach. The modified retrospective approach provides a method for recording existing leases at adoption. In addition, we elected the package of practical expedients permitted under the transition guidance within the new standard, which among other things, allowed us to carry forward the historical lease classification. In addition, we elected the hindsight practical expedient to determine the lease term for existing leases. The most significant impact upon adoption was the recognition of $36.8 million of operating lease right-of-use assets and $36.8 million operating lease liabilities. The standard had no material impact on our statement of cash flows. In August 2017, the FASB issued ASU No. 2017-12, Derivatives and Hedging (Topic 815): Targeted Improvements to Accounting for Hedging Activities, allowing more financial and nonfinancial hedging strategies to be eligible for hedge accounting. The ASU is effective for fiscal years beginning after December 15, 2018 and interim periods within those fiscal years. The adoption of this new ASU did not have a material impact on our consolidated financial results. In June 2018, the FASB issued ASU No. 2018-07, Compensation-Stock Compensation (Topic 718): Improvements to Nonemployee Share-Based Payment Accounting, increasing the scope of Topic 718 to include share-based payment transactions for acquiring goods and services from nonemployees. The ASU is effective for fiscal years beginning after December 15, 2018 and interim periods within those fiscal years. The adoption of this new ASU did not have a material impact on our consolidated financial results.

SUMMARY OF ORGANIZATION AND SIGNIFICANT ACCOUNTING POLICIES

SUMMARY OF ORGANIZATION AND SIGNIFICANT ACCOUNTING POLICIES

Summit Materials, Inc. (“Summit Inc.” and, together with its subsidiaries, “Summit,” “we,” “us,” “our” or the “Company”) is a vertically-integrated construction materials company. The Company is engaged in the production and sale of aggregates, cement, ready-mix concrete, asphalt paving mix and concrete products and owns and operates quarries, sand and gravel pits, two cement plants, cement distribution terminals, ready-mix concrete plants, asphalt plants and landfill sites. It is also engaged in paving and related services. The Company’s three operating and reporting segments are the West, East and Cement segments.

Substantially all of the Company’s construction materials, products and services are produced, consumed and performed outdoors, primarily in the spring, summer and fall. Seasonal changes and other weather-related conditions can affect the production and sales volumes of its products and delivery of services. Therefore, the financial results for any interim period are typically not indicative of the results expected for the full year. Furthermore, the Company’s sales and earnings are sensitive to national, regional and local economic conditions, weather conditions and to cyclical changes in construction spending, among other factors.

Summit Inc. is a holding corporation operating and controlling all of the business and affairs of Summit Materials Holdings L.P. (“Summit Holdings”) and its subsidiaries and, through Summit Holdings, conducts its business. Summit Inc. owns the majority of the partnership interests of Summit Holdings (see Note 9, Stockholders’ Equity). Summit Materials, LLC (“Summit LLC”) an indirect wholly owned subsidiary of Summit Holdings, conducts the majority of our operations. Summit Materials Finance Corp. (“Summit Finance”), an indirect wholly owned subsidiary of Summit LLC, has jointly issued our Senior Notes as described below.

Basis of Presentation—These unaudited consolidated financial statements were prepared in accordance with U.S. generally accepted accounting principles (“U.S. GAAP”) for interim financial information, without audit, pursuant to the rules and regulations of the Securities and Exchange Commission (“SEC”). Certain information and footnote disclosures typically included in financial statements prepared in accordance with U.S. GAAP have been condensed or omitted pursuant to such rules and regulations. These unaudited consolidated financial statements should be read in conjunction with the Company's audited consolidated financial statements and the notes thereto as of and for the year ended December 29, 2018. The Company continues to follow the accounting policies set forth in those audited consolidated financial statements.

Management believes that these consolidated interim financial statements include all adjustments, normal and recurring in nature, that are necessary to present fairly the financial position of the Company as of September 28, 2019, the results of operations for the three and nine months ended September 28, 2019 and September 29, 2018 and cash flows for the nine months ended September 28, 2019 and September 29, 2018.

Principles of Consolidation—The consolidated financial statements include the accounts of Summit Inc. and its majority owned subsidiaries. All intercompany balances and transactions have been eliminated. As a result of the reorganization into a holding company structure (the “Reorganization”), Summit Holdings became a variable interest entity over which Summit Inc. has 100% voting power and control and for which Summit Inc. has the obligation to absorb losses and the right to receive benefits.

For a summary of the changes in Summit Inc.’s ownership of Summit Holdings, see Note 9, Stockholders’ Equity.

Use of Estimates—Preparation of these consolidated financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions. These estimates and the underlying assumptions affect the amounts of assets and liabilities reported, disclosures about contingent assets and liabilities and reported amounts of revenue and expenses. Such estimates include the valuation of accounts receivable, inventories, valuation of deferred tax assets, goodwill, intangibles and other long-lived assets, the tax receivable agreement ("TRA") liability, pension and other postretirement obligations and asset retirement obligations. Estimates also include revenue earned on contracts and costs to complete contracts. Most of the Company’s paving and related services are performed under fixed unit-price contracts with state and local governmental entities. Management regularly evaluates its estimates and assumptions based on historical

experience and other factors, including the current economic environment. As future events and their effects cannot be determined with precision, actual results can differ significantly from estimates made. Changes in estimates, including those resulting from continuing changes in the economic environment, are reflected in the Company’s consolidated financial statements when the change in estimate occurs.

Business and Credit Concentrations—The Company’s operations are conducted primarily across 23 U.S. states and in British Columbia, Canada, with the most significant revenue generated in Texas, Utah, Kansas and Missouri. The Company’s accounts receivable consist primarily of amounts due from customers within these areas. Therefore, collection of these accounts is dependent on the economic conditions in the aforementioned states, as well as specific situations affecting individual customers. Credit granted within the Company’s trade areas has been granted to many customers, and management does not believe that a significant concentration of credit exists with respect to any individual customer or group of customers. No single customer accounted for more than 10% of the Company’s total revenue in the three and nine months ended September 28, 2019 or September 29, 2018.

Revenue Recognition—We earn revenue from the sale of products, which primarily include aggregates, cement, ready-mix concrete and asphalt, but also include concrete products and plastics components, and from the provision of services, which are primarily paving and related services, but also include landfill operations, the receipt and disposal of waste that is converted to fuel for use in our cement plants and underground storage space rental.

We earn revenue from the sale of products, which primarily include aggregates, cement, ready-mix concrete and asphalt, but also include concrete products, net of discounts or allowances, if any, and freight and delivery charges billed to customers. Freight and delivery charges associated with cement sales are recorded on a net basis together with freight costs within cost of sales. Revenue for product sales is recognized when evidence of an arrangement exists and when control passes, which generally is when the product is shipped.

We earn revenue from the provision of services, which are primarily paving and related services, but also include landfill operations, and the receipt and disposal of waste that is converted to fuel for use in our cement plants. Revenue from the receipt of waste fuels is recognized when the waste is accepted and a corresponding liability is recognized for the costs to process the waste into fuel for the manufacturing of cement or to ship the waste offsite for disposal in accordance with applicable regulations.

Revenue derived from paving and related services is recognized using the percentage of completion method, which approximates progress towards completion. Under the percentage of completion method, we recognize paving and related services revenue as services are rendered. The majority of our construction service contracts are completed within one year, but may occasionally extend beyond this time frame. We estimate profit as the difference between total estimated revenue and total estimated cost of a contract and recognize that profit over the life of the contract based on input measures. We generally measure progress toward completion on long-term paving and related services contracts based on the proportion of costs incurred to date relative to total estimated costs at completion. We include revisions of estimated profits on contracts in earnings under the cumulative catch-up method, under which the effect of revisions in estimates is recognized immediately. If a revised estimate of contract profitability reveals an anticipated loss on the contract, we recognize the loss in the period it is identified.

The percentage of completion method of accounting involves the use of various estimating techniques to project costs at completion, and in some cases includes estimates of recoveries asserted against the customer for changes in specifications or other disputes. Contract estimates involve various assumptions and projections relative to the outcome of future events over multiple periods, including future labor productivity and availability, the nature and complexity of the work to be performed, the cost and availability of materials, the effect of delayed performance, and the availability and timing of funding from the customer. These estimates are based on our best judgment. A significant change in one or more of these estimates could affect the profitability of one or more of our contracts. We review our contract estimates regularly to assess revisions in contract values and estimated costs at completion. Inherent uncertainties in estimating costs make it at least reasonably possible that the estimates used will change within the near term and over the life of the contracts. No material adjustments to a contract were recognized in the three and nine months ended September 28, 2019.

billable under the contract terms at the balance sheet date. In accordance with the contract terms, the unbilled receivables at the balance sheet date are expected to be billed in following periods. Billings in excess of costs and estimated earnings represent billings in excess of revenue recognized. Contract assets and liabilities are netted on a contract-by-contract basis.

Earnings per Share—The Company computes basic earnings per share attributable to stockholders by dividing income attributable to Summit Inc. by the weighted-average shares of Class A common stock outstanding. Diluted earnings per share reflects the potential dilution beyond shares for basic earnings per share that could occur if securities or other contracts to issue common stock were exercised, converted into common stock, or resulted in the issuance of common stock that would have shared in the Company’s earnings. Since the Class B common stock has no economic value, those shares are not included in the weighted-average common share amount for basic or diluted earnings per share. In addition, as the shares of Class A common stock are issued by Summit Inc., the earnings and equity interests of noncontrolling interests are not included in basic earnings per share.

Tax Receivable Agreement— When Class A limited partnership units of Summit Holdings (“LP Units”) are exchanged for shares of Class A common stock of Summit Inc. or Summit Inc. purchases LP Units for cash, this results in increases in Summit Inc.’s share of the tax basis of the tangible and intangible assets, which increases the tax depreciation and amortization deductions that otherwise would not have been available to Summit Inc. These increases in tax basis and tax depreciation and amortization deductions are expected to reduce the amount of cash taxes that we would otherwise be required to pay in the future. Prior to our initial public offering (“IPO”), we entered into a TRA with the pre-IPO owners that requires us to pay the pre-IPO owners or their permitted assignees 85% of the amount of cash savings, if any, in U.S. federal, state, and local income tax that we actually realize as a result of these exchanges. These benefits include (1) increases in the tax basis of tangible and intangible assets of Summit Holdings and certain other tax benefits related to entering into the TRA, (2) tax benefits attributable to payments under the TRA, or (3) under certain circumstances such as an early termination of the TRA, we are deemed to realize, as a result of the increases in tax basis in connection with exchanges by the pre-IPO owners described above and certain other tax benefits attributable to payments under the TRA.

We periodically evaluate the realizability of the deferred tax assets resulting from the exchange of LP Units for Class A common stock. If the deferred tax assets are determined to be realizable, we then assess whether payment of amounts under the TRA have become probable. If so, we record a TRA liability equal to 85% of such deferred tax assets, and the remaining 15% as an increase to additional paid-in capital. If a deferred tax asset subject to the TRA is determined not to be realizable and therefore subject to a valuation allowance, we do not record a TRA liability for such deferred tax assets. In subsequent periods, we assess the realizability of all of our deferred tax assets subject to the TRA. Should we determine a deferred tax asset with a valuation allowance is realizable in a subsequent period, the related valuation allowance will be released and consideration of a corresponding TRA liability will be assessed. The realizability of deferred tax assets, including those subject to the TRA, is dependent upon the generation of future taxable income during the periods in which those deferred tax assets become deductible and consideration of prudent and feasible tax-planning strategies.

The measurement of the TRA liability is accounted for as a contingent liability. Therefore, once we determine that a payment to a pre-IPO owner has become probable and can be estimated, the estimate of payment will be accrued.

New Accounting Standards — In February 2016, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) No. 2016-02, Leases (Topic 842), which requires lessees to recognize most leases on the balance sheet. Lessees are required to disclose more quantitative and qualitative information about the leases than current U.S. GAAP requires. The ASU and subsequent amendments issued in 2018 are effective for public entities for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2018. We adopted the standard effective December 30, 2018 using the modified retrospective approach.

The modified retrospective approach provides a method for recording existing leases at adoption. In addition, we elected the package of practical expedients permitted under the transition guidance within the new standard, which among other things, allowed us to carry forward the historical lease classification. In addition, we elected the hindsight practical expedient to determine the lease term for existing leases.

The most significant impact upon adoption was the recognition of $36.8 million of operating lease right-of-use assets and $36.8 million operating lease liabilities. The standard had no material impact on our statement of cash flows.

In August 2017, the FASB issued ASU No. 2017-12, Derivatives and Hedging (Topic 815): Targeted Improvements to Accounting for Hedging Activities, allowing more financial and nonfinancial hedging strategies to be eligible for hedge accounting. The ASU is effective for fiscal years beginning after December 15, 2018 and interim periods within those fiscal years. The adoption of this new ASU did not have a material impact on our consolidated financial results.

In June 2018, the FASB issued ASU No. 2018-07, Compensation—Stock Compensation (Topic 718): Improvements to Nonemployee Share-Based Payment Accounting, increasing the scope of Topic 718 to include share-based payment transactions for acquiring goods and services from nonemployees. The ASU is effective for fiscal years beginning after December 15, 2018 and interim periods within those fiscal years. The adoption of this new ASU did not have a material impact on our consolidated financial results.

Summit Materials, LLC (“Summit LLC” and, together with its subsidiaries, “Summit,” “we,” “us,” “our” or the “Company”) is a vertically-integrated construction materials company. The Company is engaged in the production and sale of aggregates, cement, ready-mix concrete, asphalt paving mix and concrete products and owns and operates quarries, sand and gravel pits, two cement plants, cement distribution terminals, ready-mix concrete plants, asphalt plants and landfill sites. It is also engaged in paving and related services. The Company’s three operating and reporting segments are the West, East and Cement segments.

Summit LLC is a wholly owned indirect subsidiary of Summit Materials Holdings L.P. (“Summit Holdings”), whose primary owner is Summit Materials, Inc. (“Summit Inc.”). Summit Inc. was formed as a Delaware corporation on September 23, 2014. Its sole material asset is a controlling equity interest in Summit Holdings. Pursuant to a reorganization into a holding company structure (the “Reorganization”) consummated in connection with Summit Inc.’s March 2015 initial public offering, Summit Inc. became a holding corporation operating and controlling all of the business and affairs of Summit Holdings and its subsidiaries, including Summit LLC.

Basis of Presentation—These unaudited consolidated financial statements were prepared in accordance with U.S. generally accepted accounting principles (“U.S. GAAP”) for interim financial information, without audit, pursuant to the rules and regulations of the Securities and Exchange Commission (“SEC”). Certain information and footnote disclosures typically included in financial statements prepared in accordance with U.S. GAAP have been condensed or omitted pursuant to such rules and regulations. These unaudited consolidated financial statements should be read in conjunction with the Company’s audited consolidated financial statements and the notes thereto as of and for the year ended December 29, 2018. The Company continues to follow the accounting policies set forth in those audited consolidated financial statements.

Use of Estimates—Preparation of these consolidated financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions. These estimates and the underlying assumptions affect the amounts of assets and liabilities reported, disclosures about contingent assets and liabilities and reported amounts of revenue and expenses. Such estimates include the valuation of accounts receivable, inventories, valuation of deferred tax assets, goodwill, intangibles and other long-lived assets, pension and other postretirement obligations and asset retirement obligations. Estimates also include revenue earned on contracts and costs to complete contracts. Most of the Company’s paving and related services are performed under fixed unit-price contracts with state and local governmental entities. Management regularly evaluates its estimates and assumptions based on historical experience and other factors, including the current economic environment. As future events and their effects cannot be determined with precision, actual results can differ significantly from estimates made. Changes in estimates, including those resulting from continuing changes in the economic environment, are reflected in the Company’s consolidated financial statements when the change in estimate occurs.

believe that a significant concentration of credit exists with respect to any individual customer or group of customers. No single customer accounted for more than 10% of the Company’s total revenue in the three and nine months ended September 28, 2019 or September 29, 2018.

Costs and estimated earnings in excess of billings are composed principally of revenue recognized on contracts on the percentage of completion method for which billings had not been presented to customers because the amounts were not billable under the contract terms at the balance sheet date. In accordance with the contract terms, the unbilled receivables at the balance sheet date are expected to be billed in following periods. Billings in excess of costs and estimated earnings represent billings in excess of revenue recognized. Contract assets and liabilities are netted on a contract-by-contract basis.

In June 2018, the FASB issued ASU No. 2018-07, Compensation-Stock Compensation (Topic 718): Improvements to Nonemployee Share-Based Payment Accounting, increasing the scope of Topic 718 to include share-based payment transactions for acquiring goods and services from nonemployees. The ASU is effective for fiscal years beginning after December 15, 2018 and interim periods within those fiscal years. The adoption of this new ASU did not have a material impact on our consolidated financial results.